Skin Flashcards
Vitiligo: Typically spared areas (2).
Scalp and eyelashes.
Urticarial vasculitis:
A. Clinical features (3).
B. Duration of urticaria.
A. Recurrent urticaria, arthralgia, abdominal pain.
B. More than 24 hours.
Urticarial vasculitis: Histology.
Leukocytoclastic vasculitis without significant fibrin in vascular walls.
Urticarial vasculitis: Useful adjunctive laboratory tests (2).
Complement studies (CH50, C1q-binding assays).
DFA: May show vascular deposits of complement, immunoglobulins, or fibrin.
Urticarial vasculitis: Clinical associations (3).
Infectious hepatitis.
Infectious mononucleosis.
Autoimmune diseases.
Telangiectasia macularis eruptiva perstans: Histologic differences from urticaria (2).
Mast cells rather than eosinophils.
No significant dermal edema.
Lichen planus: Microbiological association.
Hepatitis C.
Lichen planus: Anatomic predilection of lesions (3).
Flexor surfaces.
Lower back.
Glans penis.
Oral lichen planus: Histologic differences from lichen planus of skin (3).
Parakeratosis.
Less epidermal hyperplasia.
Frequent ulceration.
Lichenoid drug eruption: Histologic differences from lichen planus (2).
Parakeratosis.
Eosinophils (sometimes).
Lichen striatus:
A. Age group.
B. Clinical appearance.
A. Children.
B. Unilateral eruption on extremities, trunk, neck.
Lichen striatus: Histologic differences from lichen planus.
Inflammatory infiltrate deep in reticular dermis around hair follicles and sweat glands.
Lichen nitidus:
A. Age group.
B. Clinical appearance.
A. Children.
B. Small, flat-topped papules.
Lichen nitidus: Histologic differences from lichen planus (4).
“Ball-in-claw” infiltrate.
Focal parakeratosis.
Epidermal atrophy.
Many histiocytes.
Lichen planopilaris vs. alopecia areata: Histology (2).
Lichen planopilaris: Infiltrate at base of follicular bulb; scarring.
Alopecia areata: Infiltrate along infundibulum; usually no scarring.
Erythema multiforme:
A. Infectious cause.
B. Pharmacological cause.
A. HSV.
B. Sulfonamides.
Toxic epidermal necrolysis: Drugs that cause it (3).
Sulfonamides.
β-lactam antibiotics.
NSAIDs.
Erythema multiforme: Histological feature of late lesion.
Dermal melanophages.
Erythema multiforme: Immunofluorescence.
IgM and C3 in the walls of superficial dermal vessels.
Angioedema: Histology.
Extension of the edema into the subcutis.
Acute GVHD:
A. Timing.
B. Clinical triad.
A. Within 3 months after transplant.
B. Rash, diarrhea, liver dysfunction.
Acute GVHD: Grade I.
Vacuolar change in basement membrane.
Acute GVHD: Grade II.
Necrotic keratinocytes, satellite necrosis.
Acute GVHD: Grade III.
More widespread necrosis of keratinocytes; separation at dermoepidermal junction.
Acute GVHD: Grade IV.
Full-thickness necrosis and loss of epidermis.
Chronic GVHD: Early phase.
Lichenoid, resembling lichen planus; satellite necrosis may be seen.
Chronic GVHD: Late phase.
Sclerosis, resembling scleroderma, but with epidermal atrophy.
Discoid lupus: Histology (4).
Hyperkeratosis with follicular plugging.
Epidermal atrophy.
Basal vacuolar change.
Thickened basement membrane.
Verrucous lesions of lupus: Histology (2).
Epidermal hyperplasia, papillomatosis.
Tumid lupus: Histology.
Superficial and deep infiltrate that spares epidermis; increased dermal mucin.
Lupus panniculitis: Histology.
Lobular panniculitis with hyaline fat necrosis.
Subacute and neonatal lupus: Histologic differences from discoid lupus (3).
Subacute and neonatal lupus show
− Prominent changes at the D-E junction.
− Less hyperkeratosis.
− Less inflammation.
Cutaneous lupus: Immunofluorescence.
Continuous granular deposition of IgG, IgM, and C3 at the dermoepidermal junction.
Cutaneous lupus: How to distinguish from polymorphous light eruption.
PLE: More papillary dermal edema than tumid lupus; no dermal mucin.
Cutaneous lupus: Lymphoma that may be in the differential diagnosis.
Subcutaneous panniculitis-like T-cell lymphoma must be distinguished from lupus panniculitis.
Lupus band test.
Direct immunofluorescence . . .
Discoid lupus: Positive in lesional skin only.
Systemic lupus: Positive in “normal” skin as well.
Anatomic location:
A. Heliotrope rash.
B. Gottron’s papules.
A. Eyelids.
B. Knuckles, knees, elbows.
Dermatomyositis may resemble which type of cutaneous lupus histologically?
Subacute lupus.
Dermatomyositis: Age group.
Children.
Adults aged 45-65.
Dermatomyositis: Immunofluorescence.
C5b-C9 around blood vessels.
Dermatomyositis: Lupus-band test.
Negative.
Id reaction:
A. Synonym.
B. Leading cause.
A. Autoeczematization.
B. Remote dermatophytosis.
Spongiotic dermatitis: Changes that indicate chronicity (3).
Epidermal hyperplasia.
Hyperkeratosis.
Papillary dermal fibrosis.
Seborrheic dermatitis: Histology (2).
Mild spongiosis.
Parakeratosis at follicular ostia.
Pityriasis rosea: Histology (3).
Focal spongiosis.
Mounds of parakeratosis.
Extravasated erythrocytes.
Eosinophilic spongiosis: Differential diagnosis (4).
Allergic contact dermatitis.
Bullous pemphigoid, early.
Pemphigus, early.
Incontinentia pigmenti.
Incontinentia pigmenti:
A. Inheritance.
B. Epidemiology.
A. X-linked dominant.
B. Mostly females.
Histology of incontinentia pigmenti: Vesicular stage (3).
Eosinophilic spongiosis.
Single dyskeratotic keratinocytes.
Whorls of squamous cells.
Histology of incontinentia pigmenti: Verrucous stage (4).
Hyperkeratosis.
Papillomatosis.
Dyskeratosis.
Occasional eosinophils.
Incontinentia pigmenti: Gene and its location.
IKBKG (a.k.a. NEMO) on Xp28.
Histology of incontinentia pigmenti:
A. Hyperpigmented stage.
B. Hypopigmented stage (3).
A. Many melanophages in the upper dermis.
B. Epidermal atrophy, loss of melanin, loss of adnexa.
Psoriasis: Anatomic sites (3).
Scalp.
Lumbosacral skin.
Extensor surfaces.
Psoriasis: Eponymous collections of neutrophils.
Microabscesses of Munro (stratum corneum).
Spongiform pustules of Kogoj (stratum spinosum).
Psoriasis: Appearance of granular layer.
Hypogranulosis underlying areas of parakeratosis.
Guttate psoriasis: Histology.
Less epidermal hyperplasia than in classic psoriasis.
Psoriatic arthritis:
A. Incidence.
B. Affected joints.
A. 15% of patients with psoriasis.
B. The DIP joints.
Psoriasis: Risk factor for severe disease.
AIDS.
Pityriasis rubra pilaris: Clinical appearance of fully developed disease.
Orange-red scaly plaques containing islands of normal skin.
Pityriasis rubra pilaris:
A. Stratum corneum.
B. Follicles.
A. Horizontal and vertical alternation of orthokeratosis and parakeratosis.
B. Dilatation of infundibula; follicular plugging.
Pityriasis rubra pilaris: Histological differences from psoriasis (4).
Thick suprapapillary plates.
Short, thick rete pegs.
Hypergranulosis.
No neutrophils in the parakeratotic layer.
Polymorphous light eruption: Typical patient and season.
Young woman, summer.
Polymorphous light eruption: Anatomic distribution.
Upper chest, extensor surfaces of arms.
Polymorphous light eruption: Histology (3).
Normal or slightly spongiotic epidermis.
Marked papillary dermal edema.
Superficial and deep perivascular lymphocytes.
Pityriasis lichenoides: Histology (5).
Parakeratosis and scale-crust.
Spongiosis and necrotic keratinocytes.
Basal vacuolar change.
Papillary dermal edema with extravasated RBCs.
Lymphocytes obscure the DEJ and form superficial and deep perivascular infiltrates.
Pityriasis lichenoides et varioliformis acuta, ulceronecrotic variant: Histology.
There may be lymphocytic vasculitis.
Pityriasis lichenoides: Distinction from lymphomatoid papulosis.
The latter has atypical, CD30-positive lymphocytes.
Fixed drug eruption: Histology (4).
Basal vacuolar change that may progress into bullae.
Necrotic keratinocytes.
Superficial and deep perivascular lymphocytes, neutrophils, eosinophils; sometimes also lichenoid.
Melanophages in the upper dermis.
Fixed drug eruption: Distinction from erythema multiforme.
Not always possible, but fixed drug eruption is more likely when there is a deeper infiltrate that includes neutrophils and eosinophils.
Fixed drug eruption: Instigators (3).
Sulfa drugs.
Aspirin.
Phenolphthalein.
Lymphomatoid papulosis: Infiltrate.
Wedge-shaped and consists of neutrophils, eosinophils, plasma cells, and atypical lymphocytes.
Lymphomatoid papulosis: Morphology of atypical lymphocytes.
May resemble the cells of
Mycosis fungoides (cerebriform nuclei).
Hodgkin’s lymphoma (Reed-Sternberg cells)
Anaplastic large-cell lymphoma.
Lymphomatoid papulosis: Feared outcome.
Progression to anaplastic large-cell lymphoma.
Secondary syphilis: Histology (5).
Parakeratosis with neutrophils.
Psoriasiform epidermal hyperplasia.
Focal spongiosis.
Basal vacuolar change.
Lichenoid mononuclear inflammation.
Lues maligna: Histology.
Thrombotic endarteritis of deep dermal vessels, leading to ischemic necrosis and ulceration.
Sweet’s syndrome: Clinical triad.
Fever.
Rash.
Leukocytosis.
Sweet’s syndrome: Anatomic locations of rash.
Face.
Trunk.
Extremities.
Sweet’s syndrome: Association (3).
AML or other myeloproliferative neoplasm.
Inflammatory disease.
Solid tumor.
Sweet’s syndrome: Histology (3).
Dense infiltrate of neutrophils with nuclear dust but without leukocytoclastic vasculitis.
Papillary dermal edema.
Dilated blood vessels with plump endothelial cells and extravasated RBCs.
Pyoderma gangrenosum: Associations (4).
Connective-tissue disease.
Hematopoietic malignancy.
Inflammatory bowel disease.
Liver disease.
Pyoderma gangrenosum: Inflammation.
Center of lesion: Neutrophils.
Border: Mixed infiltrate.
Periphery: Mononuclear.
Pyoderma gangrenosum: Vasculitis.
Secondary vasculitis may arise in the necrotic, neutrophil-rich center.
Pyoderma gangrenosum in Crohn’s disease.
May contain granulomas.
Eosinophilic cellulitis: Clinical presentation.
Red patches evolve into painful plaques; recurrent.
Eosinophilic cellulitis: Association with peripheral eosinophilia.
Seen in at least half of cases.
Eosinophilic cellulitis: Histology (3).
Dense, diffuse dermal infiltrate of eosinophils, sometimes with
− Flame figures.
− Necrobiosis with palisades of histiocytes.
Eosinophilic cellulitis: Possible causes (5).
Insect bites.
Parasites.
Infections.
MPNs.
Drugs.
Scabies: Name of mite.
Sarcoptes scabei.
Scabies: Most common sites of burrows (3).
Webs between fingers.
Palms.
Male genitals.
Xanthogranuloma: How many are congenital?
About 20%.
Xanthogranuloma: Constituent cells.
Histiocytes.
Touton giant cells.
Neutrophils, eosinophils, lymphocytes.
Xanthogranuloma: Immunohistochemical distinction from Langerhans’ cell histiocytosis.
Langerhans’ cells express CD1a, S100, and langerin.
Reticulohistiocytosis: Clinical forms.
Localized: Limited to skin.
Systemic: Involves skin, heart, bone, joints, lymph nodes.
Systemic reticulohistiocytosis: Associations (3).
Hyperlipidemia.
Internal malignancies.
Autoimmune disease.
Reticulohistiocytoma: Morphology of defining cell.
Epithelioid histiocyte with abundant, pale-pink, glassy cytoplasm.
Granuloma annulare: Typical anatomic sites.
Dorsa of hands and feet, knees, ankles, elbows.
Granuloma annulare: Distribution of histiocytes.
Palisaded, interstitial, or a combination of both.
Granuloma annulare: Histological distinction from rheumatoid nodule.
Rheumatoid nodule:
- Necrobiosis is more eosinophilic and sometimes fibrinoid; no mucin.
- Subcutaneous location.
Granuloma annulare in children.
May be subcutaneous and hence difficult to distinguish from rheumatoid nodule.
Rheumatoid nodule: Anatomic sites (2).
PIP joints, MCP joints.
Necrobiosis lipoidica: Classic anatomic site.
Shins.
Necrobiosis lipoidica: Appearance of necrobiosis.
Basophilic degeneration of collagen.
Necrobiosis lipoidica: Relevance to diabetes (2).
Occurs in less than 1% of diabetics.
Occurs at a later age in diabetics than in non-diabetics.
Necrobiotic xanthogranuloma:
A. Clinical association.
B. Typical anatomic location.
A. Paraproteinemia.
B. Periorbital skin.
Necrobiotic xanthogranuloma: Histology (3).
Foam cells, Touton giant cells, lymphocytes.
Intervening zones of necrobiosis.
Lymphoid follicles sometimes.
Lupus pernio:
A. Site of lesions.
B. Clinical significance.
A. Central face.
B. Increased risk of pulmonary sarcoidosis.
Löfgren’s syndrome: Clinical triad.
Hilar adenopathy, acute polyarthritis, erythema nodosum.
A variant presentation of sarcoidosis.
Sarcoidosis: Appearance of granulomas.
Noncaseating; minimal peripheral lymphocytic infiltrate.
Sarcoidosis: Appearance of panniculitis.
Lobular pattern; noncaseating granulomas.
Foreign substances that can cause sarcoidal granulomas (3).
Silica.
Beryllium.
Zirconium.
Inflammatory infiltrate of leprosy:
A. Tuberculoid.
B. Lepromatous.
C. Borderline.
A. Granulomas.
B. Foam cells; few lymphocytes.
C. Foam cells and epithelioid histiocytes in poorly formed granulomas; many lymphocytes.
Leprosy: Where to find organisms.
Abundant in lepromatous leprosy; few in tuberculoid leprosy.
Found in histiocytes, nerves, arrectores pilorum.
Histoid leprosy.
Histologically resembles a histiocytoma but is full of acid-fast bacilli.
Lupus vulgaris: Etiologies (2).
Hematogenous spread to skin from reactivated pulmonary focus of TB.
Lymphatic spread to skin from cervical lymph nodes.
Lupus vulgaris:
A. Anatomic site.
B. Clinical course.
A. Central face.
B. Peripheral extension with atrophy and occasional ulceration.
Lupus vulgaris: Histology (3).
Tuberculoid granulomas with little or no caseation.
In older lesions, fibrosis replaces granulomas.
Epidermis may be atrophic, ulcerated, or hyperplastic.
Lupus vulgaris: Demonstration of bacilli.
Special stains rarely help.
PCR is better.
Lupus vulgaris: Complication.
Development of SCC or BCC.
Deep mycoses: Typical histology.
Pseudoepitheliomatous hyperplasia with extensive dermal suppurative and granulomatous inflammation.
Deep mycoses: Appearance of panniculitis.
Lobular; suppurative and granulomatous.
Blastomycosis: Histology of spores (3).
8-15 μm, thick-walled, broad-based budding.
Paracoccidiomycosis: Histology of spores (2).
6-20 μm, narrow-based budding.
Chromoblastomycosis: Histology of spores (3).
6-12 μm, thick-walled, dark-brown and in clusters (“copper pennies”).
Cryptococcus: Histology of spores.
2-4 μm (4-12 μm with capsule), narrow-based budding.
Histoplasmosis: Histology of spores.
2-4 μm, clear halo.
Sporotrichosis: Histology of spores.
4-6 μm, round or oval.
Pseudoepitheliomatous hyperplasia with suppurative and granulomatous inflammation: Differential diagnosis (3).
Deep mycoses.
Atypical mycobacterial infections.
Halogenodermas.
Cryptococcus: Alternative histology.
Xanthomatous infiltrate, especially in the immunocompromised.
Tuberculoid leprosy: Appearance of granulomas.
Elongated, surrounded by lymphocytes, arranged along neurovascular bundles.
Cutaneous leishmaniasis: Causes (3).
Old World: L. tropica.
New World: L. brasiliensis, L. mexicana.
Cutaneous leishmaniasis: Detection of parasites in a biopsy (2).
More likely to be seen in early lesions.
Giemsa stain can help.
Cutaneous leishmaniasis: Histology of late lesion.
Tuberculoid granulomas and lymphocytes.
Parasites may be undetectable.
Rhinoscleroma: Classic cell.
Mikulicz cell: Large histiocyte.
Granuloma inguinale:
A. Cause.
B. Inflammatory infiltrate.
C. Classic histologic finding.
A. Calymmatobacterium granulomatis.
B. Histiocytes and neutrophils.
C. Donovan body: Encapsulated, round to oval, 2-3 μm.
Leukocytoclastic vasculitis: Typically affected vessel in the skin.
Superficial dermal postcapillary venule.
Leukocytoclastic vasculitis: Bacterial cause.
Neisseria meningitidis.
Leukocytoclastic vasculitis: Immunofluorescence (2).
Most cases: IgM, C3, and fibrinogen around dermal vessels.
Henoch-Schönlein purpura: IgA.
Leukocytoclastic vasculitis: Chronic forms (2).
Erythema elevatum diutinum.
Granuloma faciale.
Livedo vasculitis: Anatomic location.
Lower legs.
Livedo vasculitis: Histology.
Fibrinoid matter in vessel walls leads to occlusion and ulceration.
Usually little inflammation.
Septic vasculitis: Histology.
Thrombi accompany leukocytoclastic vasculitis.
There may be intraepidermal pustules.
Causes of noninflammatory vasculitis of small vessels with deposits of pink matter in and around vascular lumens (4).
Monoclonal cryoglobulinemia.
TTP.
Warfarin- or heparin-induced vasculitis.
Superficial migratory thrombophlebitis: Associations (3).
Malignancy.
Hypercoagulable states.
Behçet’s disease.
Superficial migratory thrombophlebitis: Typically affected vessel.
Small or medium-sized vein in deep dermis or subcutis of lower extremity.
Superficial migratory thrombophlebitis: Histology (3).
Occluding thrombus.
Neutrophils, lymphocytes, and histiocytes infiltrate muscle of vein.
Recanalization and resorption of thrombus occur with granulomatous reaction.
Superficial migratory thrombophlebitis: Histologic distinction from nodular vasculitis.
Nodular vasculitis affects arteries as well as veins.
Subcorneal pustular dermatosis: Clinical appearance.
Sterile pustules involving flexural surfaces and axillary and inguinal folds.
Groups of pustules may assume annular or serpiginous patterns.
Subcorneal pustular dermatosis: Histology (2).
Neutrophils beneath the stratum corneum and around superficial vessels.
Mild acantholysis may occur.
Subcorneal pustular dermatosis: Helpful ancillary tests.
Gram stain to exclude bullous impetigo.
Immunofluorescence to exclude autoimmune bullous diseases.
Subcorneal pustular dermatosis: Possible clinical association.
Monoclonal gammopathy, esp. IgA.
Pustular drug eruption / acute exanthematous pustular dermatosis: Histology (3).
Subcorneal or intraepidermal pustules.
Spongiosis.
Dermal eosinophils.
Pemphigus: Clinical appearance of bullae.
Large, flaccid, fragile; positive Nikolsky’s sign.
Pemphigus: Anatomic distribution.
Scalp, around eyes, sternum, mid-back, umbilicus, groin.
Oral lesions can occur.
Pemphigus vulgaris: Histology of early lesion.
Eosinophilic spongiosis.
Pemphigus vulgaris:
A. Location of split.
B. Contents of bulla.
C. Inflammatory infiltrate.
A. Suprabasal.
B. Acantholytic keratinocytes.
C. Superficial dermal, often with eosinophils.
Pemphigus vegetans.
Variant of pemphigus vulgaris in which lesions heal with verrucous vegetations.
IgA pemphigus:
A. Histology.
B. Antigen.
A. Resembles subcorneal pustular dermatosis.
B. Desmocollin.
Pemphigus vulgaris: Direct immunofluorescence.
Intercellular IgG.
Location of staining by direct immunofluorescence in
A. Pemphigus vulgaris.
B. Pemphigus vegetans.
C. Pemphigus foliaceus.
A,B. Deep epidermis.
C. Superficial epidermis.
Location of staining by direct immunofluorescence in pemphigus erythematosus.
Superficial epidermis, or along the DEJ as in SLE.
Paraneoplastic pemphigus: Characteristic histological feature.
Interface dermatitis.
Paraneoplastic pemphigus: Direct immunofluorescence (2).
Intercellular IgG.
Granular IgG or IgM at DEJ may also be seen.
Paraneoplastic pemphigus:
A. Antigen.
B. Substrate for indirect immunofluorescence.
A. Desmoplakin.
B. Rat bladder.
Antigens involved in
A. Pemphigus vulgaris.
B. Pemphigus erythematosus.
A. Desmoglein III.
B. Desmoglein I, desmoglein III.
Hailey-Hailey disease:
A. Inheritance.
B. Histologic features not found in pemphigus vulgaris.
A. Autosomal dominant.
B. Full-thickness acantholysis, sparing of follicular epithelium.
Grover’s disease: Histologic distinction from pemphigus vulgaris.
Grover’s disease:
Acantholysis is more focal.
A single specimen may show a combination of keratinocytic abnormalities.
Darier’s disease:
A. Inheritance.
B. Clinical appearance.
A. Autosomal dominant.
B. Hyperkeratotic papules in a follicular distribution.
Darier’s disease: Histologic features not found in pemphigus vulgaris.
Corps ronds, grains.
Both diseases show suprabasal acantholysis.
Staphylococcal scalded-skin syndrome: Location of split.
In the granular layer.
Bullous pemphigoid: Clinical appearance of bullae.
Large, tense; negative Nikolsky’s sign.
Bullous pemphigoid:
A. Location of split.
B. Contents of bulla.
A. Subepidermal.
B. Many eosinophils (except in the cell-poor variant).
Bullous pemphigoid: Histology of early lesion (2).
Eosinophilic spongiosis.
Superficial dermal eosinophils.
Bullous pemphigoid: Immunofluorescence (2).
DIF: C3 and IgG at the DEJ.
Salt-split skin: Antibodies on the ceiling of the bulla.
Bullous pemphigoid: Involved antigens.
BP1 and BP2 in the hemidesmosomes.
Pemphigoid gestationis: Distinction from bullous pemphigoid (2).
May show more neutrophils and necrosis of basal cells.
Clinical correlation often required.
Epidermolysis bullosa acquisita: Clinical presentation.
Acral blisters that heal with scarring.
Epidermolysis bullosa acquisita: Distinction from bullous pemphigoid.
Salt-split skin: Antibodies on the floor of the bulla.
Porphyria cutanea tarda: Histologic features (3).
Subepidermal bulla with minimal inflammation.
Festooning extension of dermal papillae into the cavity of the bulla.
PAS-positive perivascular deposits in the papillary dermis.
Cicatricial pemphigoid: Clinical presentation.
Bullae that involve mucous membranes and heal with scarring.
Dermatitis herpetiformis: Anatomic sites (5).
Elbows, knees, back, buttocks, scalp.
Dermatitis herpetiformis:
A. Location of split.
B. Contents of bullae.
A. Subepidermal.
B. Neutrophils, variable numbers of eosinophils.
Dermatitis herpetiformis: Histologic features in addition to bullae (2).
Neutrophils in tips of dermal papillae.
Superficial perivascular lymphocytes, neutrophils, eosinophils.
Dermatitis herpetiformis: Direct immunofluorescence.
Granular IgA in dermal papillae of normal skin and lesional skin.
Linear IgA dermatosis: Distinction from dermatitis herpetiformis.
Histology: May not be possible.
Direct immunofluorescence: Linear IgA at the DEJ.
Bullous systemic lupus erythematosus: Distinction from dermatitis herpetiformis.
Direct immunofluorescence: Granular IgG and C3 at the DEJ.
Eosinophilic pustular folliculitis:
A. Typical patients.
B. Histology.
A. Infants, immunocompromised.
B. Eosinophils in subcorneal pustules, in perifollicular infiltrates, and in spongiotic foci.
Majocchi’s granuloma: Leading cause.
Trichophyton rubrum.
Follicular-occlusion triad.
Hidradenitis suppurativa.
Acne conglobata.
Perifolliculitis capitis abscedens et suffodiens.
Morphea / scleroderma: Early histology (2).
Perivascular and interstitial lymphocytes and plasma cells.
Thickening of bundles of collagen in the reticular dermis.
Morphea / scleroderma: Later histology (4).
Closely packed bundles of collagen.
Minimal inflammation.
Superficial displacement of eccrine glands.
Loss of other adnexa and of capillaries.
Morphea / scleroderma: Autoantibodies (2).
Morphea / CREST syndrome: Anticentromere.
Systemic sclerosis: Anti-Scl-70 (anti-topoisomerase).
Scleredema: Histology (2).
Collagen bundles are thickened but not hyalinized.
Hyaluronic acid fills widened spaces between collagen bundles.
Lichen sclerosus: Histology (4).
Epidermal atrophy.
Follicular plugging.
Basal vacuolar change.
Edema and homogenization of papillary dermis.
Radiation dermatitis: Vascular changes (2).
Superficial dermal telangiectasia.
Deep dermal blood vessels with fibrous thickening.
Nephrogenic systemic fibrosis:
A. Association.
B. Anatomic sites.
A. Renal disease.
B. Trunk and extremities.
Nephrogenic systemic fibrosis: Histology.
Thickened collagen bundles and CD34-positive spindled fibroblasts extending into subcutis and fascia.
Eosinophilic fasciitis: Histology.
Sclerosis and eosinophilic infiltrate of deep fascia.
Erythema nodosum: Anatomic location (2).
A. Acute: Extensor surfaces of legs; symmetrical.
B. Chronic: Legs; unilateral; recurrence at other sites.
Erythema nodosum: Associations (3).
Streptococcal pharyngitis.
Crohn’s disease.
Sarcoidosis.
Erythema nodosum: Typical histology.
Granulomatous septal panniculitis that begins with lymphocytic and granulocytic inflammation.
Erythema nodosum: Ancillary test.
Special stains to exclude infectious (esp. tuberculous) panniculitis.
Subcutaneous fat necrosis of the newborn: Possible complications (2).
Hypercalcemia.
Thrombocytopenia.
Subcutaneous fat necrosis of the newborn: Histology.
Predominantly lobular inflammation.
Fat necrosis surrounded by macrophages and giant cells that contain a radial (or stellate) arrangement of needle-shaped lipid crystals.
Sclerema neonatorum: Distinction from subcutaneous fat necrosis of the newborn (2).
Sclerema neonatorum
Affects premature rather than full-term newborns.
Exhibits little or no inflammation.
Post-steroid panniculitis: Histology.
May resemble subcutaneous fat necrosis of the newborn; clinical history is essential.
Pancreatic fat necrosis: Distinguishing histologic features (2).
Ghostlike fat cells with thick borders.
No radially arranged lipid crystals.
Lipodystrophy: Histologic distinction from subcutaneous fat necrosis of the newborn.
Absence of needle-shaped crystals.
Erythema induratum: Histology.
Mixed lobular and septal panniculitis with vasculitis and zones of fat necrosis.
Epidermal-inclusion cyst:
A. Synonym.
B. Inherited cause of multiplicity.
A. Infundibular cyst.
B. Gardner’s syndrome.
Steatocystoma multiplex: Inheritance.
Autosomal dominant.
Seborrheic keratosis: Name of keratin-filled cysts.
Horn cysts (pseudo−horn cysts if they communicate with the stratum corneum).
Squamous eddies vs. keratin pearls.
Squamous eddies: Whorls of keratinocytes without central parakeratosis; seen in irritated seborrheic keratoses.
Keratin pearls: Central parakeratosis; seen in SCC.
Dermatosis papulosa nigra: Histology.
Same as that of seborrheic keratosis.
Clear-cell acanthoma:
A. Age group.
B. Anatomic site.
C. Clinical appearance.
A. Middle-aged and older.
B. Lower extremities.
C. Ulceration; oozing surface.
Clear-cell acanthoma: Histology (3).
Abrupt change to pale keratinocytes.
Elongated rete ridges with well-vascularized dermal papillae.
Neutrophils among keratinocytes and in the overlying parakeratosis.
Clear-cell acanthoma: Cause of clearing of cells.
Glycogen.
Verruca plana: Anatomic sites (2).
Face.
Dorsa of hands.
Verruca plana: Histology (3).
Blunt epidermal papillae.
Parakeratosis but minimal hyperkeratosis.
Keratinocytes with viral changes.
Actinic keratosis vs. SCC in situ.
AK: Alternating parakeratosis and orthokeratosis; orthokeratosis at the follicular ostia.
SCC: Confluent parakeratosis.
Bowenoid papulosis vs. SCC in situ.
Indistinguishable by histology.
Bowenoid papulosis occurs as papules on genitals.
Keratoacanthoma: Inflammatory feature.
Microabscesses.
Verrucous carcinoma: Histology.
Tunnels of parakeratosis extending deep into the neoplasm.
Bulbous expansion of rete pegs (“elephant’s feet”).
Marjolin’s ulcer.
SCC arising on the edge of a longstanding ulcer or scar.
Trichoepithelioma: Inheritance of multiplicity.
Autosomal dominant.
Trichoepithelioma vs. BCC: Immunohistochemistry.
Trichoepithelioma: CD10 in stromal cells only.
BCC: CD10 in epithelial and stromal cells.
Giant solitary trichoepithelioma.
Several centimeters in size; found in deep dermis and subcutis.
Pilomatricoma:
A. Age group.
B. Anatomic sites (3).
A. Children, adolescents.
B. Face, neck, upper extremities.
Pilomatricoma: Clinical association of multiplicity.
Myotonic dystrophy.
Pilomatricoma: Significance of shadow cells.
They are matrical cells that are failing to form hair shafts.
Trichilemmoma:
A. Silhouette.
B. Histology of desmoplastic type.
A. Verruciform.
B. Irregular extensions of clear cells into sclerotic dermis simulate invasive carcinoma.
Cowden’s disease:
A. Inheritance.
B. Affected organs.
A. Autosomal dominant.
B. Malignancies may occur in breast, gastrointestinal tract, thyroid gland, reproductive organs.
Syndrome of multiple basal-cell carcinomas:
A. Name.
B. Other abnormalities (2).
A. Basal-cell-nevus syndrome.
B. Palmar keratotic pits, jaw cysts.
Syringoma: Clinical appearance.
Multiple yellow, firm papules, 1-3 mm.
Syringoma: Histology (3).
Cords and nests of monomorphous epithelial cells.
Comma-shaped ducts lined by two layers of cells and filled with proteinaceous matter.
Densely fibrotic stroma.
Syringoma: Special stain.
PAS
− May highlight contents of ducts.
− May stain cells of clear-cell syringoma (glycogen).
Syringoma vs. trichoepithelioma.
Trichoepithelioma contains keratin-filled infundibulocystic structures rather than ducts.
Syringoma vs. microcystic adnexal carcinoma.
MAC is solitary, larger, and extends deep into the dermis.
Poroma: Cell types.
Poroid cells: Dark.
Cuticular: Pale and forming tubules.
Poroma: Stroma.
Richly vascular.
Painful tumors of the skin.
Blue-rubber-bleb nevus. Eccrine spiradenoma. Neuroma, neurilemmoma. Glomus tumor. Angiolipoma. Leiomyoma.
Spiradenoma:
A. Anatomic site.
B. Number.
A. Trunk and extremities.
B. Usually single but can be multiple.
Spiradenoma: Cell types (3).
Small, dark cells in the periphery of nodules.
Large, pale cells occupy the centers and line the tubules.
Lymphocytes.
Spiradenoma: Extracellular elements (2).
Hyaline basement-membrane-like matter.
Rich vascular supply.
Spiradenoma: Why painful?
Contains many unmyelinated axons.
Cylindroma: Type of differentiation.
Apocrine.
Cylindroma: Cell types.
Small, dark cells in the peripheral of nodules.
Large, pale cells occupy the centers and line the tubules.
Multiplicity of cylindromas:
A. Inheritance.
B. Gene and its location.
A. Autosomal dominant.
B. CYLD on 16q12.1.
Multiplicity of cylindromas may occur with multiplicity of what other tumor?
Trichoepithelioma.
Clear-cell hidradenoma:
A. Synonyms (3).
B. Basic architecture.
A. Nodular hidradenoma, solid-cystic hidradenoma, eccrine acrospiroma.
B. Nodule consisting of cellular lobules and cystic spaces.
Clear-cell hidradenoma: Cell types (2).
Clear cells make up the bulk of the tumor.
Cuboidal or columnar cells with decapitation secretion line the tubules.
Syringocystadenoma papilliferum:
A. Anatomic sites.
B. Associated proliferation.
A. Scalp, face.
B. Naevus sebaceus.
Syringocystadenoma papilliferum: Cells that line the papillae.
Luminal row: Columnar cells with occasional decapitation secretion.
Deeper row: Cuboidal cells.
Syringocystadenoma papilliferum: Stroma.
Full of plasma cells.
Syringocystadenoma papilliferum vs. hidradenoma papilliferum (2).
Hidradenoma papilliferum:
− No connection to the skin’s surface.
− Papillae have one layer of cells (apocrine).
Syringocystadenoma papilliferum vs. tubular apocrine adenoma.
Tubular apocrine adenoma: No connection to skin’s surface.
Microcystic adnexal carcinoma: Anatomic sites (4).
Upper lip (#1).
Chin, nasolabial fold, cheek.
Microcystic adnexal carcinoma: Histology.
Bland-appearing ductal structures, with or without keratin-filled cysts, infiltrate deep dermis, subcutis, and muscle, getting smaller toward the base.
Usually no connection to the surface.
Microcystic adnexal carcinoma: Clue to malignancy.
Perineural invasion.
Microcystic adnexal carcinoma: Behavior.
Locally aggressive but rarely metastasizes.
Naevus sebaceus: Age group.
Present at birth.
Naevus sebaceus:
A. Clinical development.
B. Histologic development.
A. Plaque-like in infancy, linear in childhood, verrucous and nodular at puberty.
B. Sebaceous glands are large at birth and in puberty, small in childhood.
Naevus sebaceus: Non-sebaceous histology (3).
Papillomatosis.
Follicular germs resembling BCC.
Apocrine glands deep in the dermis.
Naevus sebaceus: Tumors that can arise in it (3).
Benign: Trichoblastoma, syringocystadenoma papilliferum.
Malignant: BCC.
Naevus sebaceus vs. epidermal nevus.
Epidermal nevus lacks sebaceous lobules.
Sebaceous adenoma: Histology.
Increased basaloid cells at periphery of sebaceous lobules.
Mitotic figures may be present, but no nuclear atypia.
Sebaceous adenoma, rippled-pattern: Histology.
Parallel rows of monomorphous, fusiform cells that resemble Verocay bodies.
Sebaceous cells and ducts also present.
Sebaceous adenoma: Ancillary study.
IHC for loss of mismatch-repair proteins (MSH2/MLH1) should be considered.
Sebaceous carcinoma: Anatomic site.
Eyelid, particularly the meibomian glands and the gland of Zeis.
Sebaceous carcinoma: Histology (2).
Irregular lobules consisting of pleomorphic basaloid cells, sometimes with a few sebaceous cells in the center.
Eyelid: Pagetoid spread into conjunctiva or epidermis.
Sebaceous carcinoma: Relationship to SCC (2).
Sebaceous carcinoma can
− Arise in a site of SCC.
− Contain SCC-like squamoid areas.
Sebaceous carcinoma: Hormonal receptor.
Androgen receptor (demonstrable by IHC).
Sebaceous carcinoma: Predictors of poor prognosis (5).
Size greater than 1 cm.
Poor differentiation.
Multicentricity.
Extensive invasion of tissues.
Lymphovascular invasion.
Sebaceous carcinoma: Behavior in the Muir-Torre syndrome.
Much less likely to metastasize.
Giant congenital nevus: Benign associations (2).
Leptomeningeal melanocytosis.
Neurological disorders.
Giant congenital nevus: Malignant associations (2).
Melanoma, rhabdomyosarcoma.
Giant congenital nevus: Typical histologic feature.
Infiltration of nevus cells into septa of subcutaneous fat.
Congenital melanocytic nevus: Histology (2).
Nevus cells congregate around adnexa and blood vessels and infiltrate between collagen bundles.
Congenital melanocytic nevus: Histologic pitfall.
Presence of occasional mitotic figures in dermal nodules does not make it a melanoma.
Spitz nevus: Mitotic figures.
May be present but are usually not atypical and do not occur at the base of the lesion.
Spitz nevus: Non-melanocytic histology (3).
Epidermal hyperplasia with hyperkeratosis and orthokeratosis.
Papillary dermal vascular ectasia.
Patchy perivascular lymphocytes and histiocytes.
Halo nevus:
A. Age group.
B. Anatomic site.
A. Children and young adults.
B. Back.
Halo nevus: Histology of melanocytes.
Early: Large and atypical.
Late: Absent.
Special sites of melanocytic nevi (6).
Scalp.
Acral skin.
Periauricular skin.
Periumbilical skin.
Breasts.
Genitals.
Lentigo maligna: Clinical definition.
Melanoma in situ on sun-exposed skin.
Superficial spreading melanoma.
Melanoma with extensive pagetoid spread.
Clark’s levels.
I: Melanoma in situ.
II: Extension into papillary dermis.
III: Filling of papillary dermis.
IV: Extension into reticular dermis.
V: Extension into subcutis.
Genes implicated in the pathogenesis of melanoma (6).
CMM1.
p16.
CDK4.
BRAF.
NRAS.
MEK (a kinase of MAP kinase).
Desmoplastic melanoma: Immunohistochemistry.
Positive: S100.
Negative: Mart-1, HMB45.
Angiokeratoma: Non-vascular histology.
Epidermal hyperplasia with hyperkeratosis.
Cavernous hemangioma: Syndromes (3).
Maffucci’s: CH + multiple enchondromas.
Kasabach-Merritt: CH with thrombosis leading to consumptive coagulopathy.
Blue-rubber-bleb: CH + vascular proliferations in the gastrointestinal tract.
Pyogenic granuloma vs. bacillary angiomatosis.
Bacillary angiomatosis contains clumps of granular basophilic material in which bacilli can be identified with Warthin-Starry or Giemsa stain.
Kaposi’s sarcoma: Epidemiological types (4).
Classic: Elderly men in S. and E. Europe.
Endemic: Young natives of Central Africa.
Epidemic: HIV patients.
Iatrogenic: Immunosuppressed patients.
Epidemic Kaposi’s sarcoma: Anatomic sites.
Trunk, mucous membranes.
Kaposi’s sarcoma, patch stage: Histology (3).
Slit-like spaces between collagen bundles.
Promontory sign.
Extravasated red blood cells.
Kaposi’s sarcoma, plaque stage: Histology (3).
Short fascicles of spindle cells.
Diffuse proliferation of irregular vascular spaces.
Intracytoplasmic hyaline globules.
Kaposi’s sarcoma, nodular stage: Histology (4).
Spindle cells and vascular spaces form nodules.
Nuclear atypia and mitotic figures.
Extravasated red cells and hemosiderin-laden macrophages.
Conspicuous hyaline globules.
Kaposi’s sarcoma, late aggressive stage: Histology.
Resembles aggressive sarcoma.
Kaposi’s sarcoma: Special staining of hyaline globules.
PAS positive, diastase resistant.
Epithelioid angiosarcoma: Morphology of neoplastic cells.
Large and pleomorphic; abundant eosinophilic cytoplasm; large nucleus with large nucleolus.
Epithelioid angiosarcoma: Histologic architecture (2).
Asymmetrical proliferation.
May lack distinct vascular spaces and thus resemble carcinoma or melanoma.
Epithelioid angiosarcoma vs. epithelioid hemangioma.
Epithelioid hemangioma:
− Symmetrical.
− No nuclear atypia.
Angiosarcoma: Immunohistochemistry (4).
CD31, CD34, ERG.
Lymphatic tumors: D2-40.
Angiosarcoma: Electron microscopy.
Weibel-Palade bodies (rod-shaped; resemble lysosomes).
Dabska tumor.
Malignant intravascular papillary angioendothelioma.
Angioleiomyoma: Anatomic site.
Extremities, esp. lower extremities.
Dartoic leiomyoma:
A. Anatomic sites.
B. Clinical presentation.
A. Scrotum, labium majus, areola.
B. Painless (unlike other leiomyomas).
Cutaneous leiomyosarcoma:
A. Age group.
B. Anatomic sites.
A. Second and third decades.
B. No anatomic predilection.
Cutaneous leiomyosarcoma:
A. Histologic architecture.
B. Metastasis.
A. Asymmetrical; forms fascicles; intermixed zones of hypercellularity and of better differentiation.
B. Hematogenous.
Keloid: Change in histology with age.
Early lesions: More vascular.
Older lesions: More fibrous.
Keloid vs. hypertrophic scar.
Hypertrophic scar:
− Limited to area of injury.
− Less myxoid matrix.
Dermatofibrosoma: Clinical sign.
Fitzpatrick’s sign: Pinching the lesion results in a dimple.
Dermatofibroma: Aneurysmal variant.
Vascular proliferation and hemosiderin.
Dermatofibroma: Cellular type.
Densely cellular; increased mitotic figures.
Dermatofibroma: Immunohistochemistry.
Positive: Factor XIIIa.
Negative: CD34 (except at periphery of cellular DF).
Dermatofibrosarcoma protuberans: Change in clinical appearance with age.
Early: Tan or brown nodule, slow-growing.
Later: Blue-red, multilobular nodule, rapidly growing.
Dermatofibrosarcoma protuberans:
A. Overlying epidermis.
B. Invasion of fat.
C. Cytological atypia and mitosis.
A. Atrophic.
B. Replacement or lacelike infiltration.
C. Present but not prominent.
Dermatofibrosarcoma protuberans: Translocation.
t(17;22) :: COL1A1−PDGFB.
Dermatofibrosarcoma protuberans: Variant.
Bednar tumor contains pigmented spindle cells.
Neurofibroma: Preferred anatomic sites (2).
Palms, soles.
Neurofibroma: Cellular components.
Schwann cells.
Fibroblasts.
(Mast cells in the background.)
Schwannoma: Zones of Antoni.
Antoni A: Hypercellular.
Antoni B: Hypocellular; mucinous background.
Dermatofibroma vs. neurofibroma: Overlying epidermis.
DF: Hyperplastic, with pigmented basal cells.
NF: Atrophic, with indistinct rete ridges.
Merkel-cell carcinoma: Anatomic sites.
Head.
Extremities.
Merkel-cell carcinoma: Associated epithelial malignancy.
Squamous-cell carcinoma.
Merkel-cell carcinoma: Cytokeratin stain.
Positive for CK20.
Merkel-cell carcinoma: Electron microscopy.
Membrane-bound dense granules; perinuclear bundles or whorls of intermediate filaments.
Merkel-cell carcinoma: Divergent differentiation (3).
Squamous.
Adnexal.
Melanocytic.
Urticaria pigmentosa: Four forms.
Arising in infancy or childhood without systemic lesions.
Arising in adolescence or adulthood without systemic lesions.
Systemic mast-cell disease.
Mast-cell leukemia.
Urticaria pigmentosa: Age group in which ___ lesions appear.
A. solitary
B. diffuse erythrodermic
C. telangiectasia macularis eruptiva perstans
A, B. Infants.
C. Adults.
Urticaria pigmentosa: Age group in which ___ lesions appear.
A. maculopapular
B. nodular and plaquelike
Both: Infants and adults.
Urticaria pigmentosa: Arrangement of mast cells in ___ lesions.
A. nodular and plaquelike
B. maculopapular and TMEP
C. erythrodermic
A. Throughout the dermis.
B. Around upper dermal blood vessels.
C. In a dense band in the upper dermis.
Urticaria pigmentosa: Location of split in the bullous type.
Subepidermal.
Urticaria pigmentosa: Stains for mast cells (5).
Giemsa, toluidine blue, Leder’s.
CD117, tryptase.
Systemic mast-cell disease: Affected organs (6).
Bones.
Lymph nodes, spleen.
Liver.
Gastrointestinal tract.
Central nervous system.
Letterer-Siwe disease:
A. Age group.
B. Clinical presentation.
C. Locations of skin lesions.
A. 3 months to 3 years.
B. Constitutional symptoms, extraosseous lesions.
C. Scalp, face, mouth, neck, trunk.
Hand-Schüller-Christian disease:
A. Age group.
B. Clinical presentation.
C. Classic triad.
A. 2-6 years.
B. Otitis media plus all or part of the classic triad.
C. Defects in cranial bones, exophthalmos, diabetes insipidus.
Hand-Schüller-Christian disease: Locations of skin lesions (3).
Chest, axillae, groin.
Eosinophilic granuloma:
A. Age group.
B. Locations of internal lesions.
C. Locations of skin lesions.
A. 2-5 years.
B. Bones, lungs.
C. Scalp, face, mouth, groin.
Langerhans’-cell histiocytosis: Arrangement of Langerhans’ cells.
Throughout the dermis and often in the epidermis.
Langerhans’-cell histiocytosis:
A. Immunohistochemistry.
B. Electron microscopy.
A. Positive: S100, CD1a, langerin.
B. Birbeck granules within Langerhans’ cells.
Langerhans’-cell histiocytosis: Possible genetic defect.
Activating mutation of BRAF.
Congenital self-healing reticulohistiocytosis: Clinical course.
Appears at birth or shortly thereafter.
Involution begins at 2-3 months.
Gone within 1 year.
Mycosis fungoides, patch stage: Histology.
Lymphocytes form a patchy infiltrate in a papillary dermis with thickened collagen bundles.
Lymphocytes form small collections within a minimally spongiotic epidermis.
There may be psoriasiform hyperplasia.
Mycosis fungoides, plaque stage: Histology.
Similar to that of patch stage, but with denser and more bandlike infiltrate.
Mycosis fungoides, tumor stage: Histology.
Atypical lymphocytes form diffuse infiltrate.
There are more medium and large lymphoid cells.
Mycosis fungoides: Large-cell transformation.
More than 25% of tumor cells are large cells, or there are discrete nodules of large cells.
Mycosis fungoides: Immunophenotype (4).
Positive: CD3, CD4, CD5.
Negative: CD8 (except in younger patients).
CD7 is diminished or lost.
CD30 is positive in large-cell transformation.
Mycosis fungoides: Sézary’s syndrome.
Erythrodermic mycosis fungoides + circulating tumor cells.
Mycosis fungoides: Related skin lesion.
Follicular mucinosis.
Cutaneous anaplastic large-cell lymphoma: Epidermal change.
Ulceration.
Cutaneous anaplastic large-cell lymphoma vs. lymphomatoid papulosis.
LP: Mixed infiltrate; fewer atypical lymphocytes.
CD30-positive lymphomas of the skin (3).
Anaplastic large-cell lymphoma.
Mycosis fungoides, late stage.
Pleomorphic T-cell lymphoma.
Dermatophytosis: The “sandwich sign”.
Fungal hyphae between the parakeratotic layer and the overlying orthokeratosis.
