Histo Characteristic Patterns Flashcards
Follicular plugging
Pityriasis rubra pilaris (PRP), lichen planopilaris (LPP), lichen sclerosus, lupus erythematosus (LE), perforating folliculitis
Cornoid lamella
Porokeratosis
Compact parakeratosis with retained KHG
Axillary granular parakeratosis
‘Checkerboard’ and ‘shoulder’ parakeratosis
PRP
Mounds of parakeratosis
Psoriasis
Focal parakeratosis
Guttate psoriasis, pityriasis rosea, pityriasis lichenoides
Confluent parakeratosis
Psoriasis, Bowen’s disease, necrolytic migratory erythema (NEM) in glucagonoma syndrome
Columns of parakeratosis
Verruca vulgaris (VV), porokeratosis
Alternating parakeratosis
Actinic keratosis (AK)
Sandwich parakeratosis
Tinea
Confluent hyperkeratosis
Lichen planus (LP)
Massive orthokeratosis
Acquired digital fibrokeratoma
‘Church spire’ papillomatosis
Acrokeratosis verruciformis
Papillomatosis
Acanthosis nigricans, VV, seborrheic keratosis (SK), acrochordon
Neutrophils in crust
Candidiasis, psoriasis, impetigo, tinea, syphilis
Munro microabscess in cornified layer
Psoriasis (plate-like neutrophils in multilayered scale)
‘Claw’ (epidermis) clutching a ‘ball’ (dermis)
Lichen nitidus
Epidermal necrosis
Herpes simplex (HSV) infection, toxic epidermal necrolysis, erythema multiforme (EM), NEM, hydroa vacciniforme, graft-versus-host disease (GVHD), acute fixed drug reaction (FDE)
Atrophic epidermis
Porokeratosis, atrophic AK, radiation dermatitis, lichen sclerosus, LE, dermatomyositis, poikiloderma, necrobiosis lipoidica, GVHD
Upper pallor with normal- appearing lower epidermis
NEM, +/- acrodermatitis enteropathica
Windblown appearance
Bowen’s disease
Subcorneal/intragranular split with acantholytic cells (cling on)
Pemphigus foliaceous (sometimes can look like impetigo if neutrophils within blister cavity)
Eosinophilic spongiosis (hAPPIE)
Arthropod bite, pemphigoid, pemphigus, incontinentia pigmenti (IP), eruption (drug), contact dermatitis
Foam cells in epidermis
Balloon cell nevus
Dyskeratotic or necrotic keratinocytes
EM, pityriasis lichenoides et varioliformis acuta (PLEVA), paraneoplastic pemphigus, acrodermatitis enteropathica, acute FDE, IP, NEM, GVHD, radiation dermatitis
Vacuolated keratinocytes (‘empty shells’)
Tissue processing artifact, freezing artifact, epidermolytic hyperkeratosis
Elongated keratinocytes
Electrodessication artifact
Acantholytic cells
Darier’s disease, Hailey-Hailey disease, HSV infection, transient acantholytic dermatosis (Grover’s disease), pemphigus (acantholysis involves hair follicles), warty dyskeratoma, acantholytic SCC or AK
Koilocytes
HPV infection
Multinucleated keratinocytes
HSV (steel gray nuclei)
Epidermotropic lymphocytes
Cutaneous T-cell lymphoma (CTCL)
Pagetoid cells
Bowen’s disease, melanoma, recurrent nevus, Paget’s disease, CTCL, lymphomatoid papulomatosis (LyP), Langerhans cell histiocytosis (LCH)
Dilapidated brick wall
Hailey-Hailey disease
Pautrier microabscesses
CTCL
Tombstoning of basal cells
Pemphigus vulgaris
Clumped keratohyaline granules (KHG)
Epidermolytic hyperkeratosis, verruca (HPV infection)
Squamous eddies
Irritated seborrheic keratosis (SK), inverted follicular keratosis (IFK), SCC, trichoblastoma
Horn pseudocysts
SK, IFK, trichoepithelioma, microcystic adnexal carcinoma
Basilar hyperpigmentation
Dermatofibroma, SK, acanthosis nigricans
Flattened (tabled) rete ridges
Dermatofibroma
‘Saw-toothed’ rete ridges
LP
Vacuolar interface change
LE, LP, GVHD, dermatomyositis, acute FDE, lichen nitidus, erythema dyschromicum perstans (ashy dermatosis), lichenoid keratosis, lichen sclerosus, EM, PLEVA
Thick basement membrane
LE
Grenz zone
Lepromatous leprosy, granuloma faciale, lymphocytoma cutis (bottom heavy), leukemia cutis (top heavy)
Subtle amorphous pink deposits in papillary dermis
Macular amyloidosis
Band-like lymphocytic infiltrate
LP, EM, lichen sclerosus, benign lichenoid keratosis, lichen striatus, halo nevus
Upper dermal edema
Polymorphous light eruption (PMLE), Sweet’s syndrome, lichen sclerosus, langerhans cell histiocytosis
Melanin incontinence
Macular amyloidosis, LE, atrophic LP, ashy dermatosis, FDE, dermatomyositis, postinflammatory hyperpigmentation, +/- IP
Subepidermal split with prominent eosinophils
Bullous pemphigoid, pemphigoid gestationis, bullous drug eruption
Subepidermal split with prominent neutrophils
Dermatitis herpetiformis, bullous SLE, linear IgA bullous disease (LABD)
Neutrophils in dermal papillae
Dermatitis herpetiformis
Subepidermal split with prominent lymphocytes
Bullous LP, PMLE, lichen sclerosus
Subepidermal vesicles with scant inflammation
Porphyria cutanea tarda (PCT)
Subepidermal vesicles with mast cells
Bullous mastocytosis
Fibrous stroma
Syringoma, trichoepithelioma, morpheaform BCC, microcystic adnexal carcinoma
‘Bubble gum’ pink stroma
Neurofibroma
Lymphocytes around sweat glands
Lichen striatus
Sweat glands with neutrophils
Neutrophilic eccrine hidradenitis
Necrosis of sweat glands
Coma blister
Invaginated pilosebaceous unit with dark-staining ducts
Supernumerary nipple
Extravasated red blood cells
Pityriasis rosea, PLEVA, stasis dermatitis, pigmented purpuric dermatoses, vascular neoplasms, vasculitis, granuloma faciale (GF)
Hemosiderin
Hemochromatosis, pigmented purpuric dermatosis, stasis dermatitis, GF, pityriasis lichenoides, vascular neoplasms, vasculitis
Vertically-oriented collagen
Acquired digital fibrokeratoma
Collagen trapping at periphery
Dermatofibroma
Keloidal collagen
Dermatofibroma, keloid
Necrobiosis
Granuloma annulare (GA), necrobiosis lipoidica diabeticorum (NLD), rheumatoid nodule, necrobiotic xanthogranuloma (NXG)
Horizontal ‘sandwich’ necrobiosis without palisading
NLD
Dermal fibrosis
Angiofibroma, fibrous papule, hypertrophic scar, blue nevus, keloid, radiotherapy, morpheaform BCC, desmoplastic trichoepthelioma, syringoma
Dermal necrosis
Epithelioid sarcoma, malignant atrophic papulosis (Degos)
Clumped calcified elastic fibers
Pseudoxanthoma elasticum (PXE)
Vasculitis
GF, erythema elevatum diutinum (EED), polyarteritis nodosa (PAN), Henoch-Schonlein purpura, urticarial vasculitis, acute hemorrhagic edema of infancy
Nuclear dust
Sweet’s syndrome, leukocytoclastic vasculitis, GF, PAN, pyoderma gangrenosum (PG)
Deep pink nodules
Nodular amyloidosis
Smooth muscle bundles
Supernumerary nipple, leiomyoma (fascicles and bundles)
Calcification
Pilomatricoma, PXE, calciphylaxis, osteoma cutis, cysts, panniculitis, calcinosis cutis, subepidermal calcified nodule
Increased mucin deposition
LE, dermatomyositis, scleromyxedema, scleredema diabeticorum, BCC (some), mucopolysaccharidosis, reticular erythematous mucinosis, GA (not NLD), pretibial myxedema, focal mucinosis, follicular mucinosis
Pool of mucin
Myxoid cyst, mucocele, focal cutaneous mucinosis, mucinous carcinoma
Ductal cells floating in mucin
Eccrine mucinous carcinoma
Tadpole-shaped ducts
Syringoma
Extracellular pool of lipid
Eruptive xanthoma
Empty vacuoles in dermis and epidermis
Freeze artifact
Pink to purple reticular network in dermis
Gel foam artifact
Drag marks
Cutting artifact (knife mark artifact)
Tiny black particles around blood vessels
Argyria
Black amorphous deposits around blood vessels
Lead tattoo
Tiny wispy gold to black granules in mouth
Amalgam tattoo
Nerve bundles
Amputation neuroma, supernumerary digit
Stromal retraction
BCC
Basaloid islands (jigsaw puzzle)
Cylindroma
‘Cluster of grapes’ (low power)
Merkel cell carcinoma
Hyalinized droplets
Cylindroma
‘Cannon’ or ‘blue balls’ in dermis
Eccrine spiradenoma
Circular basaloid rosettes
Eccrine spiradenoma
Spindle and epithelioid melanocytes ‘raining’ down
Spitz nevus
Lichenoid infiltrate
LP, lichenoid drug eruption, lichen sclerosus, secondary syphilis (with plasma cells), GVHD, pityriasis lichenoides, lichen striatus, CTCL
Interstitial dermatitis
GA, Well’s syndrome, Sweet’s syndrome, interstitial drug reaction, urticaria
Coat-sleeving or perivascular cuffing of lymphocytes
Erythema annulare centrifugum (no epidermal change)
Superficial and deep lymphocytic infiltrate
PMLE, secondary syphilis, gyrate erythemas, athropod bites, LE (latter includes periadnexal infiltrate)
Deep infiltrate around sweat glands
Lichen striatus
‘Naked’ granulomas
Sarcoidosis, tuberculosis, tuberculoid leprosy
Single filing or ‘indian’ filing of cells
GA, congenital melanocytic nevus, lymphoma, leukemia, glomus cell tumor, metastatic breast carcinoma
Increased mast cells
Urticaria, neural tumors (i.e. neurofibroma), mucinous areas
Increased plasma cells
Mucous membrane (normal), secondary syphilis, syringocystadenoma papilliferum, hidradenitis suppurativa, acne keloidalis nuchae, NLD, LE, Rosai-Dorfman disease
Basaloid cells
BCC, SK, trichoepithelioma, eccrine tumors
Diffuse dermal mast cells
Mastocytosis (ie. urticaria pigmentosa)
Cells with reniform nuclei
Langerhans cell histiocytosis (abundant pale cytoplasm)
Spindle-shaped cells with elongated, wavy nuclei
Neurofibroma
Round monotonous cells
Glomus cell tumor, poroma, mastocytosis (blue-purple granules)
Pink granular cytoplasm
Granular cell tumor
Clear cells
Clear cell acanthoma, trichilemmoma, clear cell hidradenoma, metastatic renal cell carcinoma, clear cell SCC, balloon cell nevus, Paget’s disease, clear cell syringoma, eccrine carcinoma
Small cells
Lymphocytoma cutis, cutaneous B cell lymphoma, metastatic small cell carcinoma, CTCL, merkel cell carcinoma
Foamy macrophages
Xanthomas (eruptive, tuberous, tendinous, planar), verruciform xanthoma, xanthelasma, xanthoma disseminatum, AFX, juvenile xanthogranuloma (JXG), NXG, leprosy, pancreatic panniculitis
Touton giant cell
Xanthelasma, AFX, NXG
Ground glass giant cell
Multicentric reticulohistiocytosis, reticulohistiocytic granuloma
Purple osteoclast-like giant cell
Giant cell tumor of tendon sheath, malignant fibrous histiocytoma
Bizarre multinucleated giant cell
Malignant fibrous histiocytoma, pleomorphic lipoma
Parasitized histiocytes His GiRL
Histoplasmosis, granuloma inguinale, rhinoscleroma, leishmaniasis
Ghost cells
Pilomatricoma
Fibroblast with red inclusion body
Infantile digital fibromatosis
Bizarre spindle cells
Liposarcoma, leiomyosarcoma, AFX, radiation dermatitis
Melanin clumps (casts) in follicle
Trichotillomania
Trichomalacia (deformed shaft)
Trichotillomania
Necrosis of hair follicles
HSV
Tiny vellus hairs
Accessory tragus (rim periphery), xanthelasma, vellus hair cyst
‘Swarm of bees’ (lymphocytic inflammation at hair bulb)
Alopecia areata
Lymphocytes and plasma cells around follicles
Acne keloidalis nuchae
Free hair shafts surrounded by multinucleated giant cells
Acne keloidalis nuchae, folliculitis decalvans
Eosinophils around hair follicle
Eosinophilic folliculitis
Mucin within follicle
Follicular mucinosis
Cartilage often present
Accessory tragus, chondrodermatitis nodularis helicis (CNH), chondroid syringoma
Degenerated cartilage
Relapsing polychondritis, CNH
Ghost-like fat cells
Pancreatic panniculitis (with basophilic calcium deposition)
Cystic spaces in fat
Cold panniculitis
Fat necrosis
Erythema induratum (basophilic), lupus panniculitis (latter with lymphoid follicle-like aggregates, lymphoplasmacytic infiltrate)
“Needle-shaped” clefts in fat
Subcutaneous fat necrosis, sclerema neonatorum, post-steroid panniculitis
‘Swiss cheese’ appearance
Paraffinoma or sclerosing lipogranuloma
Fat high up in lesion
Accessory tragus
Widened septae with giant cells
Erythema nodosum
Dense neutrophilic inflammation
alpha-l-antitrypsin deficiency
Lipomembranous changes
Lipodermatosclerosis
Chicken wire pattern (linear collapsed vessels)
Myxoid liposarcoma
Clear multivacuolated cells in fat
Hibernoma
Hyalinized vessel walls (with thick red color around vessels)
Atrophie blanche
Promontory sign, slit-like spaces
Kaposi sarcoma
Atypical endothelial cells with dissecting vascular spaces
Angiosarcoma
Intravascular thrombi
Cryoglobulinemia, purpura fulminans, antiphospholipid syndrome, disseminated intravascular coagulation, coumadin necrosis, atrophie blanche
Telangiectatic vessels in pale acellular dermis
Radiation dermatitis
Hob nailing (endothelial cells protrude into vessel)
Angiolymphoid hyperplasia with eosinophilia
Staghorn appearance
Hemangiopericytoma
Recanalizing thrombus
Masson’s tumor (intravascular endothelial hyperplasia)
Spindle cells with RBCs ‘sandwiched’ in between
Kaposi sarcoma
Polypoid collection of vessels
Pyogenic granuloma
Proliferation of thick-walled vessels with hemosiderin
Stasis dermatitis
Dilated engorged vessels with surrounding edema
Granulation tissue