Derm Pathology Flashcards
What are the 5 layers of the epidermis (superficial –> deep)?
Corneum Lucindum (thick skin only) Graulosum Spinosum Basale
Define Acanthosis
Thickening of the epidermis, often due to thickening of stratum spinosum
What is desquamatization? How long does it take?
Maturation of keratinocytes from undiff basal cells to diff cornified cells
Takes about 25 days normally
Ichthyosis
What is seen grossly?
Fish-like scales
Ichthyosis
Cause
Defective desquamatization leads to a buildup of a compacted scale
Mostly hereditary that appear at birth
Ichthyosis Vulgaris
Histology
Hyperkeratosis
Fish-like scales
What is hyperkeratosis?
Thickening of the cornified layer
Seborrheic Keratosis
Gross appearance
Generally well circumscribed with a “stuck on” appearance
Mostly in ppl above age 30
Seborrheic Keratosis
What is it? Describe the histology
Benign epithelial neoplasm
Hyperkeratosis
Undulations = papillomatosis
Horn cysts- small cysts filled with keratin
String sign – flat bases
Acanthosis Nigricans
Gross appearance
Velvety appearance on neck or axilla
Acanthosis Nigricans
Histology
Lots of papillomatosis Increased pigmentation (increased melanin)
Acanthosis Nigricans
Benign or Malignant?
Benign type in childhood (may be related to obesity or endocrine disorder)
May be a sign of malignancy in adulthood
Seborrheic Keratosis
Lesar Trelat Sign
Paraneoplastic Syndrome
Many seborrheic keratoses coming up at once – may be a sign of malignancy
What is a Fibroepithelial Polyp?
Skin tag
Actinic Keratosis
Gross appearance and Cause
Scaly erythematous patch on sun-damaged skin
Actinic Keratosis
Histology
Atypia of the lower levels of epidermis
Solar elastosis in dermis – grey-blue color
Flag sign (alternating pink/blue)
Inflammation with lots of T lymphocytes
Actinic Keratosis
Precursor to…
SCC
SCC
What mutations are most common?
P53
Could also have mutations in HRAS or Notch
SCC
Risk of Metastasis
Low (Less than 5%)
SCC
Risk factors
Sun-exposed sites Older age M > F Immunosuppression (HPV 5 and 8) Industrial exposures Chronic wounds Arsenic Burn scars Ionizing radiation
SCC
Gross appearance
Hyperkeratotic
Ulcerated
Papules and nodules
SCC
Histology
Invasion of malignant cells into sun-damaged dermis
Keratin pearls
Atypia in squamous keratinocytes
SCC In Situ (Bowen’s Disease)
Describe the histology
Full thickness atypia of the epithelium (dark cells, mitotic figures, apoptosis)
Often see acanthosis
Basal layer is unaffected/uninvaded
SCC In Situ (Bowen’s Disease)
Gross Appearance and Treatment
Plaque-like lesion that needs to be cut out
Bowenoid Papulosis
Cause, Location, Appearance, Prognosis
HPV induced, often on genitals
Multiple papules
May spontaneously regress or progress
Basal Cell Carcinoma
Gross appearance
Pearly pink papule with overlying telangiectasia
Basal Cell Carcinoma
Histology
Blue tumor
Peripheral pallisading of nuclei
Islands of basaloid cells in the dermis (nodular type)
Basal Cell Carcinoma
Mutations in…
PTCH (regulates Hedgehog pathway signaling)
P53
Basal Cell Carcinoma
Two genetic diseases associated with this disease….
Xeroderma Pigmentosum (aut recessive, DNA mismatch repair syndrome)
Nevoid Basal Cell Caricnoma Syndrome = Gorlin Syndrome
(Aut dom, mutation in PTCH)
Melanocytes
Where are they located? What is their appearance and function?
Located on basal layer in epidermis
Dark and small nuclei
Release melanin and pass the pigment off to neighbors
Also have a small “cap” of pigment to protect themselves from DNA damage
What is a freckle?
Small, tan-red macules on sun exposed areas
Increased melanin pigment with basal keratinocytes
What is a Melanocytic Nevi?
Tan-brown macules and papules
May be common or dysplastic
Difference between Common and Dysplastic Melanocytic Nevi
Common: Junctional, compound and intradermal: nests of melanocytes
Dysplastic: single and cytologically atypical melanocytes; nests with architectural atypia
What are Dysplastic Nevi?
Architecturally atypical with melanocytic nests that may be alrger and fused
Single melanocytes along DEJ
Cytologic atypia
Dysplastic Nevi
Prognosis
Vast majority are clinically stable, but some consider it to be a risk factor for melanoma
Dysplastic Nevus Syndrome
What is it? What is the common mutation?
Tendency to develop many dysplastic nevi and melanomas
Mutation in CDKN2A and CDK4 mutations
Melanoma
What are the ABCDEs?
Asymmetry Borders (irregular) Color Diameter Elevation/Evolving
Melanoma
Prognostic Factors
Depth of tumor
Ulceration of tumor
of mitotic figures
What is the major mutation in sporadic melanomas?
BRAF mutations (60% of melanomas)
How are melanomas with BRAF mutations treated?
Vemurfenib (a monoclonal Ab against BRAF)
What are the two major predisposing factors to melanoma?
Sun exposure and family history
When do melanomas acquire metastatic potential?
When they develop a vertical growth phase, so it is important to cut them out before that
Describe the 4 Stages of Melanoma
0: Melanoma in situ
I/II: Confined to skin (any depth)
III: nodal involvement
IV: distant skin or viscera
Trichelemmoma
- Mutation
- Syndrome
- Risks
PTEN mutations
Cowden’s syndrome
Increased risk for breast, endometrial, thyroid cancer
What is a dermatofibroma and how is it identified?
Pink/brown papule or nodule most common on lower extremities
Dimpling sign
Dermatofibrosarcoma Protuberans
What is it? What does nit look like?
Large nodule with several protuberances
Dense proliferation of spindle cells within the dermis
Cylindroma
- Location
- Appearance on histology
Common on scalp (turban tumor)
basaloid islands in puzzle pieces
What is a sebaceous adenoma? How is it addressed?
Papule or small nodule that looks like BCC
Work them up for Lynch Syndrome (HNPCC) – look for MLH1, MSH2, MSH6 mutations
Leiomyoma
What is it?
Appearance on Histology?
Tumor of the smooth muscle of dermis
Histology: Bubbles and cigar shaped cells
Polyarteritis Nodosum/Erythema Induratum
What is it? What is the rash appearance?
Vasculitis of small and medium sized arteries
Purpura on skin, often with ulceration and on lower limbs
Erythema Nodosum
- Location
- Appearance
- Workup
Front of legs
Macular appearance
Work them up for TB
P’s of Lichen Planus
Purple Papules Plaques Pruritic Polygonal
Lichen Planus
Common location and appearance
Oral mucosa is common
Wickham striae – white lines across the lesion
Erythema multiforme
- Appearance
- Prognosis
- Cause
Annular lesion (often targetoid)
Often resolves spontaneously and is associated with viruses
TEN and SJS
Describe the histology
Civatte bodies (necrotic keratinocytes)
TEN = necrotic keratinocytes at all levels of epidermis
DLE
- Appearance on Histology
- Stains to use
Mostly cutaneous
Lichenoid infiltrate and interface change
Mucin
Get thickened basement membrane seen on PAS stain
LS&A (Lichen Sclerosis et Atrophicus)
Appearance (histology and gross)
Lichenoid infiltrate gets pushed down, leaving behind pink hyaline
Often appears as a thinning white patch on vulva
Psoriasis
Associated with…
HLA-C haplotype
Arthritis Myopathy Enteropathy Spondylitis joint Acquired immunodeficiency
Psoriasis
Gross Appearance
Well demarcated plaques with silver/white scales
May also have yellow/brown nail discoloration with pitting
“Peeling off sign” – peel off scale, see pinpoint hemorrhage due to elongated Rete pegs
Psoriasis
Histology
Elongated Rete pegs
Acanthosis is even
Wafer like scale of PMNs
Allergic Dermatitis
Histology
Spongiotic dermatitis with EOSINOPHILS
Bullous Pemphigoid
- Gross appearance
- Histology
- DIF
Tense bullae
Subepidermal blister with eosinophils
DFA reveals IgG antibodies to HEMIDESMOSOMES (lines up along the DEJ in a linear fashion)
Pemphigus Vulgaris
- Gross appearance
- Histology
- DIF
Loose flaccid blister
May rupture easily
Suprabasalar clefting = tombstoning
Net-like IgG and C3 on DIF (Antibodies formed against DESMOSOMES)
Dermatitis Herpetiformis
- Associated with…
- Treated with…
- DIF
Assoc with celiac disease and treated with a gluten free diet
Granular IgA deposits on direct immunofluorescense
Sarcoidosis
-Histology
Chronic granulomatous inflammation with few lymphocytes (naked granulomas)
Henoch Schonlein Purpura
What it is?
-DIF
Leukocytoclastic vasculitis with arhtritis, abd pain, or hematuria
IgA seen around vessel walls
Mycosis Fungoides
Gross appearance and Histology
Cutaneous T Cell Lymphoma
-Dark or erythematous patches and plaques, often on trunk
Histo: Lymphocytes with dark nuclei line up at the DEJ
Verruca Vulgaris
- Cause
- Histology
Wart caused by HPV
Hyperkeratosis and hypergranulosis seen above papillomatosis
See Koilocytes: vacuolated keratinocytes with raisin like nuclei
Molluscum Contagiosum
- Appearance
- Histology
Small papuls that often look umbilicated
Seen in kids
Histology: crater with epidermis reaching down; may see molluscum bodies
3 Ms of HSV infection
Molding (nuclei)
Multinucleation
Marginalization
Primary VZV infection is….
- Appearance
- Transmission
Chicken Pox
Vesicles on red base/papules/crusted erosions
Transmitted by resp secretions
Reactivation of latent VZV infection is…
Shingles
Painful vesicles in a dermatomal distirbution
HZV Infection
Hutchinson’s sign
Involvement of the nose
Should make you think of potential ocular involvement, which needs immediate attention
Impetigo
- Causes
- Appearance
- Histology
Staph aureus or Strep pyogenes
Loose blisters with honey colored crusts, often on face
Histo: Subcorneal blister filled with PMNs and debris
Tinia infections
- Where may they be located?
- Appearance
Pedis- foot
Corporis- body
Cruris- genitals
Capitus- head
Annular (ring-like) lesion
What is onchomycosis?
Fungi seen in the nail
How to identify Tinia infections
Do a biopsy (scrape) in the office and look at it under a KOH prep or PAS stain
Tinea versicolor
- Appearance
- Histology
Macules or patches of hypopigmentation/hyperpigmentation on the trunk
Hyphae and yeasts form in the CORNEUM (spaghetti and meatballs pattern)
Scabies
- What is it?
- Histology
Mite infection that is highly contagious
Forms a blister in the corneum
Blastomycosis
-Histology
Epidermal acanthosis
Broad based budding yeast
Can mimic SCC
Coccidiomycosis
Appearance
Mariner’s wheel = single larger form filled with tinier yeasts
Cryptococcus
Appearance
Encapsulated yeast seen with mucicarmine
Histoplasma
Appearance
Small intracytoplasmic organisms with surrounding clear halo
PAS and GAS +
