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MSS > Skin Pathology (Pigmented and Infectious Lesions) > Flashcards

Skin Pathology (Pigmented and Infectious Lesions) Flashcards

1
Q

What is Seborrheic Keratosis?

A
  • benign proliferation of squamous cells
  • common in the elderly.
  • presents as raised, discolored plaques on the extremities or face; often has a coin-like, waxy, ‘stuck-on’ appearance.
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2
Q

What characterizes seborrheic keratosis on histology?

A
  • keratin PSEUDOCYSTS
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3
Q

** What is Leser-Trelat sign?

A
  • SUDDEN ONSET of multiple seborrheic keratoses and suggests underlying carcinoma of the GI tract
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4
Q

What is Acanthosis Nigricans?

A
  • epidermal hyperplasia with darkening of the skin (VELVET-LIKE skin).
  • often involves the axilla or groin.
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5
Q

With what is acathosis nigricans associated?

A
  • insulin resistance (T2DM) or malignancy (especially gastric carcinoma).
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6
Q

*** What is Basal Cell Carcinoma?

A
  • malignant proliferation of the basal cells of the epidermis.
  • MOST COMMON CUTANEOUS malignancy.
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7
Q

What are the risk factors for basal cell carcinoma?

A
  • UBV-induced DNA damage (prolonged exposure to sunlight, albinism, and xeroderma pigmentosum).
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8
Q

*** How does basal cell carcinoma present?

A
  • elevated nodule with a central, ulcerated crater surrounded by dilated (TELANGIECTATIC) vessels (PINK-PEARL-LIKE papule).
  • classic location is UPPER LIP
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9
Q

What will you see on histology with basal cell carcinoma?

A
  • nodules of basal cells with peripheral palisading (cells are lining up against some space).
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10
Q

How do you treat basal cell carcinoma?

A
  • excision

* metastasis is rare and has excellent prognosis :)

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11
Q

*** What is Squamous Cell Carcinoma?

A
  • malignant proliferation of squamous cells characterized by formation of KERATIN PEARLS.
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12
Q

What are the risk factors for squamous cell carcinoma?

A
  • same as basal cell carcinoma: UVB-induced DNA damage from prolonged exposure to sunlight, albinism, and xeroderma pigmentosum.
  • ALSO: immunosuppressive therapy, ARSENIC POISONING, and chronic inflammation (ex. scar from burn or draining sinus tract).
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13
Q

*** How does squamous cell carcinoma present?

A
  • ulcerated, nodular mass, usually on the face (classically involving the LOWER LIP).
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14
Q

How do you treat squamous cell carcinoma?

A
  • excision

* metastasis is uncommon and has an excellent prognosis :)

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15
Q

What is Actinic Keratosis?

A
  • a PRECURSOR lesion of squamous cell carcinoma and presents as a hyperkeratotic, scaly plaque, often on the face, back, or neck.
  • may look like a little horn.
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16
Q

What is Keratoacanthoma?

A
  • well-differentiated squamous cell carcinoma that develops RAPIDLY and REGRESSES spontaneously.
  • presents as a CUP-SHAPED TUMOR filled with keratin debris.
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17
Q

What are the melanocytes?

A
  • responsible for skin pigmentation using TYROSINE to make MELANIN in the MELANOSOMES, which are passed off to the keratinocytes, resulting in skin pigmentation.
  • present in basal layer of epidermis and derived from NEURAL CREST.
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18
Q

What is Vitiligo?

A
  • LOCALIZED LOSS of skin pigmentation due to AUTOIMMUNE destruction of melanocytes.
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19
Q

What is Albinism?

A
  • CONGENITAL lack of pigmentation due to enzyme defect (TYROSINASE) that impairs melanin production.
  • may involve eyes (ocular form) or both eyes and skin (oculocutaneous form).
  • increased risk for skin cancer (basal cell, squamous cell, or melanoma) due to reduced protection against UVB.
20
Q

What is a Freckle?

A
  • small, tan to brown macule due to increased number of MELANOSOMES (melanocytes are NOT increased).
  • darkens when exposed to sunlight.
  • Lentigo is similar to a freckle, but does NOT darken when exposed to the sun.
21
Q

What is Melasma?

A
  • mask-like hyperpigmentation of the cheeks.

* associated with pregnancy and oral contraceptives.

22
Q

What is a Nevus (mole)?

A
  • benign neoplasm of melanocytes.

- CONGENTIAL nevus is present at birth; often larger and associated with HAIR= good sign :)

23
Q

What is an Acquired Nevus?

A

arises later in life:

  1. begins as nests of melanocytes at the dermal-epidermal junction (JUNCTIONAL nevus); most common mole in CHILDREN.
  2. grows by extension into the dermis (compound nevus).
  3. junctional component is eventually lost, resulting in an INTRADERMAL nevus, which is the most common mole in ADULTS.
24
Q

Can dysplasia arise in a nevus, leading to melanoma?

A

YES

25
Q

** What is Melanoma?

A
  • malignant neoplasm of melanocytes; MOST COMMON cause of DEATH from skin cancer.
26
Q

*** What are the risk factors for melanoma?

A

exposure to UVB:

  • prolonged exposure to sunlight
  • albinism
  • xeroderma pigmentosum
  • additionally DYSPLASTIC NEVUS SYNDROME= autosomal dominant disorder (CDKN2 and CDKN4) characterized by formation of dysplastic nevi (flat macules, slightly raised plaques with pebbly surface, or target like lesions with a darker raised center and irregular flat periphery).
27
Q

*** How do we distinguish melanoma from a nevus (mole)?

A
  • Asymmetry
  • Borders are irregular
  • Color is not uniform
  • Diameter greater than 6 mm
28
Q

What are the 2 growth phases of melanoma?

A
  1. RADIAL growth= horizontally along the epidermis and superficial dermis; LOW RISK of metastasis.
  2. VERTICAL growth= into the deep dermis; increased risk of metastasis.
29
Q

What is the most important prognostic factor in predicting melanoma metastasis?

A
  • DEPTH of extension (BRESLOW THICKNESS)
30
Q

What are the 4 major subtypes of melanoma?

A
  1. Superficial spreading= MOST COMMON and dominant early radial growth :)
  2. Lentigo maligna melanoma= radial growth :)
  3. Nodular= early vertical growth :(
  4. Acral lentiginous= arises on PALMS and SOLES, often in dark-skinned individuals; not related to UV light.
31
Q

What is Impetigo?

A
  • superficial bacterial skin infection (usually Staph aureus or Strep pyogenes) usually in CHILDREN.
  • presents as erythematous macules (flat lesion) that progresses to pustules, usually on the face.
  • rupture of pustules results in erosions and dry, crusted, honey-colored serum.
32
Q

What is Cellulitis?

A
  • DEEPER (dermal and subcutaneous) infection (usually Staph aureus or Strep pyogenes).
  • presents as a red, tender, swollen rash with FEVER.
33
Q

What are the risk factors for cellulitis?

A
  • recent surgery, trauma, or insect bite.
34
Q

To what can cellulitis progress?

A
  • NECROTIZING FASCIITIS= necrosis of SUBcutaneous tissue due to infection with anaerobic ‘flesh-eating’ bacteria, which produce CO2 leading to crepitus.
  • SURGICAL EMERGENCY.
35
Q

What is Staphylococcal Scalded Skin Syndrome?

A
  • sloughing of skin with erythematous rash and FEVER due to Staph aureus infection; exfoliative A and B TOXINS result in epidermolysis of teh stratum GRANULOSUM.
  • leads to significant skin loss
36
Q

*** How do you distinguish staphylococcal scalded skin syndrome from toxic epidermal necrolysis (TEN)?

A
  • by level of skin separation; TEN occurs at the dermal-epidermal junction.
37
Q

What is a Verruca (wart)?

A
  • flesh-colored papules (raised lesion) with a rough surface.
  • due to HPV infection of keratinocytes; characterized by koilocytic change.
  • HANDS and FEET are common locations.
38
Q

What is Mulluscum Contagiosum?

A
  • firm, pink umbiliciated papules due to POXVIRUS.

- most often arises in CHILDREN, but also can occur in SEXUALLY ACTIVE adults and immunocompromised individuals.

39
Q

What will you see on histology with mulluscum contagiosum?

A
  • keratinocytes with viral cytoplasmic inclusions (mulluscum bodies).
40
Q

What protective mechanism prevents progression to melanoma in malanocytic nevi?

A
  • accumulation of p16/INK4a, which inhibits cyclin-dependent kinases, arresting cell growth :)
  • this is disrupted however in melanoma :(
41
Q

What characterizes a Blue Nevus?

A
  • spindle shaped cells and heavy pigmentation.
42
Q

What is a Spitz Nevus?

A
  • usually occurs before puberty as a raised, pink or red nodule in the skin of the face.
  • SPINDLE (cigar shaped cells) or EPITHELIOID (polygonal shape with eosinophilic cytoplasm).
43
Q

What is a Halo Nevus?

A
  • melanocytic nevus surrounded by a zone of depigmented skin.
  • usually on trunk of young people.
  • heavy infiltration of lymphocytes.
44
Q

Does a malignant melanoma tend to have a better or worse prognosis if it is found on the back or chest?

A
  • WORSE than when found on the extremities.

* lymphocytic infiltrate indicates worse prognosis.

45
Q

What special stains can we use to identify malignant melanoma?

A
  • S-100

- HMB-45 (more specific)

46
Q

What is the most common primary intraocular malignancy in adults?

A
  • Ocular melanoma (spindle vs epithelioid types). Epithelioid has worse prognosis.
  • spreads hematogenously to liver.

MSS (9 decks)

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