6. Neoplastic Dermatology

Question 1

General clinical features of

benign

vs

malignant neoplasm

Answer 1

• well-demarcated, uniform color, unchanged
  for years, lack of concerning symptoms (bleeding,
  ulceration, and pain)

vs

• rapid growth or new onset lesion with concerning features, such as pigment variegation, ulceration, pain, and bleeding

Question 2

General histological features of

benign

vs

malignant neoplasm

Answer 2

• well-circumscribed,
• bland cytology
• lacks architectural disorder, necrosis, cytologic atypia, atypical mitotic figures

vs

• poorly circumscribed proliferation of cells with atypical cytology
• architectural disorder
• signs of hyperproliferative state
• atypical mitoses (do not resemble any normal phase of cell division)

Question 3

Well-demarcated, waxy/verrucous brown “stuck-on” papules on hair-bearing skin

Dx?

Answer 3

Seborrheic keratosis

Question 4

Features of SKs

Answer 4

• Very common, onset on 4th decade
• Familial disposition, AD inheritance with incomplete penetrance
• a/w sun exposure
• FGFR3 and PIK3CA activating mutations
• spares mucosal sites

Question 5

Widespread eruption of SKs on trunk

Answer 5

Leser-Trelat sign

a/w underlying adenocarcinoma ( GI)

Question 6

Histological features of SK

Answer 6

• acanthosis
• papillomatosis
• hyperkeratosis with pseudohorn cysts
• flat base (“string sign”)
• bland keratinocytes without atypia, or many mitotic figures

Question 7

Name the histological variants of SKs

Answer 7

• Acanthotic (MC type)
• Hyperkeratotic
• Reticulated
• Irritated
• Clonal
• Melanoacanthoma

Question 8

Well-defined nests of paler/monotonous cells
mimicking Bowen’s disease, melanoma, or hidroacanthoma simplex

Dx?

Answer 8

Clonal seborrheic keratosis

Question 9

MC histological type of SK?

Answer 9

Acanthotic

Question 10

Heavily pigmented variant of SK?

Answer 10

Melanoacanthoma

Heavy pigment mostly in dendritic melanocytes

Question 11

Cutaneous

vs

oral melanoacanthoma

Answer 11

heavily pigmented variant of SK

vs

benign reactive process unrelated to cutaneous melanoacanthoma

Question 12

Sudden onset, pigmented lesion on buccal mucosa

Dx?

Answer 12

Oral melanoacanthoma

Question 13

Seborrheic Keratosis Histologic Variants

Answer 13

Question 14

Dx?

Answer 14

Dermatosis papulosa nigra

Question 15

Key features of dermatosis papulosa nigra(DPN)

Answer 15

• MC in individuals of African descent with darkly pigmented skin
• Multiple hyperpigmented papules on the face
• Variant of SK
• Histologically similar to acanthotic type of SK (acanthosis, papillomatosis, hyperkeratosis)

Question 16

Optimal treatment for dermatosis papulosa nigra?

Answer 16

Snip excision with scissors, curettage, and light electrodesiccation

Cryotherapy can result in hypopigmentation, bcz melanocytes are more sensitive to freeze damage than are keratinocytes

Question 17

Dx?

Answer 17

Stucco keratosis

Keratosis Alba

Question 18

Features of stucco keratoses

Answer 18

• Gray-white papules
• Typically on lower extremities of older adults, especially the ankles, dorsal aspect of foot
• Stuck on appearance
• Minimal bleeding when scraped off
• No familial predilection

Question 19

Tx of stucco keratosis?

Answer 19

• Topical application of urea, lactic acid, or retinoids may reduce the hard scale

(but the actual lesions persist)

• Curettage, or local destruction with cryosurgery or electrodesiccation