Elston Chapter 2: Benign tumors and cysts of the epidermis

Question 1

What is a benign acanthoma?

Answer 1

benign cutaneous neoplasm characterized by expansion of epidermis

may be composed of clones of cells that displace or compress preexisting epidermis

rete ridge pattern is commonly ablastic by neoplastic tissue of acanthoma

includes SKs, melanoacanthomas, clear cell acanthomas, large cell acanthoma, inverted follicular keratosis, warty dyskeratoma, epidermolytic acanthoma, epidermal nevi

Question 2

seborrheic keratoses

Answer 2

cells typically smaller than cellso f surrounding epidermis and commonly pigmented

architecture can include acanthotic, hyperkeratotic, reticulated and clonal

melanoacathoma is distinct subtype composed of small keratinocytes and dendritic melanocytes

SKs have characteristic loose lamellar shreded-wheat stratum corneum

excepsions include irritated inflamed which often have compact brightly eosinpohilic parakeratotic stratum corneum

melanoacanthomas produce deeply eosionphilic compact parakeratotic stratum corneum, even when not irritated or inflamed

can express BCL-2, marker associated with resistance to programmed cell death (apoptosis)

can also get activating point mutations in gene encoding fibroblast growth factor receptor 3, a tyrosine kinase receptor

Question 3

horn cysts vs pseudohorn cysts

Answer 3

horn cysts completely encased within acanthoma

pseudohorn cysts open to surface

Question 4

squamous eddies

Answer 4

whorl-like pattern of squamoid cells often found in SK and SCC

Question 5

Dowling-Degos disease/reticulated pigmented anomaly of the flexures

Answer 5

in ddx of reticulated SK

resembles multiple foci of reticulated SK hanging off of hair follicles with comedo-like dilated keratin-filled follicular infundibula

Question 6

Hidroacanthoma simplex

Answer 6

clonal islands of small keratinocytes similar in appearance to those of clonal seborrheic keratosis

ducts are present focally within the clonal islands

Eccrine poroma - either intraepidermal (“hidroacanthoma simplex”), intradermal (“dermal duct tumor”) or mixed (most common)

Question 7

Answer 7

dowling degos

Question 8

Answer 8

hidroacanthoma simplex/poroma if dermal component present too

Question 9

Melanoacanthoma

Answer 9

acanthoma composed of both small keratinocytes and pigmented dendritic melanocytes

most pigment is within dendrites

overlying statum corneum is almost always compact eosinophilic and parakeratotic

type of seborrheic keratosis

oral melanoacanthomas are reactive proliferations unrelated to seborrheic keratoses

Question 10

Clear cell acanthoma

Answer 10

discrete acanthoma with overlying parakeratosis

distinct trasnition between the normal epidermis and clear/pale cells in stratum spinosum

peppered with neutrophils

cells are deficient in phosphorylase, resulting in an accumulation of glycogen

Question 11

large cell acanthoma

Answer 11

discrete acanthoma composed of cells with large nuclei, typically twice the size of nuclei in the surrounding epidermis

overlying lamellar hyperkreatosis is common

can be pigmented