Epidermal Neoplasms

Question 1

Types of BCC

Answer 1

Superficial

Nodular

Micronodular

Keratotic

Basosquamous

Sclerosing/morpheaform

Infiltrative

Fibroepithelioma of Pinkus

Adenoid cystic

Question 2

BCC Features and DDX

Answer 2

Palisading

Mucinous stroma

Clefting

Mitoses and apoptotic figures (distinguishes from trichepithelioma and other benign adnexal tumors)

Question 3

Answer 3

Fibroepithelioma of pinkus

Question 4

Answer 4

AK

(adnexal sparing)

Question 5

Answer 5

Bowen’s disease

Spares basal layer (“eyeliner sign”)

Involves follicles (unlike AK)

Question 6

Answer 6

Acantholytic AK

Question 7

SCC variants

Answer 7

1. Verrucous carcinoma (HPV)
2. Acantholytic or adenoid SCC
3. Spindle cell and sarcomatoid SCC (HMWCK: CK5/6 or 34ßE12 and p63 to distinguish from AFX, spindle cell melanoma, and LMS)
4. Clear cell and signet ring cell SCC (glycogen or degenerative changes)
5. Keratoacanthoma (putative SCC) - does have infiltrative borders

Question 8

Answer 8

Spindle cell SCC

Question 9

Answer 9

Basaloid SCC

Question 10

Answer 10

Clear cell SCC

Question 11

Answer 11

Adenosquamous SCC

Question 12

Answer 12

Acantholytic SCC

Question 13

SK variants

Answer 13

1. Verrucoid
2. Clonal
3. Irritated/inverted (inverted follicular keratosis)
4. Pigmented
5. Inflammed

Question 14

Answer 14

Inverted follicular keratosis

• Grows down a hair follicle
• Squamous eddies tend to be particularly prominent
• Otherwise, the features are those typical for irritated seborrheic keratosis, namely:
  
  • Basal and sqamous proliferation with hyperkeratosis, papillomatosis and horn cysts (general features of seborrheic keratosis)
  • Exocytosis
  • Apoptosis
  • Acantholysis
  • Scale-crust formation
  • Spongiosis
  • Trichilemmal keratinization

Question 15

Answer 15

Benign lichenoid keratosis (BLK)/lichen planus-like keratosis

• Usually on chest/arms
• dense band-like infiltrate with PK, dyskeratotic cells
• often adjacent to lentigo or SK

Question 16

Answer 16

Epidermal nevus

Usually children

head and neck, UE

Hyperkeratosis, acanthosis, papillomatosis (may look like SK or acanthosis nigricans)

Question 17

Answer 17

Clear cell acanthoma

• Acanthosis
• psorisiform epidermal hyperplasia
• Pale-staining keratinocytes (PAS+ due to glycogen) with mild spong
• occasional neut abscesses

Question 18

Epidermoid cyst aka

Answer 18

EIC, epidermoid cyst

has granular layer

Question 19

Pilar cyst AKA

Histo

Location

Answer 19

Isthmus-catagen cyst, ticholemmal cyst, “sebaceous” cyst

Lacks granular layer or minimal layer

Can have calcs

Scalp usually

Question 20

Answer 20

Steatocystoma multiplex

undulating squamoid epithelium with corrugated eosinophilic lining

Often has underlying sebaceous glands or follicles

lack keratin debris

Question 21

Answer 21

Hydrocystoma

• Head and neck (eyelid)
• mostly apopcrine (few are eccrine)
• Flattened to columnar 1-2 cell lining
• Snouting, decapitation