Ch. 3 - Malignant tumors of the epidermis

Question 1

Actinic keratosis

Answer 1

Crowded, disordered, and atypical epidermal keratinocytes arising from a broad-budding basal layer. Usually with solar elastosis. Can have overlying “malignant horn” of parakeratotic stratum corneum.

Question 2

Acantholytic actinic keratosis

Answer 2

Crowded, disordeed, atypical epidermal keratinocytes with acantholysis in areas of atypia. Can have overlying “malignant horn” and complex epidermal budding.

Question 3

Lichenoid actinic keratosis

Answer 3

Crowded, disordered, atypical epidermal keratinocytes with areas of lichenoid interface dermatitis. Can have overlying “malignant horn”.

Question 4

Hypertrophic actinic keratosis

Answer 4

Crowded, disordered, atypical epidermal keratinocytes with acanthosis. Often has complex epidermal budding. Has prominent overlying “malignant horn”

Question 5

Bowenoid actinic keratosis

Answer 5

Focal full-thickness atypia without anaplasia, nesting, buckshot scatter, or full-thickness follicular involvement.

Question 6

Bowen’s disease

Answer 6

Full-thickness atypia with loss of normal maturation. Follicular involvement, atypical nests, intraepidermal buckshot, malignant horn.

*essentially squamous carcinoma in situ)

Question 7

Distinguish between Bowen’s disease and Paget’s disease or melanoma.

Answer 7

In Bowen’s disease, the malignant keratinize can keratinize and become part of the stratum corneum.

Bowen’s disease is PAS+ (diastase sensitive) and CEA- while Paget’s is PAS+ (diastase resistant) and CEA+.

Question 8

Squamous cell carcinoma

Answer 8

Atypical keratinocytes invading the dermis with acantholysis and desmoplasia. Look for nodular lymphoid aggregates. Do keratin immunostaining,

Question 9

Verrucous carcinoma

Answer 9

Well-differentiated glassy eosinophilic squamous epithelium with blunt, rounded borders.

Question 10

Spindled squamous cell carcinoma

(differential diagnosis?)

Answer 10

Atypical spindle cells abutting the epidermis.

SLAM: Squamous cell carcinoma, leiomyosarcoma, atypical fibroxanthoma, melanoma

Question 11

Keratoacanthoma

Answer 11

Keratin-filled crater with invasive proliferation of glassy red keratinocytes. Neutrophilic & eosinophilic infiltrate. Hypergranulosis and pseudoepitheliomatous hyperplasia. Never acantholysis.

Question 12

What is the natural history of keratoacanthomas?

Answer 12

Grow rapidly (especially after biopsy) and can involute spontaneously.

Question 13

Distinguish between keratoacanthoma and squamous cell carcinoma.

Answer 13

Keratoacanthoma: Eosinophils and neutrophils. Central hypergranulosis and pseudoepitheliomatous hyperplasia. Terminal differentiation.

Squamous cell carcinoam: Plasma cells. Peripheral hypergranulosis and pseudoepitheliomatous hyperplasia. Invades eccrine glands.

Question 14

Regressed keratoacanthoma

Answer 14

Crater filled with keratin and outlined by thin wall of involuted epithelium.

Question 15

Basal cell carcinoma

Answer 15

Blue islands of basaloid cells with peripheral palisading. Retraction artifact and fibromyxoid stroma.

Question 16

Superficial multifocal BCC

Answer 16

Multifocal blue buds with distinctive fibromyxoid stroma displacing solar elastosis downward.

Question 17

Nodular BCC

Answer 17

Nodular blue islands with peirpheral palisading, retraction artifact, distinctive fibromyxoid stroma.

Question 18

Micronodular BCC

Answer 18

Small blue islands with distinctive fibromyxoid stroma surrounding individual islands (but with normal dermis between). Aggressive worm-like growth.

Question 19

Morpheaform BCC

Answer 19

Thin infiltrating strands of basaloid cells with sclerotic stroma and tadpole-like islands with small horn cysts.

Initially resembles scar but deeply invasive.

Question 20

Infiltrative BCC

Answer 20

Spiky growth pattern, with fibroblast-rich stroma and common perineural extension. Resembles stroma of trichoepithelioma.

Question 21

Infundibulocystic BCC

Answer 21

Pink strands and blue buds of tumor. Horn cysts and fibromyxoid stroma. Closely resembles basaloid follicular hamartoma.

Question 22

Fibroepithelioma of Pinkus

Answer 22

Anastomosing pink epithelial strands in ample fibromyxoid stroma with visible ducts. Blue basaloid buds at the tips and periphery of strands.

Question 23

Adenoid BCC

Answer 23

Blue islands with an adenoid pattern. Usual peripheral palisading, fibromyxoid stroma, and retraction artifact.

Question 24

Paget’s disease

Answer 24

Intraepidermal large cells with ample amphophilic cytoplasm. Atypical cells crush the basal layer and may “spit out” into the stratum corneum.

Question 25

Paget’s disease

(immunostaining)

Answer 25

CK7+

CEA+

S100-

PAS+, diastase resistant (sialomucin)

Question 26

Lymphoepithelioma-like carcinoma

Answer 26

Keratin-positive atypical epithelial cells with surrounding lymphocytes, mimics a germinal center or lymphoma. EBV-.

Question 27

Answer 27

Actinic keratosis

Question 28

Answer 28

Acantholytic actinic keratosis

Question 29

Answer 29

Lichenoid actinic keratosis

Question 30

Answer 30

Hypertrophic actinic keratosis

Question 31

Answer 31

Bowenoid actinic keratosis

Question 32

Answer 32

Bowen’s disease

Question 33

Answer 33

Bowen’s disease

Question 34

Answer 34

Bowen’s disease

Question 35

Answer 35

Clear cell change in Bowen’s disease

Question 36

Answer 36

Well-differentiated invasive squamous cell carcinoma

Question 37

Answer 37

Verrucous carcinoma

Question 38

Answer 38

Spindled squamous cell carcinoma

Question 39

Answer 39

Keratoacanthoma

Question 40

Answer 40

Regressed keratoacanthoma

Question 41

Answer 41

Superficial multifocal BCC

Question 42

Answer 42

Nodular BCC

Question 43

Answer 43

Micronodular BCC

Question 44

Answer 44

Morpheaform BCC

Question 45

Answer 45

Infiltrative BCC

Question 46

Answer 46

Infundibulocystic BCC

Question 47

Answer 47

Fibroepithelioma of Pinkus

Question 48

Answer 48

Extramammary Paget’s disease

Question 49

Answer 49

Adenoid BCC

Question 50

Answer 50

Lymphoepithelioma-like carcinoma