Basal Cell Tumor

A benign neoplastic proliferation of cells that recapitulate the basal cell layer of the normal epidermis.

Gross Appearance:
•Nodular, intradermal mass
•May show central cystic degeneration
•Often pigmented

Histology:
•Neoplasms occur as dermal masses
•May have an association with the overlying epidermis
•Islands of neoplastic cells are present in a moderately fibrous stroma
•Cells are small, round or polyhedral, with little cytoplasm and ovoid nuclei
•Neoplastic cells show little nuclear pleomorphism and variable mitotic activity
•Central cystic degeneration of the tumor lobules may be found
•Melanophages may be present in the stroma and within the center of the cyst
•Melanin pigment is within the cytoplasm of tumor cells

Cytology:
•Small to medium-sized cells
•Very adherent, difficult to find isolated cells
•Uniform cell population
•High N:C; round nuclei, moderately dense chromatin; indistinct
•Nucleoli; small amount of blue cytoplasm
•May or may not see melanin pigment granules

Prognosis:
Good following wide excision, may recur but metastasis not reported

Breeds At Increased Risk
Breed	Odds Ratio	95% Confidence Limit	Probability
Himalayan	2.8	2.01 - 3.76	0.001
Persian	1.7	1.24 - 2.21	0.001
Domestic Long Hair	1.5	1.27 - 1.81	0.001

Breeds At Decreased Risk
Breed	Odds Ratio	95% Confidence Limit	Probability
Domestic Short Hair	0.7	0.63 - 0.82	0.001

Sex Distribution (N=1578)

Sex Status
Percent

Male
(46.4%)

51.1%

intact
(13.9%)

16.1

neutered
(32.5%)

35.0

Female
(53.6%)

48.9%

intact
(18.4%)

13.9

neutered
(35.2%)

35.0

(normal sex distribution)

Anatomic Location (N=1477)

Site
Percent

Neck 22.5

Head 17.9

Forelimb 17.2

Hindlimb 10.7

Thorax 10.7

Abdomen 10.2

Back 7.1

Tail 2.1

Multiple 1.3

Perineum 0.3