Apocrine Carcinoma

A simple malignant tumor showing differentiation to apocrine secretory epithelium.

Gross Appearance:
•Variable, nodular intradermal mass
•Infiltrates deeper tissue
•Erosive, ulcerated, hyperemic
•Lesion mimics an eczematous dermatitis

Histology:
•May have a solid, tubular or cystic morphology
•Cystic tumors may show papillae extending into the cyst lumina
•Dermal and subcutaneous infiltration, often with an accompanying desmoplastic response, may be observed
•Degree of differentiation of the tumor cells is quite variable
•Well differentiated tumors have an abundant eosinophilic cytoplasm
•May show apical blebing, large ovoid euchromatic nuclei with prominent nucleoli
•May exhibit modest nuclear and cellular pleomorphism and mitotic activity
•Can be differentiated from the benign tumors by their invasive nature
•At the opposite end of the spectrum the tumor cells are very pleomorphic and anaplastic, but the eosinophilic cytoplasm of the tumor cells is retained
•These tumors often evoke a strong desmoplastic host response
•Invasion of dermal lymphatics by tumor cells is a relatively common occurrence, with metastasis to regional lymph nodes and lungs

Cytology:
•Moderately large to large cells
•Occasionally isolated, generally found within adherent cell clusters and rosettes
•Moderate anisocytosis
•Moderately high to very high N:C
•Round nuclei; fine to moderately coarse ropy chromatin; variably sized prominent nucleoli
•Variably vacuolated light blue cytoplasm

Prognosis:
Very guarded; often have lymph node and pulmonary metastasis

Breeds At Increased Risk
Breed	Odds Ratio	95% Confidence Limit	Probability
Siamese	2.5	1.56 - 4.02	0.001

Breeds At Decreased Risk
Breed	Odds Ratio	95% Confidence Limit	Probability
Domestic Short Hair	0.6	0.41 - 0.79	0.001

Sex Distribution (N=213)

Sex Status
Percent

Male
(46.4%)

40.4

intact
(13.9%)

8.5

neutered
(32.5%)

31.9

Female
(53.6%)

59.6

intact
(18.4%)

21.6

neutered
(35.2%)

38.0

(normal sex distribution)

Anatomic Location (N=205)

Site
Percent

Neck 34.6

Thorax 14.1

Abdomen 14.1

Perineum 9.3

Head 7.8

Forelimb 7.3

Hindlimb 4.9

Back 3.9

Tail 2.0

Multiple 2.0