Apocrine Ductal Adenoma

A benign tumor showing differentiation to apocrine ductal epithelium.

Gross Appearance:

Histology:
•Nodular masses
•Often involve both the dermis and subcutis
•May be central cystic degeneration
•Multilobulated
•Proliferation of a double layer of basophilic epithelial cells separated by a thin fibrous stroma
•Cells lining the lumina may have scant clear cytoplasm with small hyperchromatic nuclei
•Cells adjacent to the basal lamina zone may be more fusiform with little cytoplasm and a euchromatic nucleus
•Little cellular or nuclear pleomorphism
•Few mitoses
•In the cat, the cells that make up the bilayered epithelium appear similar with hyperchromatic nuclei and little eosinophilic cytoplasm
•Lumen formation often produces characteristic oriental letter appearance

Sex Distribution (N=407)

Sex

Status

Percent

Male	(46.4%)
43.9

intact

(13.9%)

12.0

neutered

(32.5%)

31.9

Female	(53.6%)
56.1

intact

(18.4%)

16.7

neutered

(35.2%)

39.3

(normal sex distribution)

Anatomic Location (N=393)

Site
Percent

Neck 45.8

Forelimb 9.4

Thorax 8.9

Back 7.9

Abdomen 7.1

Head 6.4

Hindlimb 6.4

Tail 4.3

Multiple 3.3

Perineum 0.5