September 2016



Signalment (JPC 2031602):  A dog

HISTORY:  This large mass was located lateral to the anus.

HISTOPATHOLOGIC DESCRIPTION:  Anal sac:  Effacing subepithelial connective tissue, replacing normal apocrine glands, infiltrating and compressing surrounding muscle bundles, and compressing adjacent moderately ectatic apocrine glands is an unencapsulated, multilobulated, densely cellular neoplasm partially surrounding the anal sac and composed of bimorphic polygonal cells with glandular portions arranged in variably sized islands and tubuloacini, and more solidly cellular areas with multifocal rosette and pseudorosette formation. Neoplastic cells are cuboidal to columnar with variably distinct borders, moderate amounts of eosinophilic cytoplasm, and multifocal apical blebbing and are supported by a coarse fibrovascular stroma. Nuclei are round to oval, located basally within tubuloacinar arrangements, and have finely stippled chromatin with 1-2 nucleoli. There is mild anisokaryosis and the mitotic rate averages 2-3 per high power field. Multifocally glandular lumina contain eosinophilic amorphous secretory product occasionally mixed with sloughed neoplastic cells and necrotic cellular debris. Neoplastic cells form a large single duct lined by multiple layers of columnar neoplastic cells and is filled with low numbers of erythrocytes, sloughed neoplastic cells, hemosiderin-laden macrophages, and fibrous connective tissue with necrotic cellular debris. Neoplastic cells are found within dilated lymphatics. There is multifocal scattered single cell necrosis and hemosiderin-laden macrophages. Multifocally in the periglandular and subepithelial connective tissue surrounding the neoplasm, there are moderate numbers of lymphocytes, plasma cells, and fewer eosinophils. Subjacent to the hyperpigmented and mildly hyperplastic anal sac epithelium are multifocal melanin-laden macrophages (pigmentary incontinence).

MORPHOLOGIC DIAGNOSIS:  Anal sac:  Adenocarcinoma of the apocrine glands of the anal sac, breed not specified, canine.

CONDITION:  Adenocarcinoma of the apocrine glands of the anal sac

SYNONYMS:  Adenocarcinoma of the apocrine glands of the anal sac (AAGAS)

                          Anal sac gland carcinoma (ASGC)

                          Carcinomas of the apocrine glands of the anal sac (CAGAS)

                          Anal sac apocrine gland adenocarcinoma (ASAGAC)











  1. Capen CC. Endocrine glands. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 3. 6th ed. Philadelphia, PA:Elsevier; 2016:308.
  2. Capen CC. Tumors of the endocrine glands. In: Meuten DJ, ed. Tumors in Domestic Animals. 4th ed. Ames, IA: Iowa State University Press; 2002:672-679.
  3. Capen CC, La Perle KM. Endocrine system. In: McGavin MD, Zachary JF, eds. Pathologic Basis Veterinary Disease.  6th ed. St. Louis, MO: Mosby; 2017:719.
  4. Cockerell GL, Cooper BJ. Disorders of cell growth and cancer biology. In: Slauson DO, Cooper BJ, eds. Mechanisms of Disease a Textbook of Comparative General Pathology.3rd ed. St. Louis, MO: Mosby; 2002:356-357.
  5. Ferguson DC, Hoenig M: Endocrine system. In: Latimer KS, Mahaffey EA, Prasse KW , eds. Duncan and Prasse’s Veterinary Laboratory Medicine: Clinical Pathology. 5th ed. Ames, IA: Iowa State University Press; 2011:300-301.
  6. Goldschmidt MH, Dunstan RW, Stannard AA, von Tscharner C, Walder EJ, Yager JA. Schulman FY, ed. Histological Classification of Epithelial and Melanocytic Tumors of the Skin of Domestic Animals. 2nd series, Vol. 3. Washington, DC: Armed Forces Institute of Pathology; 1998:31.
  7. Goldschmidt MH, Hendrick MJ. Tumors of the skin and soft tissues. In: Meuten DJ ed. Tumors in Domestic Animals. 4th ed. Ames, IA: Iowa State Press; 2002:74-76, 674-679.
  8. Parry NM. Anal sac gland carcinoma in a cat. Vet Pathol. 2006;43:1008-1010.
  9. Pieper JB, Stern AW, LeClerc SM, Campbell KL. Coordinate expression of cytokeratins 7 and 14, vimentin, and Bcl-2 in canine cutaneous epithelial tumors and cysts. J Vet Diag Inv. 2015: 27(4): 497-503.
  10. Polton GA, Brearley MJ. Clinical stage, therapy, and prognosis in canine anal sac gland carcinoma. J Vet Intern Med. 2007;21(2):274-280.
  11. Suzuki K, Morita R, Nomura K, Shibutani M, Mitsumori K. Immunohisochemical characterization of neuroendocrine differentiation of canine anal sac glandular tumors. J Comp Pathol. 2013;149(2-3):199-207.

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