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Types of Cancer > OncoLink Vet > Veterinary Oncology > Tumors

Anal Sac Gland Tumors

Supported by the Savannah and Barry French Poodle Memorial Fund
Affiliation: University of Pennsylvania School of Veterinary Medicine
Last Modified: August 21, 2005

Michael H. Goldschmidt, MSc, BVMS, MRCVS, Diplomate ACVP Professor and Head, Laboratory of Pathology and Toxicology Chief, Surgical Pathology Department of Pathobiology
Frances S. Shofer, PhD, Adjunct Associate Professor of Epidemiology and Biostatistics

Introduction

The anal sacs in the dog are paired structures found on the ventrolateral aspect of the anus. They are located between the external and internal anal sphincter muscles. The normal anal sac is between 0.5cm to 1.0cm in diameter. There is a short excretory duct that lies between the anal sac and the glabrous skin of the anal area. The anal sac and the duct are both lined by keratinizing stratified squamous epithelium. Several large sebaceous glands lie at the opening of the duct into the anal sac. In the wall of the anal sac are many apocrine glands which communicate with the anal sac via a duct. The anal sac contents contain desquamated keratin, as well as sebaceous and apocrine secretions. Anal sac gland tumors arise from the apocrine glands. It is important to note that these tumors are of apocrine and NOT hepatoid or perianal glands, which are also found in this area.

• Anal Sac Gland Adenoma
• Anal Sac Gland Carcinoma
• References

Anal Sac Gland Adenoma

Definition: a benign tumor arising within the wall of the anal sac with differentiation to apocrine secretory epithelium

Synonyms: adenoma of the apocrine glands of the anal sac, perianal adenoma of the apocrine gland

This benign tumor is very rare. It cannot be differentiated on gross appearance from the malignant anal sac carcinoma. On histopathology, the tumor is well demarcated, has little cellular pleomorphism, a low mitotic activity, and consists of multiple small islands of glandular tissue which are separated by fibrovascular connective tissue.

Anal Sac Gland Carcinoma

Definition: a simple malignant tumor arising in the wall of the anal sac with differentiation to apocrine secretory epithelium

Synonyms: carcinoma of the apocrine glands of the anal sac, anal sac gland adenocarcinoma, adenocarcinoma of the apocrine gland of the anal sac, perirectal adenocarcinoma

Epidemiology