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Adenoma/Adenocarcinoma, Perianal 31

may be attempted for nonresectable or PROGNOSIS & OUTCOME associated with only 10% of all GI
metastatic, or carcinomatosis. Prognosis depends on • In cats, the large intestine is the most
malignancies.
VetBooks.ir • Intraluminal stent placement may be pallia- • Histologic type and grade of the primary common location for intestinal adenocarci- Diseases and Disorders
• Toceranib may be helpful for maintenance
to limit blood vessel ingrowth to tumor sites.
noma, and adenocarcinoma is the most
lesion: low-grade lesions or carcinoma in situ
tive in cats with colonic obstruction.
may be completely resected.
intestine.
• Annular constrictive lesions are particularly common tumor occurring in the large
Possible Complications aggressive.
• Surgical wound dehiscence with secondary • Potential for curative resection depends on Technician Tips
peritonitis, pneumoperitoneum tumor size and location. • These patients are very ill; observe for signs
• Chemotherapy-induced neutropenia predis- • Metastatic disease and carcinomatosis are of hypotension and abdominal effusion that
poses to infection. incurable and have a poor prognosis. can indicate intestinal perforation.
• Chemotherapy-induced thrombocytopenia • In one study, cats with colonic adenocarci-
may increase tumor hemorrhage. noma treated with subtotal colectomies and SUGGESTED READING
• Chemotherapy may result in perforation of carboplatin had mild toxicity with a median Risseto K, et al: Recent trends in feline intestinal
transmural lesions. survival time of 269 days. neoplasia: an epidemiologic study of 1,129 cases
in the veterinary medical database from 1964 to
Recommended Monitoring PEARLS & CONSIDERATIONS 2004. J Am Anim Hosp Assoc 47:28, 2010.
If primary lesion can be successfully resected, AUTHOR: Barbara E. Kitchell, DVM, PhD, DACVIM
abdominal ultrasonography for metastasis or Comments EDITOR: Rance K. Sellon, DVM, PhD, DACVIM
recurrence and thoracic radiographs are indi- • The small intestine contains more than 90%
cated periodically. of the GI epithelial cell population but is

Adenoma/Adenocarcinoma, Perianal Client Education
Sheet

BASIC INFORMATION Clinical Presentation • Hyperfunction of the zona reticularis of the
adrenal gland results in elevated androgen
Definition HISTORY, CHIEF COMPLAINT levels regardless of neuter status.
Neoplastic proliferation of the hormone- • Perianal adenoma: slow-growing, nonpainful
dependent, nonsecretory perianal sebaceous mass/masses in perineal region. Ulceration DIAGNOSIS
glands, which are located circumferentially and infection can occur, but tumors usually
within the skin surrounding the anus and skin remain freely movable. Diagnostic Overview
along the caudal half of the body • Perianal adenocarcinoma: rapidly growing, The diagnosis of a perianal adenoma is suspected
firm, fixed, ulcerated mass/masses in perineal in an intact male dog presenting with a cutane-
Synonyms region. Obstipation and dyschezia can occur ous growth along the perineal region. Confirma-
Hepatoid tumor, circumanal gland tumor with larger tumors or with metastasis to tion requires histopathology, although lesions
sublumbar lymph nodes often regress in male dogs after neutering.
Epidemiology • Perianal adenomas and adenocarcinomas can
SPECIES, AGE, SEX occur anywhere along the haired skin of the Differential Diagnosis
• Perianal adenoma: older, intact male and caudal half of the body • Anal sac tumor (e.g., adenocarcinoma,
ovariohysterectomized female dogs squamous cell carcinoma, melanoma)
• Perianal adenocarcinoma: uncommon in PHYSICAL EXAM FINDINGS • Anal sac abscess
dogs; average age is 11 years • Cutaneous mass in the perineal region. The • Other cutaneous neoplasia
masses tend to be well circumscribed, • Perineal hernia
GENETICS, BREED PREDISPOSITION superficial, and may be finely lobulated or • Perianal fistula
• Perianal adenoma: Alaskan malamute, beagle, cauliflower-like in appearance.
bulldog, cocker spaniel, Siberian husky, • ± Ulceration Initial Database
Samoyed, shih tzu • ± Diffuse skin thickening • CBC, serum chemistry panel, and urinalysis
• Perianal adenocarcinoma: German shepherd, • Differentiation from anal sac disorders and to evaluate for indications of hyperadreno-
Arctic breeds (Samoyed, Alaskan malamute, perineal hernia: corticism; especially important in neutered
Siberian husky) ○ Visual inspection, as described previously dogs with perianal adenomas
○ Rectal palpation: perianal adenomas • Fine-needle aspirate cytology: the morphol-
RISK FACTORS are palpably superficial (cutaneous) and ogy of perianal gland tissue resembles
• Perianal adenoma: sexually intact males, not associated with the anal sacs; the hepatocytes. Cells are arranged in clusters.
ovariohysterectomized female dogs (estrogen pelvic diaphragm is intact and without There is abundant cytoplasm and a round,
suppresses tumor growth), hyperadrenocorti- herniation. centrally located nucleus usually exhibiting
cism with associated excess testosterone a single, large nucleolus. Cellular pleomor-
secretion Etiology and Pathophysiology phism varies and is inconsistently associated
• Perianal adenocarcinoma: neutered and intact • Perianal glands are nonsecretory sebaceous with malignancy.
males and females glands.
• Perianal glands adenoma growth is Advanced or Confirmatory Testing
ASSOCIATED DISORDERS stimulated by androgens and suppressed by • Tissue biopsy is required to distinguish
Hyperadrenocorticism, hyperandrogenism estrogens. benign from malignant disease, with

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