Thymofibrolipoma in a labrador retriever.

While thymomas are uncommon but well-known mediastinal masses, collagen-rich variants are exceedingly rare. Thymofibrolipoma and sclerosing thymoma tumor variants have been recently recognized in medical pathology, and thymofibrolipoma has been only rarely reported in dogs. A cranial thoracic mass was identified in a 6-year-old Labrador Retriever that was characterized by robust collagenous stroma dissected by thin cords of cytokeratin-positive neoplastic epithelial cells and bordered by mildly pleomorphic epithelial cells with occasional lymphocytic aggregates and rare Hassall corpuscles. To the authors' knowledge, this is only the second report of thymofibrolipoma in veterinary medicine and the first to describe a variant with a mitotically active and relatively pleomorphic, adjacent thymic epithelial population.

Clinical, pathological and immunohistochemical study of feline mammary fibroepithelial hyperplasia following a single injection of depot medroxyprogesterone acetate.

Feline mammary fibroepithelial hyperplasia (FMFH) following a single injection of depot medroxyprogesterone acetate (MPA) was observed in eight intact young queens. The repository compound is marketed as a veterinary product by a local pharmaceutical company with an indication for contraception in cats. The drug was administered according to the recommended doses and injection frequencies. Serum hormone assays performed immediately before neutering and 3 weeks after neutering detected persistently high levels of progesterone suggesting that depot MPA was still exerting its influence. No corpora lutea were found in those cases ruling out ovaries as the main site of progesterone. Immunohistochemistry performed on the hyperplastic mammary glands detected progesterone receptors in the nuclei of ductal cells, and growth hormone (GH) and insulin-like growth factor-I (IGF-I) in the cytoplasm of ductal epithelium. Overdosing should be considered here as the animals received at least 10 mg/kg of depot MPA in a single injection. Progestin-induced local synthesis of GH and IGF-I in mammary epithelial cells is suggested as one of the pathogenic mechanisms involved in the development of FMFH.

Recurrent urethral fibroepithelial polyps in a golden retriever.

A 2 yr old castrated male golden retriever was referred multiple times over a period of 7.5 yr for stranguria, pollakiuria, urinary incontinence and urinary outflow obstructions due to urethral polyps. Diagnostic imaging modalities used to identify polyps included abdominal ultrasound, excretory urography, double-contrast retrograde urethrocystograms, and urethrocystoscopy, which revealed multiple filling defects within the proximal and prostatic urethra. Multiple cystotomies and endourologic procedures were performed to remove the multiple fibroepithelial polyps within the proximal and prostatic urethra. Urinary incontinence resulted from treatments, but did respond to phenylpropanolamine. Medical treatment consisted of a nonsteroidal anti-inflammatory drug, which appeared to decrease the recurrence of the polyps over time. Urethral polyps are an uncommon cause of urinary outflow obstruction and do not usually recur after removal. This case illustrates an uncommon clinical presentation and the difficulties encountered in treatment over an expanded time frame.

Fibroepithelial polyps of the vagina in bitches: a histological and immunohistochemical study.

The histological and immunohistochemical features of 13 cases of suspected vaginal fibroepithelial polyps are reported. The characteristic microscopical features of these lesions were an abundant oedematous or fibrous stroma containing spindle-shaped and stellate cells and the presence of variable inflammation and haemorrhage. There was often a superficial layer of compressed tissue, but the stroma in the peripheral areas of the masses was generally more loosely arranged than in central areas. The connective tissue cells expressed vimentin and desmin, but did not express smooth muscle actin or calponin. Individual cases had additional changes including granulomatous inflammation, epithelial dysplasia suggestive of papillomavirus infection and a lesion resembling phyllodes tumour in women.

Fibroepithelial hamartoma in a domestic pig.

This case report is the first description of a fibroepithelial hamartoma in a pig. The dysplasia, which covered half of the face of the newborn piglet, did not increase in relative size until the animal was euthanatized at 6 months of age. Histologic examination revealed a moderate orthokeratotic hyperkeratosis with variable degrees of epithelial proliferation. The main body of the dysplasia consisted of collagenous fibers. In addition, some proliferating small blood vessels as well as focally gathered dilated apocrine glands were evident. Given morphologic and clinical features, the diagnosis of a hamartoma seemed to be justified.

Ureteral fibroepithelial polyp in an owl monkey (Aotus nancymae).

Ureteral fibroepithelial polyps are benign mesodermal tumors in humans that occur predominantly in the proximal ureter. During a routine necropsy of a wild-caught, research naïve, adult, male, Aotus nancymae, the left ureter just distal to the renal pelvis contained a pedunculated, lobulated neoplasm with a narrow stalk at the base projecting into the lumen. The left renal pelvis was found to be mildly dilated. The histologic characteristics of the ureteral mass were consistent with a fibroepithelial polyp. To our knowledge, this is the first report describing a ureteral fibroepithelial polyp in a nonhuman primate.

Ureteral fibroepithelial polyps in four dogs.

Four dogs with ureteral fibroepithelial polyps, ranging from 9-12 years of age, are presented in this report. The patients presented with urinary incontinence, urinary tract infection, and/or polydypsia and pollakiuria. All dogs were intact at the time of diagnosis or for the majority of their lives and three were male. Various diagnostic procedures were performed including ultrasonography, contrast radiography, and nuclear scintigraphy. Not all procedures were performed in all patients. Findings included ureteral dilation proximal to the level of an intraluminal mass and ipsilateral hydronephrosis. Unilateral ureteronephrectomy was performed in three dogs with masses in the proximal ureter; ureteral resection and anastamosis was performed in the remaining patient with a mass located in the distal ureter. The same pathologist (RAP) reviewed all four lesions. The lesions appeared polypoid and were attached to the ureteral wall by a thin stalk. Histopathologically, they contained a superficial layer of well-differentiated transitional epithelial cells overlying a prominent fibrovascular stroma with a mild (three dogs) or marked (one dog) degree of lymphoplasmacytic inflammation. This disease may represent a benign neoplasm or a chronic inflammatory reaction and has a good prognosis with surgical removal. Its histopathological characteristics, higher incidence in males, and location more commonly within the upper third of the ureter is remarkably similar to the disease in humans.