Case 170113-2

Eleven-year old, castrated, male cat

No clinical history was provided.

No gross description was provided.

One cross-section of haired skin is examined, in which the associated subcutis is expanded by a moderately cellular, unencapsulated, invasive, ill-defined mass of spindle cells which form blood-filled spaces, and which are infiltrated by large numbers of well-formed lymphoid follicles. The cells form finger-like projections and anastomosing trabeculae along a fibrous stroma. Occasionally, the cells form solid fascicles. Cell margins are indistinct, and the cells have small amounts of coarse, pale, amphophilic cytoplasm. Nuclei are oval and central, with coarsely stippled chromatin and a single, prominent, basophilic nucleolus. Two mitotic figures are counted in ten 400 X fields. Anisocytosis and anisokaryosis are mild to moderate. Multinucleated cells are rarely observed. Large numbers of small lymphocytes, as well as plasma cells and hemosiderin-laden macrophages, infiltrate the fibrous stroma. Along the margins of the mass, there are large numbers of individualized and coalescing, well-formed lymphoid follicles with distinct germinal centers, which contain tingible body macrophages. Superficial to the mass, within the subcutis, there are large numbers of lymphocytes, plasma cells, eosinophils, histiocytes, and fewer neutrophils.

The slide also has a section of lymph node in which the medullary space is completely effaced by a mass as described above. The lymph node has numerous well-formed lymphoid follicles.

No special stains.

Subcutis: Hemangiosarcoma

Lymph node: Metastatic hemangiosarcoma

This animal’s clinical signs of stranguria and hematuria were considered to be a consequence of the neoplasms in the penis; this neoplastic population was strongly immunoreactive to vimentin and smooth muscle actin, and was considered to be most consistent with a leiomyosarcoma. The same neoplastic population was also found in the prostate, lung, heart, spleen, and in adipose tissue adjacent to the urinary bladder. The masses frequently occluded blood vessels. Penile leiomyosarcomas are not described in dogs, however there is one report of a prostatic leiomyosarcoma. The source of the neoplasm in this case was unknown, but it was speculated that it could have originated at the prostate. There was also some discussion about the possibility that another mesenchymal tumor, such as a myofibroblastic sarcoma, could express smooth-muscle actin. The cystitis and prostatitis were likely secondary to an ascending bacterial infection. Escherichia coli was cultured from the bladder prior to euthanasia

Hayden DW, Klausner JS, Waters DJ. Prostatic leiomyosarcoma in a dog. J Vet Diagn Invest. 1999. 11(3):283-6.

McEntee, MC and Page, RL. 2001. Feline Vaccine-Associated Sarcomas. Journal of Veterinary Internal Medicine, 15: 176–182.