Feline progressive histiocytosis (FPH) is an uncommon and infrequently reported cutaneous histiocytic proliferative disorder, whose clinical presentation is solitary or multiple cutaneous nodules and papules, with late-course internal metastasis. We describe herein the clinical, epidemiologic, histologic, and immunohistochemical features of this entity, and document the outcome of FPH based on a retrospective study of 26 cases. Female and male cats were affected equally. Lesions were evident either as solitary (16 of 26 cases) or multiple (10 of 26 cases) nonpruritic and alopecic nodules or plaques, preferentially located on the legs and extremities (73%). Follow-up was complete for 19 cats, and ranged from 41 to 1,449 d. Nine died of FPH with a median overall survival of 96 d (range: 41–238 d). The disease recurred in 14 cats after surgical excision of the nodules, and the median disease-free survival was 175 d (range: 21–1,449 d). Five of the 26 cats were alive at the end of the study, and 4 had no progression of the disease. Histologically, lesions were characterized by poorly circumscribed, unencapsulated histiocytic infiltration of dermis and subcutis. Epitheliotropism was observed in 11 (42%) cats. Atypical histiocytes diffusely and consistently expressed MHC II, CD18, and Iba1. Statistically significant higher E-cadherin expression was observed in epitheliotropic cases compared to non-epitheliotropic cases. A negative correlation between overall survival and proliferation index was evident, thus suggesting Ki67 as a promising prognostic marker.

No abstract

An 8-y-old, intact female degu (Octodon degus) was presented with a slow-growing mass on the tail tip. The mass was completely removed by partial caudectomy. Histologically, the last coccygeal vertebra was replaced by a lobulated neoplasm composed of large clear polygonal cells embedded in a myxoid alcian blue-positive matrix with highly vacuolated cytoplasm (physaliferous cells) and intracytoplasmic periodic acid-Schiff-positive granules. The neoplasm exhibited the morphologic features of a "classic" chordoma of humans, which is 1 of 3 distinct chordoma subtypes. Immunohistochemistry revealed dual expression of cytokeratin AE1/AE3 and vimentin, consistent with a diagnosis of chordoma. Chordomas are uncommon slow-growing neoplasms in humans and animals, arising from notochordal remnants. Depending on their subtype and location, they can have a high local recurrence rate and metastatic risk. Chordoma should be included in the differential diagnosis of a soft tissue mass on the tail of a degu, similar to the clinical situation in ferrets.

No abstract

Ureteral pseudodiverticulosis is an unusual acquired abnormality in humans and dogs. This report describes the first feline case of ureteral pseudodiverticulosis, associated with right retrocaval ureter and malposition of the uretero-vesical junctions, in the context of pyelonephritis. The coexistence of pseudodiverticulosis with other urinary abnormalities suggested that this lesion should be considered in other patients with urinary pathology.