Testicular leiomyosarcoma and marked alopecia in a cryptorchid ferret (Mustela putorius furo).

A 3.5-year-old male ferret, bought as male castrated, was presented to the veterinarian with marked alopecia of back, neck, abdomen and tail, a pronounced sexual behaviour and weight loss. An inguinal mass of about 2.5 cm in diameter was diagnosed as potentially tumorous inguinal testicle by ultrasound and fine-needle aspiration. Adrenal glands and prostate were ultrasonographically unremarkable. The surgically removed cryptorchid testicle contained a greyish tumour that was histologically composed of spindle-shaped cells with elongated nuclei, embedded in a fibro-vascular stroma. Up to two mitotic figures per high power field were noted. Additionally, an interstitial cell hyperplasia and marked reactive proliferation of a collagen-rich fibrous tissue were observed. Tumour cells were positive for α-smooth muscle actin, desmin, and occasionally vimentin and S-100, leading to the diagnosis of an intratesticular leiomyosarcoma. As an adrenal-associated endocrinopathy was excluded and a complete fur recovery was observed after removal of the cryptorchid testicle the alopecia was eventually due to hormones produced by the hyperplastic interstitial (Leydig) cells.

[Peripheral keratinizing ameloblastoma in a dwarf rabbit (Oryctolagus cuniculus f. dom.)]. / Peripheres keratinisierendes Ameloblastom bei einem Zwergkaninchen (Oryctolagus cuniculus f. dom.).

A 3.5-year-old, male, neutered dwarf rabbit was presented with a history of a fast-growing gingival mass at the maxilla. The neoplasm was surgically completely excised. Histopathologically, an expansively growing, multilobulated, partially cystic, peripheral, keratinizing ameloblastoma was diagnosed. The immunohistochemical phenotyping of the tumour cells resulted in cytoplasmic labelling with various pan-cytokeratin antibodies. The cytokeratins 5/6, 7, 10 and 14 were expressed variably. Cytokeratin 20 was not detected. Vimentin was expressed in the cytoplasm of mesenchymal cells of the tumour stroma. In addition, in the nuclei of approximately 10% of the tumour cells the protein of the tumour suppressor gene p53 was expressed while in approximately 5% the proliferation marker Ki67 was expressed. Odontogenic tumours should be considered as a differential diagnosis of oral masses in rabbits.

Identification of the asexual state of Rhizopus species on histologic tissue sections in a patient with rhinocerebral mucormycosis.

Mucormycosis is an infection caused by a group of fungi in the order Mucorales in the phylum Zygomycota. The most well-known form of this disease is rhinocerebral mucormycosis, which usually develops in diabetic or immunocompromised patients. The fungal hyphal elements are easily detected in biopsy specimens by direct or histologic examination. However, the confirmatory identification of the genus or species requires culture of the specimen. This article presents a case of rhinocerebral mucormycosis in which presumptive identification of the genus was made without microbiologic cultures and was based on the extraordinarily rare appearance of fungal sporangia and sporangiospores in histologic tissue sections. Identification of these structures allowed an early and accurate diagnosis of rhinocerebral invasive mucormycosis.

Engyodontium album endocarditis.

This is the first reported case of native valve endocarditis caused by Engyodontium album. This fungus, rarely seen as a human pathogen, is separated from Tritirachium species by its lack of pigmentation and from Beauveria species by the presence of conidiogenous cells in whorls.

Giant forms of Blastomyces dermatitidis in the pulmonary lesions of blastomycosis. Potential confusion with Coccidioides immitis.

Typical yeast-phase cells of Blastomyces dermatitidis have a characteristic appearance in tissue sections. Fungal morphologic variation occurs infrequently in the lesions of blastomycosis, yet it can complicate the differential diagnosis, particularly if fresh tissue is not available for microbiologic culture. The authors report a case of pulmonary blastomycosis, confirmed by culture and direct immunofluorescence, in which some of the yeast-like cells were abnormally large. These giant yeast-like cells exceeded the size range accepted for the tissue forms of B. dermatitidis; therefore, coccidioidomycosis was considered initially in the differential diagnosis. Otherwise characteristic morphologic features of these cells, in particular multinucleation and the production of broad-based blastoconidia, helped resolve the differential diagnosis. The diagnosis can be confirmed by direct immunofluorescence or microbiologic culture.