Isabele Barbieri dos Santos

Histopatologia de lesões tumoriformes presentes na cavidade nasal de eqüídeos do Brasil

The purpose of the present study was to analyze the microscopic aspects of tumor-like masses present in the nasal cavity of equids and also to emphasize the importance of histopathological examination for determining the diagnosis. Tissue sections of tumor-like masses from the nasal cavity of 11 equids were microscopically examined. These samples were sent to the Anatomic Pathology Service of the Veterinary Medicine College from the Fluminense Federal University, Niteroi, Rio de Janeiro, from 2000 to 2004. Three cases of rhinosporidiosis, one of amyloidosis, six of nasal polyps and one of progressive ethmoid hematoma were diagnosed.

Higher sensitivity of immunohistochemistry for bona fide diagnosis of dog Leishmania (Viannia) braziliensis-driven American tegumentary leishmaniasis: description of an optimized immunohistochemistry method.

BACKGROUND The in situ detection of parasite antigens in tissue sections by immunohistochemistry (IHC) is a diagnostic alternative for human American tegumentary leishmaniasis (ATL), but has not been used for the diagnosis of cutaneous lesions in dogs with ATL. This study describes the results of IHC for the detection of amastigote forms and other Leishmania sp. antigen-positive cells and compares the results of IHC, histopathology and cytopathology for the diagnosis of canine ATL. In addition, possible cross-reactivity with sporotrichosis is analyzed. METHODS Forty paraffin-embedded biopsies and 40 smears of cutaneous lesions from dogs with ATL, confirmed by isolation and characterization of Leishmania (Viannia) braziliensis, and 40 paraffin-embedded biopsies of cutaneous lesions from dogs with sporotrichosis, confirmed by isolation of Sporothrix schenckii in culture (control group), were studied. RESULTS Immunohistochemistry was more sensitive in detecting amastigote forms than cytopathology and histopathology, with a positivity rate of 70% (n=28) versus 37.5% and 22.5% for histopathology and cytopathology, respectively. Cytoplasmic staining of mononuclear and endothelial cells was detected by IHC, which was highly specific since no cytoplasmic staining of these cells or staining of fungal structures was observed in sporotrichosis fragments. CONCLUSIONS In view of the higher sensitivity of IHC in detecting Leishmania sp. antigen and patterns of positivity for Leishmania sp. antigen compared to histopathology or cytopathology and the absence of cross-reactions with sporotrichosis, we recommend this technique for the diagnosis of canine tegumentary leishmaniasis.

Atypical feline sporotrichosis resembling vaccine-induced sarcoma: clinical and histopathological aspects

A 7-year-old Siamese cat presenting with three ulcerated cutaneous nodules in the lumbosacral region was seen at the Laboratory for Clinical Research on Dermatozoonoses in Domestic Animals in Rio de Janeiro, Brazil. Histopathological analysis showed that the lesions consisted of polyhedral and spindle-shaped voluminous mononuclear cells with loose chromatin and clearly visible nucleoli, few giant cells, and foci of coagulative and caseous necrosis — findings suggestive of a vaccine-induced sarcoma. No significant mitotic rate, cytological atypias or asteroid bodies were observed. Special histopathological staining with periodic acid-Schiff and Grocott’s silver stain demonstrated the presence of small yeast cells characterized by simple and narrow-base budding compatible with Sporothrix schenckii. Mycological culture grew S schenckii. Cytopathology was negative for yeast cells. These atypical clinical and histopathological signs support the importance of histopathological analysis with special staining techniques, in addition to mycological culture in the diagnosis of feline sporotrichosis.