Forty‐three dogs affected by canine leishmaniasis (CL) with skin lesions have been studied clinically and histopathologically. Identification of leishmaniads in tissues was achieved using indirect immunoperoxidase staining. According to both macroscopic and microscopic lesions, four different dermatological patterns have been observed. Twenty‐six dogs showed alopecia and desquamation as the main skin lesions. Histologically a diffuse non‐suppurative dermatitis, with numerous leishmaniads inside macrophages was present. Ten animals showed skin ulcerations on limbs, especially over articulations. Histologically, the number of leishmaniads was very reduced. Five animals presented a generalised nodular disease. Each nodule corresponded with a focal accumulation of macrophages, multinucleated giant cells and lymphocytes, with a high number of parasites. Finally, two dogs presented generalised skin pustules. The possible pathogenesis and the differential diagnosis of each form is discussed.

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Three cases of epithelial-myoepithelial carcinoma (EMC) with coexisting areas of high grade carcinoma are reported. In two of the cases there was a previous recurrence, and in all three patients there had been a sudden increase in size before final surgery. The typical ductal and myoepithelial components of EMC showed the usual biphasic pattern and the expected immunophenotypes, with expression of wide spectrum cytokeratins, Cam 5.2 and EMA in the ductal part, and muscle-specific actin, smooth muscle actin, S-100 protein, vimentin and cytokeratins in the myoepithelial component. These areas also had a low mitotic count and low proliferation rate as measured by immunohistochemistry and by flow cytometry. Conversely, areas of high-grade tumour had the features of a large cell carcinoma, with focal mucin secretion in two cases. This high-grade component showed an epithelial immunophenotype in two cases, and was negative for all tested markers in the third one. The mitotic counts and the proliferation rates were much higher in these anaplastic areas. One of the patients died 3 months after treatment; another developed lymph node metastases 1 year later and was alive after 6 years of follow-up. The third patient was alive without evidence of disease 7 months after wide surgical resection of the tumour. The possibility of anaplastic transformation in EMC makes thorough sampling mandatory in this type of neoplasm.

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