A rare variant of multicentric large B-cell lymphoma with plasmacytoid and mott cell differentiation in a dog.

This report details the diagnosis and immunohistochemical characterisation of a disseminated B-cell lymphoma with a predominant Mott cell phenotype in a 5-year-old, neutered male Australian shepherd dog. The dog presented with progressive neurological signs as a result of cerebrocortical involvement.

Primary nasal histiocytic sarcoma of macrophage-myeloid cell type in a cat.

A 16-year-old neutered male Burmese cat was presented with a locally invasive nasal mass. The cytological and histological findings on incisional biopsy of this mass were suggestive of histiocytic sarcoma. Tumour cells expressed CD18, major histocompatibility complex class II, lysozyme and alpha-naphthyl acetate esterase; and lacked expression of CD3, CD79a, CD1a, CD1b, calprotectin, CD11c and E-cadherin. These findings are consistent with a myeloid-macrophage lineage. Metastasis to the bone marrow was present on necropsy examination. Histiocytic sarcoma should be considered in cats presented with primary round cell neoplasia of the nasal cavity.