[Non-epitheliotropic B-cell lymphoma with atypical spindle cell morphology in a Weimaraner dog].

The case report describes a very rare cutaneous non-epitheliotropic B-cell lymphoma in an 11-year-old male Weimaraner dog, which presented with multiple cutaneous proliferations. In addition to numerous cytoplasmic fragments of lymphatic cells, the cytological examination of a fine-needle aspirate taken from a skin nodule revealed a population of pleomorphic plump to spindle-shaped cells with round to oval nuclei, fine chromatin structure, moderate amounts of a lightly basophilic cytoplasm and predominantly indistinct cell boundaries. These findings suggested a possible cutaneous spindle-cell lymphoma, thus a biopsy was taken. In the histopathological examination, the cells displayed no epitheliotropism and immunohistochemically they were positive for multiple B-cell markers. In addition to the rarity of cutaneous non-epitheliotropic B-cell lymphomas per se, the special feature of this case is the atypical spindle-cell morphology of the lymphatic cells. A spindle-cell variant of cutaneous B-cell lymphoma has to date only been described in human medicine.