Fibrosarcoma in a domestic pigeon ( <i>Columba livia domestica</i> )

Abstract A 16‐month‐old male domestic pigeon ( Columba livia domestica ) was presented with a history of reoccurrence of a large, firm and rapidly growing subcutaneous mass on the neck region. The mass was haemorrhagic and ulcerated, causing discomfort and inability to fly. Grossly, the mass was irregular, multilobulated and firm on cut section, with areas of necrosis and haemorrhage. Fine needle aspiration cytology exhibited atypical spindle cells displaying a high nucleus‐to‐cytoplasm ratio, plump nuclei with coarse chromatin and multiple nucleoli. Microscopically, the tumour consisted of densely packed, interlacing bundles of spindle cells with marked pleomorphism, anaplasia and a high mitotic index, supporting a diagnosis of a mesenchymal tumour (malignant), which was confirmed as fibrosarcoma by Masson's trichrome staining. This case report emphasises the importance of including fibrosarcoma in the differential diagnosis of cutaneous masses in avian species.