Long-term survival of a cat diagnosed with primary hepatic neuroendocrine carcinoma treated with surgical resection and several adjuvant chemotherapies

Primary hepatic neuroendocrine carcinoma, previously referred to as carcinoid, is a malignant tumour arising from neuroendocrine cells and is a rare form of hepatic neoplasia in cats. This case report describes primary hepatic neuroendocrine carcinoma in a cat, with weight loss and vomiting as its primary clinical signs. Definitive diagnosis was made following surgical excision and histopathology of the affected liver lobes in addition to immunohistochemistry staining. Following surgery, the cat received different chemotherapy agents due to observation of progressive disease at restaging visits. The cat is currently receiving metronomic chemotherapy of cyclophosphamide and has no evidence of metastatic disease present 1009 days after initial presentation. Primary hepatic neuroendocrine carcinoma can occur in cats and should be a differential diagnosis for a hepatic mass in this species. Primary hepatic neuroendocrine carcinomas are rare in cats, and there is no standard of care for treatment in companion animals.