nasal neuroendocrine adenocarcinoma in a 9-year-old mixed-breed dog

A 9-year-old male mixed-breed dog was referred to the internal medicine service at shiraz university for investigation of increased serosanguinous nasal discharge. the dog had been experiencing sneezing and dyspnea for two months. on presentation, the dog exhibited normal vital signs and appeared bright and attentive, despite asymmetry in the rostral snout. no visible masses were noted in the external nasal cavity or nares initially. the dog had received treatment with potentiated amoxicillin and corticosteroids. routine serum biochemistry revealed elevated alp (244 u/l, ri <114 u/l) and mild hypo albuminemia (1.96 g/dl, ri 2.3-3.1 g/dl). imaging of the nasal cavity identified marked bone lysis and a soft tissue mass filling the right nasal chamber, breaching the dorsal aspect of the nasal septum and extending to the platelet. no metastatic disease was observed in the thorax. the dog underwent surgical removal of the nasal masses, and multiple incisional biopsies were taken for histopathological and cytological analysis. histopathology revealed densely cellular neuroendocrine-type infiltrative neoplastic cells, separated by fibrovascular to myofibroblastic stroma. the neoplastic cells were round to polygonal with scant eosinophilic cytoplasm surrounding slightly irregular nuclei with finely stippled chromatin and occasional small nucleoli. moderate anisocytosis and anisokaryosis were noted. despite recommendations for radiotherapy and chemotherapy, the owners declined further treatment and opted for humane euthanasia. neuroendocrine (ne) cells are widely distributed across various organs, including the genitourinary system, liver, pancreas, and tracheobronchial tree, originating embryologically from the gut. tumors of the neuroendocrine system are uncommon in dogs, particularly in the sinonasal and nasopharyngeal regions, a rarity shared with both humans and animals. these cells coexist with epithelial, neuroepithelial, and mesenchymal components in the sinonasal region. studies on nasal tumors in dogs indicate adenocarcinomas as the most prevalent carcinoma, followed by squamous cell carcinomas and transitional carcinomas. primary neoplasms in the sinonasal area of dogs are generally rare, with carcinomas predominating, followed by sarcomas of bone, cartilage, or fibrous tissue. a limitation of this case study is the absence of immunohistochemical findings. distinguishing neuroendocrine cells from lymphoma, neuroectodermal tumors, and embryonal rhabdomyosarcoma can be challenging. immunohistochemistry would be crucial to exclude lymphoma and rhabdomyosarcoma in this study.