Amelanotic melanoma in the nasopharynx of a shih tzu dog: case report

Abstract

Introduction – Melanoma of the upper airways in dogs is a rare neoplasm, characterized by aggressive biological behavior and a high metastatic potential. Clinical signs are often nonspecific, including dyspnea, nasal discharge, and respiratory obstruction, which makes early diagnosis challenging. Therefore, diagnostic confirmation relies on complementary examinations, particularly imaging studies and histopathological evaluation, which are essential for appropriate therapeutic planning. Complete surgical excision remains the treatment of choice, and continuous follow-up is crucial to monitor recurrence, clinical progression, and quality of life. Case Report – A 12-year-old Shih Tzu dog was presented with nocturnal dyspnea and respiratory obstruction. Diagnostic examinations revealed moderate bronchopathy, nasopharyngeal stenosis, and a nasopharyngeal polyp, associated with inflammatory rhinitis and brachycephalic airway changes. Due to the lack of response to clinical treatment, surgical removal of the mass was performed, and the tissue was submitted for histopathological analysis. The patient showed good postoperative recovery and was discharged after three days. Histopathological examination identified an amelanotic melanoma. The owner opted not to pursue chemotherapy, and the patient remained clinically stable after four months of follow-up. Discussion – Melanomas of the airways and oral cavity in dogs are predominantly malignant and metastatic, occurring mainly in elderly animals, with no sex predilection. Clinical variability highlights the importance of complementary diagnostic tests, especially histopathology, for achieving an accurate diagnosis. Treatment is primarily based on surgical excision and may be combined with adjuvant therapies. Conclusion – Early diagnosis and appropriate treatment are decisive factors for improved prognosis and effective clinical management.