ABSTRACT
INTRODUCTION AND IMPORTANCE: HPV-related carcinoma with adenoid cystic carcinoma-like features currently known as HPV-related multiphenotypic sinonasal carcinoma (HMSC) is a rare distinct head and neck high-risk HPV-related carcinoma. The high-risk HPV subtypes implicated are particularly type 33,35 and 56. So far this is the first reported rare case of a variant of sinonasal carcinoma in Tanzania. CASE PRESENTATION: We present a 59-year old female who presented with a history of right-sided nasal obstruction and intermittent epistaxis for about one year and later on had ipsilateral proptosis. A provisional diagnosis of advanced right-sided malignant sinonasal tumor was made. Trans nasal biopsy revealed HMSC. CLINICAL DISCUSSION: The patient had a right sided fixed neck mass that measured about 7.5 × 8.2 cm. Magnetic resonance imaging (MRI) of the paranasal sinuses revealed a T1 weighted contrasted images that showed a huge extensive enhancing mass (estimated to measure 4.5 × 4.4) involving the nasal cavity, bilateral ethmoid sinuses, frontal and sphenoid sinuses and also the tumor exhibit intracranial extension (anterior cranial fossa) and tend to compress medial walls of both orbits though more marked on the right side. Histopathology and immunohistochemistry confirmed HPV-related multiphenotypic sinonasal carcinoma. The disease was staged to be T4bN3aM0 and the patient was referred for palliative chemoradiation. CONCLUSION: Although HMSC presents at advanced stage in close to half of cases and has a high-grade histological appearance it paradoxically exhibits a relatively indolent manner with frequent local recurrences. Prompt histopathological diagnosis is important to prevent metastases and HMSC-related deaths.