Compressive optic neuropathy caused by sinonasal adenosquamous carcinoma with orbital extension: A case report

PURPOSE: Adenosquamous carcinoma (ASC) of the head and neck, specifically sinonasal ASC, is a rare and aggressive malignancy with metastasis occurring in 80% of patients in its initial reporting; sinonasal ASC with orbital extension has rarely been reported in literature. Despite treatment, ASC carries a poor prognosis with a 5-year survival of approximately 22%, with 50% dying within 23 months.(10) Mucoepidermoid carcinoma (MEC) and ASC have similar morphologic features. It is imperative to distinguish these two entities apart as the biologic behavior and prognosis of ASC is much worse than that of poorly differentiated MEC and squamous cell carcinoma. This case provides a rare presentation of a secondary orbital tumor, ASC with orbital extension, that manifests with ocular symptoms and is therefore relevant to practitioners in the field of ophthalmology while reviewing the histology of ASC with the goal of distinguishing the entity from its differential diagnoses. OBSERVATION: To further understand the natural history of this unusual tumor, we report a case of adenosquamous carcinoma in a 76-year-old female who presented with a three-day history of left-sided: vision loss (worse centrally and nasally), afferent pupillary defect, esotropia and abduction deficit, cervical lymphadenopathy and an extraconal mass on MRI producing a compressive optic neuropathy. We provide photography that demonstrates the patient's presentation, histologic slides provided via biopsy of the malignancy, and radiologic findings on magnetic resonance imaging, all of which support the diagnosis. CONCLUSIONS/IMPORTANCE: This case adds to the limited literature of sinonasal adenosquamous carcinoma while exploring orbitotomy techniques for adequate extraconal mass biopsies of the entity. Our manuscript reviews key histological findings of ASC provided by the patient's biopsies and details how to differentiate the cancer from other pathologies, like MEC; A differentiation that proves vital for practitioners due to the widely differing prognosis of the two pathologies. We present the first case of sinonasal ASC with orbital extension causing ophthalmologic symptoms.