Sinonasal Adenoid Cystic Carcinoma Presenting as a Retroorbital Mass: A Case Report.

Although sinonasal adenoid cystic carcinoma (ACC) mainly originates from the salivary glands and lacrimal gland, approximately 10-25% of cases may arise from the sinonasal cavity and paranasal sinuses. Orbital involvement typically occurs due to local spread. Only a few cases of isolated orbital ACC without another primary focus have been documented. This report aims to describe a case of sinonasal ACC presenting as a retroorbital mass, raise awareness of this tumour and its rare presentation among both ophthalmologists and otolaryngologists, and provide brief information on its treatment. A 74-year-old female who presented to an external centre with progressive periorbital oedema, congestion, proptosis, and exotropia in her right eye for approximately 4 months was referred with a right retrobulbar mass. During the initial examination, the best-corrected visual acuity was 0.05 in the right eye (OD) and 0.8 in the left eye (OS). There was no significant pathology in the anterior or posterior segments. Eye movements were normal in the OS and moderately restricted in the OD, particularly in upgaze. She reported no otorhinolaryngological complaints, and her examination was normal except for a polyp-like lesion extending from the middle to the inferior meatus. Maxillofacial and orbital magnetic resonance imaging revealed a mostly homogeneous malignant soft tissue lesion extending from the retro-orbital area to the orbital apex, ethmoid cells, and nasal cavity. The patient underwent tumour excision via an inferior transconjunctival approach and endoscopic sinus surgery. Both nasal and intraorbital surgical excision specimens were consistent with ACC on histopathological examination.