Orbital Involvement as an Initial Presentation of Sinonasal Neuroendocrine Carcinoma

Purpose: To present a case of sinonasal neuroendocrine cancer initially manifesting with orbital involvement. Case summary: A 63-year-old female patient visited a neuro-ophthalmologic clinic due to a 3-week history of decreased visual acuity (VA), color vision abnormalities, and swelling of the upper eyelid in right eye. Best-corrected VA (BCVA) in the right eye was 0.8. Clinical findings included a relative afferent pupillary defect, restricted eye movement in lateral, superior, and medial gaze, and exophthalmos in the right eye. Wide-field fundus photography and optical coherence tomography indicated swelling of right optic disc. Magnetic resonance imaging was performed revealing a mass invading nasal cavity, sinus, and right orbital apex, and compressing the medial rectus, inferior rectus, superior oblique, and optic nerve. An otolaryngological nasal biopsy was conducted and immunohistochemical staining showed positive results for Ki-67, NSE, p16, P-53, and CD56, leading to a diagnosis of small cell neuroendocrine carcinoma with an irreducible tumor stage. Prior to initiation of treatment (concurrent chemoradiotherapy, CCRT), there was rapid worsening of VA and eye movement in the right eye. CCRT commenced alongside high-dose steroid treatment. One month following treatment, the BCVA of the right eye improved and protrusion of the right eye resolved. Six months after starting CCRT, a contrast-enhanced orbital computed tomography scan showed no residual lesion. The BCVA of the right eye stabilized at 0.3 with complete recovery of color vision and eye movement. Conclusions: Neuroendocrine cancer should be considered as a possible diagnosis in cases of rapidly progressing compressive optic neuropathy.