A 62-year-old man had a neuroendocrine tumor of the rectum treated by colon resection and radiation therapy. Three years later, he experienced diplopia and right periorbital swelling and also was found to have metastasis to the liver, lung, and groin. Indium-111 OctreoScan demonstrated a mass in the right orbit. Visual acuity was no light perception in the right eye (OD) and 20/30 in the left eye (OS). There was right eye proptosis of 10 mm on exophthalmometry and decreased ocular motility in all gazes. Magnetic resonance imaging (MRI) of the orbits revealed a 30-mm well-circumscribed intraconal mass adjacent to the medial rectus muscle displacing the optic nerve medially. The lesion was isointense on T1-weighted images with moderate enhancement after contrast. Enucleation and anterior orbitotomy were performed for the painful blind eye and tumor resection, respectively. Histopathology of the resected lesion showed metastatic neuroendocrine tumor with the tumor cells staining positive for chromogranin, synaptophysin, and neuron specific enolase. At 2 years follow-up, there was no orbital recurrence of the tumor; however, there was progression of the liver, lung, and skin metastases. Despite chemotherapy (carboplatin and TP-16) and external beam radiotherapy (EBRT) of extraorbital tumors, the patient died 3 years after orbital surgery.
Patient 5 is a 61-year-old female who was diagnosed with a well differentiated G2 (Ki-67 5%) metastatic small intestine (not otherwise specified) NET in February 2010. She remained symptom free until April 2014 when she was started on monthly octreotide. In the setting of progressive disease, she subsequently received sunitinib and everolimus. She began to develop progressive diplopia and right ocular pain in August 2016. This prompted an orbital MRI which revealed bilateral recti masses in the right lateral and superior left medial muscles. She was evaluated by radiation oncology shortly thereafter and was treated with IGRT to 52Gy, which completed in October 2016. Although her right ocular pain improved, she had persistent diplopia. Her post-treatment orbital MRI in January 2017 revealed a mild increase in size of her right lateral rectus mass (Fig. a). She was then started on capecitabine in January 2017 on a two week on, one week off regimen schedule. Patient also established care with ophthalmology at this time. She achieved stable disease in her orbits with symptomatic improvement and did not demonstrate any evidence of visual field deficits. She continues capecitabine and her last MRI in July 2018 revealed ongoing shrinkage of her right lateral rectus mass (Fig. b); her recent 68Ga-DOTATATE PET/CT from October 2018 shows residual SSTR avidity within her bilateral recti muscles (Fig. c and d).