Bilateral Poorly Differentiated Adenocarcinoma of the Lacrimal Gland With Tumor Regression After Treatment With Pembrolizumab.

An 85-year-old man presented with a 6-month history of worsening left proptosis and painless ophthalmoplegia. Imaging revealed an extensive intraconal and extraconal tumor extending to the level of the optic foramen, as well as the scalp, cheek, and the nasal bridge. Incisional biopsy was consistent with lacrimal gland adenocarcinoma. The patient underwent a left orbital exenteration followed by immunotherapy with pembrolizumab. The treatment was stopped prematurely after 5 cycles due to development of autoimmune colitis. Four months later, the patient developed new contralateral disease in the right orbit and an incisional biopsy again showed lacrimal gland adenocarcinoma. Following the incisional biopsy, no further treatment was administered, but over the ensuing 6 months, there was dramatic spontaneous regression of the tumor both clinically and radiographically. At 28 months, the patient is still alive with relatively stable disease.