Multiplying Brown Spots.

PURPOSE: Bilateral diffuse uveal melanocytic proliferation (BDUMP) is a paraneoplastic syndrome affecting the eye that is a sign of poor prognosis of underlying malignancy.This is the first documented case to show serial and sustained improvement of BDUMP following immunotherapy in the setting of primary non-small cell carcinoma of the lung. OBSERVATIONS: A 65-year-old man reported a gradual decrease in vision and floaters in the right eye after cataract surgery. Fundus examination demonstrated diffuse multiple brown subretinal lesions bilaterally. Next generation sequencing of melanocytic tissue of the patient described in this case revealed a specific RB1 c.411A>T (p.Glu137Asp) variant with an allele frequency of 44.8%, consistent with heterozygosity. Plasma samples from the patient and a control patient with no history of cancer and/or paraneoplastic syndrome were cultured with neonatal melanocytes, which revealed a greater than 180% increase in proliferation of normal neonatal melanocytes compared to the control. Pembrolizumab therapy was initiated which resulted in shrinkage and stabilization of the lesions documented in serial diagnostic testing. CONCLUSIONS: In conclusion, we report a cytologically and serologically confirmed case of BDUMP in a patient with a primary non-small cell carcinoma of the lung. Next generation sequencing of melanocytic tissue of the patient described in this case revealed a specific RB1c.411A>T (p.Glu137Asp) variant with an allele frequency of 44.8%, consistent with heterozygosity. Furthermore, we show documented serial improvement in the patient's ocular and systemic disease with treatment. This case as one of the longest surviving confirmed cases of a patient with BDUMP.