PLASMA CIRCULATING TUMOR DNA TO ASSIST IN THE DIAGNOSIS OF UNKNOWN PRIMARY MALIGNANCY UNDERLYING CHOROIDAL METASTASES.

Purpose: Management of suspected choroidal metastases requires diagnostic imaging and an invasive, sometimes intraocular, biopsy to determine the primary malignancy. This multistep process takes time, which may affect morbidity and mortality.

Methods: This was a retrospective review of one case.

Results: A 56-year-old woman presented with bilateral amelanotic choroidal masses suspicious for metastases of unknown origin. Plasma circulating tumor DNA revealed EGFR , PTEN , and SMAD4 , a profile consistent with non-small-cell lung cancer. Subsequent radiographic imaging and scapular biopsy revealed lung adenocarcinoma and genetic profile concordant with the liquid biopsy. The patient was started on EGFR inhibitor, osimertinib, with measurable systemic and ocular response.

Conclusion: Plasma circulating tumor DNA revealed the genetic profile of the primary malignancy underlying choroidal metastases of unknown origin, aiding in the prompt diagnosis and detecting the driver mutation that guided management with targeted therapy.