Primary central nervous system lymphoma presenting as a single choroidal lesion mimicking metastasis: A case report

BACKGROUND: Primary choroidal lymphoma is usually an indolent B-cell lymphoma and rarely progresses to extraocular sites. Herein, we report a case of primary choroidal lymphoma diagnosed as diffuse large B-cell lymphoma (DLBL), which progressed to the brain parenchyma after 4 mo. CASE SUMMARY: A 78-year-old man presented with diminution of vision in his right eye. A choroidal lesion suspected of metastatic lesion was observed in the right eye by ophthalmologic examination. To discover the primary tumor, imaging investigations were performed but no malignant lesion was detected. After 4 mo, the patient returned to the clinic presenting with neurological symptoms. Brain magnetic resonance imaging revealed an abnormal contrast-enhancing mass in the left cerebellum. A stereotactic biopsy was performed, and DLBL was confirmed. The patient received the high dose methotrexate-based chemotherapy and he achieved complete remission. CONCLUSION: Primary choroidal lymphoma is usually known to have a benign clinical course without systemic involvement. We present a rare case of primary choroidal lymphoma diagnosed as DLBL that progressed to the brain parenchyma within months.