Atypical cytomegalovirus retinitis in an immunocompetent individual with diffuse large B-cell lymphoma posing a diagnostic enigma

Cytomegalovirus (CMV) retinitis is a vision-threatening condition seen with CD4+ count below 50/μL. In the presence of systemic lymphoma, CMV retinitis may pose a diagnostic dilemma due to similar clinical features with intraocular lymphoma. We, hereby, report a rare case of bilateral CMV retinitis in a patient with normal CD4+ counts and a past history of diffuse large B-cell lymphoma (DLBCL). A 51-year-old male presented with sudden-onset painless diminution of vision in the right eye (RE) for a 2-week duration. He had a past history of DLBCL and had been treated with chemotherapy. On examination, his best-corrected visual acuity was perception of light in RE and 20/20 in the left eye (LE). RE fundus examination showed yellowish-white deep retinal lesions with scanty superficial retinal hemorrhages and perivascular exudates. LE fundus examination showed only one focal area of yellowish-white deep retinal lesions along the inferotemporal arcade. A provisional diagnosis of bilateral intraocular lymphoma was made based on the past history of systemic lymphoma. RE vitreous tap was done, and intravitreal injection of methotrexate was given. Vitreous sample revealed CMV DNA on polymerase chain reaction but no evidence of malignant cells on cytology. CD4 count was 393 cells/μl. The patient was subsequently treated with intravenous ganciclovir and oral valganciclovir for bilateral CMV retinitis. This case report highlights the importance of vitreous sample analysis in patients of systemic lymphoma presenting with atypical retinal necrotic lesions to establish an accurate diagnosis and to differentiate between closely mimicking lesions of intraocular lymphoma and viral retinitis.