Conjunctival CD20-Positive B-Cell Lymphoma with High-Grade Cytological Features in a Young Adult Mimicking a Benign Conjunctival Lesion: A Case Report

Abstract

Aims: To report an unusual case of conjunctival CD20-positive B-cell lymphoma with high-grade cytological features in a young adult that initially mimicked a benign conjunctival lesion, and to emphasise the diagnostic limitations of a restricted immunohistochemical panel. Presentation of Case: A 20-year-old man with no relevant medical history presented with persistent photophobia, redness, pruritus and discomfort in the left eye for several months; the exact duration of symptoms and details of previous topical medications were not fully documented in the submitted clinical record. Best-corrected visual acuity was 10/10 in both eyes. Slit-lamp examination showed a localised, elevated lesion of the left inferior bulbar conjunctiva, clinically suggestive of a benign lesion such as pinguecula, without abnormalities of the cornea, anterior chamber, fundus or contralateral eye. Because of the persistent atypical course, an excisional biopsy was performed. Histopathological examination showed diffuse subepithelial infiltration by atypical large lymphoid cells with irregular nuclei, prominent nucleoli and numerous mitoses. Immunohistochemistry showed LCA/CD45 and CD20 positivity, CD3 staining limited to reactive T cells, negativity for pan-cytokeratin and CD99, and a Ki-67 index of 67%. Cervico-thoraco-abdomino-pelvic computed tomography and haematological assessment showed no documented systemic involvement, supporting Ann Arbor stage IE and clinically probable AJCC ocular adnexal lymphoma stage cT1N0M0; however, dedicated orbital imaging, PET/CT and bone marrow examination were not documented. Discussion: The available findings establish a haematolymphoid B-cell neoplasm but do not permit definitive WHO/ICC subclassification. An extended haematopathology panel and molecular studies are required to distinguish extranodal marginal zone lymphoma, follicular lymphoma, diffuse large B-cell lymphoma, high-grade B-cell lymphoma, EBV-associated disease and other mature B-cell neoplasms. The patient was referred for multidisciplinary oncological management; external beam radiotherapy was planned, but treatment delivery, response, toxicity and long-term outcome were unavailable at the time of manuscript preparation. Conclusion: Persistent or atypical conjunctival lesions in young adults should not be assumed to be benign. Early biopsy, immunohistochemistry, careful lymphoma subclassification, systemic staging and multidisciplinary management are essential, while diagnostic uncertainty must be explicitly reported when ancillary data are incomplete.