Challenges in Diagnosing Pleural Thickening: Primary Pleural Follicular Lymphoma

This is the case of a 66-year-old male with a medical history of HIV infection on combination antiretroviral therapy (cART) who presented to the hospital with gradually worsening chronic right-sided chest and abdominal pain over the past three months. Computed tomography (CT) with contrast showed new mass-like pleural thickening in the right lower lobe posteriorly with an associated small loculated right pleural effusion. A core needle pleural biopsy was performed, and the results were consistent with primary pleural malignant lymphoma. Histopathological and immunohistochemical examinations revealed CD10-positive, low-grade B-cell lymphoma. This case is considered a rare occurrence of primary malignant lymphoma developing in the pleura.