CRA4 A SILENT INTRUDER: PRIMARY PULMONARY FOLLICULAR LYMPHOMA MIMICKING INFECTIOUS LUNG DISEASE IN A PATIENT WITH AUTOIMMUNE COMORBIDITIES

Hemalatha Munusamy 1, Rozanah Bt Abd Rahman 1, Lim SY 1, Bazli Bin Bahar 1
1 Department of Respiratory medicine, Hospital Sultanah Aminah, Johor Bahru, Malaysia

Primary pulmonary follicular lymphoma (PPFL) is an exceptionally rare subtype of non-Hodgkin lymphoma that arises in the lung without extrapulmonary or nodal involvement at diagnosis. Its presentation often mimics other more common pulmonary conditions, leading to delayed diagnosis. We report the case of a 64-year-old female with a history of diabetes mellitus, hypertension, and cutaneous systemic lupus erythematosus (SLE), who presented with a one-month history of persistent cough. She denied constitutional symptoms such as fever, weight loss, or night sweats. Physical examination and laboratory investigations, including full blood count, liver, and renal function tests, were unremarkable. Chest X-ray revealed multiple bilateral nodular opacities. Initial microbiological and cytological investigations, including sputum and BAL for Mycobacterium tuberculosis, were negative. A CT thorax confirmed multiple bilateral lung nodules with irregular margins. Bronchoscopy and initial CT-guided biopsy were inconclusive, showing only heterogeneous lymphocytic infiltrates without malignancy. Due to persistent symptoms and radiologic findings, a repeat CT-guided biopsy was performed. Histopathological analysis demonstrated malignant lymphoid cells expressing CD20, CD10, Bcl2, Pax5, and Leucocyte Common Antigen, with scattered Bcl6 positivity, consistent with a diagnosis of primary pulmonary follicular lymphoma, grade 2. This case highlights the diagnostic challenge of PPFL, particularly in patients with underlying autoimmune disease and nonspecific symptoms. Persistent radiologic abnormalities and multidisciplinary collaboration were key in achieving a definitive diagnosis. Awareness of PPFL as a differential diagnosis in chronic, unexplained pulmonary nodules is essential for timely management.