Chronic streptococcal pneumonia presenting as a chest wall mass: An unusual case of malakoplakia

Introduction

Malakoplakia is a rare disorder of defective macrophage bactericidal function associated with gram-negative organisms. Pulmonary involvement is uncommon, and association with Streptococcus pneumoniae is exceedingly rare, often mimicking thoracic malignancy. Case: 72-year-old man with a 50-pack-year smoking history and chronic alcohol use presented with cough, dyspnea, fever, weight loss and a tender left chest wall mass. Computed tomography demonstrated a 10.9 × 6.2 cm mass traversing multiple tissue planes with mediastinal lymphadenopathy raising concern for malignancy. Cultures grew Streptococcus pneumoniae. Lung biopsy revealed Periodic Acid-Schiff positive macrophages with chronic inflammatory infiltrate and histiocytes without evidence of malignancy, confirming pulmonary malakoplakia. He received ceftriaxone followed by amoxicillin-clavulanate alongside surgical debridement, achieving clinical improvement. Re-biopsy confirmed the absence of malignancy.