Abstract
Macrophage activation syndrome (MAS) is a rare and potentially fatal condition. Also known as macrophage activation syndrome, its diagnosis is based on the presence of at least five clinical and biological criteria. Bone marrow examination helps confirm the diagnosis by demonstrating the presence of numerous activated macrophages with multiple hemophagocytosis images. Through the case of an immunocompromised patient followed for chronic lymphocytic leukemia (CLL), we emphasize the difficulty of diagnosing MAS and the need to screen for underlying tuberculosis, which may be masked by manifestations of the lymphoproliferative syndrome. The diagnosis of MAS was established based on clinical, biological, and cytological abnormalities, with pleural tuberculosis identified as the triggering factor. This case emphasizes the need to consider opportunistic infections and to maintain a high index of suspicion in immunocompromised patients, illustrating an unusual clinical and epidemiological triad. Keywords: macrophage activation syndrome; chronic lymphocytic leukemia; pleural tuberculosis; diagnosis; treatment.