Isolated Malignant Pleural Effusion in a Child: Unusual Presentation of Acute Leukemia.

Pleural effusion in the pediatric population is an abnormal pathology characterized by the accumulation of fluids between the parietal and visceral pleura. The etiology of this excessive fluid accumulation can be attributed to both infectious and non-infectious factors. Notably, Streptococcus pneumoniae stands out as the predominant infectious agent responsible for this condition. Non-infectious causative factors encompass hematolymphoid malignancies, congestive heart failure, hemothorax, hypoalbuminemia, and iatrogenic causes. Among the hematolymphoid malignancies, lymphoma emerges as the most prevalent malignancy associated with pleural effusion. It is followed by T-cell lymphoblastic leukemia, germ cell tumor, neurogenic tumor, chest wall and pulmonary malignancy, carcinoid tumor, pleuro-pulmonary blastoma, and Askin's tumor, among others. Malignant pleural effusion is predominantly linked to T-cell lymphoblastic malignancies. In the context of acute lymphoblastic leukemia (ALL), cases where T-cell presentation is accompanied by leukemic pleural effusion are commonly associated with either a mediastinal mass or significant lymphadenopathy. Here, we describe a case of a four-year-old male child who exhibited a brief history of febrile illness. Notably, this case was characterized by isolated pleural effusion, devoid of any mediastinal mass or lymphadenopathy. Pathological investigations of pleural fluid analysis revealed the presence of malignant cells, facilitating an expedited diagnosis.