Simultaneous Involvement of Lung and Bone Tissues in Pediatric Anaplastic Large Cell Lymphoma ALK+: A Case Report.

Anaplastic large cell lymphoma (ALCL) is a subtype of non-Hodgkin lymphoma characterized by the presence of CD30+ lymphocytes. While nodal involvement is common, extranodal manifestations are less frequent, with the skin being the most commonly affected organ, followed by the lungs, bones, and liver. We present the case of a 10-year-old girl who experienced a 4-month history of intermittent fever, abdominal pain, significant weight loss, and debilitating lumbar pain that restricted her mobility. Computed tomography scans performed at a national pediatric reference center in Lima, Peru, revealed osteolytic lesions primarily affecting the D12 vertebra. During hospitalization, the patient developed dyspnea and chest pain due to bilateral pleural effusions. The suspected diagnosis of ALK + ALCL was confirmed through lymph node biopsy, alongside the identification of malignant CD30+ cells in pleural fluid via flow cytometry. Following the initiation of chemotherapy, the patient experienced a complete resolution of symptoms. This case highlights the atypical simultaneous extranodal involvement of both bone and lung in pediatric ALK + ALCL, a manifestation rarely documented in the existing literature. Furthermore, it demonstrates the potential value of pleural fluid flow cytometry as a complementary diagnostic approach in ALCL, particularly when tissue biopsy is limited or not feasible. The insights provided in this report aim to assist healthcare professionals in diagnosing and managing similar cases encountered in clinical practice.