UC San Diego

Kaposiform lymphangiomatosis (KLA) is a rare disorder characterized by lymphatic anomalies—primarily intrathoracic—and systemic manifestations including coagulopathy, respiratory symptoms, and pleural and/or pericardial effusions. We present the case of a 12-year-old male with KLA complicated by Kasabach–Merritt phenomenon, recurrent pericardial effusions, multifocal bone lesions, and pneumococcal meningitis. Diagnosis was suspected based upon imaging that revealed abnormal pulmonary and mediastinal lymphatics, splenomegaly with low-attenuation lesions in the spleen, and multiple lytic bone lesions. A blood test (FoundationOne Liquid CDX) revealed an activating NRAS Q61R mutation that is frequently associated with KLA. The patient’s pericardial effusions and lytic bone lesions resolved, and Kasabach–Merritt phenomenon improved with combination therapy including sirolimus, zoledronic acid, prednisone, and trametinib.