Patient is a 14-year-old female with Niemann Pick disease type C manifested primarily with seizures. This subcategory is a result of defective intracellular processing and transporting of low-density lipoprotein-derived cholesterol. She presented with acute abdominal pain. The bone marrow aspirate and biopsy were obtained following splenectomy for splenic torsion. The marrow was hypercellular with marked hyperplasia of macrophages (histiocytes). The image shown illustrates the characteristic foamy cytoplasm of the histocytes in this disease.