Rhabdomyosarcoma presenting with diffuse bone marrow involvement, hypercalcemia and renal failure

Rhabdomyosarcoma and other small round-cell neoplasms of infancy and childhood frequently involve the bone marrow. An unusual clinical presentation of diffuse bone marrow involvement as the sole manifestation of the disease represents a difficult diagnostic challenge. We report the case of an 18-year-old boy presenting with lower back pain, sternum tenderness, anemia, thrombocytopenia, leukoerythroblastic blood film, hypercalcemia, and renal failure. No solid tumor was found. A diagnosis of rhabdomyoblastic bone marrow metastatic involvement was initially suggested by the morphological picture, and later confirmed by the ultrastructural findings. Hypercalcemia and renal failure were controlled, initially, with furosemide and calcitonin. The patient was treated with intensive chemotherapy, including vincristine, actinomycin D, cyclophosphamide, and doxorubicin. A remission was achieved, lasting 5 months until relapse.