Clinical History.—A 12-year-old boy was admitted to the hospital complaining of backache and generalized bone pain of six months' duration. For the past two months, he was unable to sit or stand due to the pain.
Physical Examination.—The patient appeared pale, and a dorsal kyphosis was present. The examination of the heart and lungs was normal. A smooth, nontender liver was palpable but there was no splenomegaly or lymphadenopathy. Marked skeletal tenderness was elicited. All other functions were normal.
The hemoglobin value was 10.5 gm/100 ml; the leukocyte count was 10,800/cm, with 65% neutrophils, 30% lymphocytes, and 5% eosinophils. There was mild anisocytosis, poikilocytosis with few microcytes, and an occasional nucleated red blood cell seen in the peripheral blood smear. No immature leukocytes were identified. The serum calcium value was 10.5 mg/100 ml, and inorganic phosphorus level was 5.3 mg/100 ml. Because of the generalized bone