Clinical History.—An 8-year-old boy was admitted to the hospital with pain in the left distal thigh. Three weeks prior to admission, he had fallen out of a grocery cart and landed on his outstretched hands and knees. The pain in the distal thigh has been present since that time, and he has had a persistent limp. The pain was characterized as dull, vague, and mild. The patient also noted a bump in the distal thigh area that was soft to touch and slightly tender.
There was a not well-substantiated history of weight loss. The remainder of the history was noncontributory.
Physical Examination.—He was a well-developed, well-nourished boy in no distress. The eyes, ears, nose, and throat were normal. The chest was clear to auscultation and percussion. The cardiac rhythm was regular and no murmurs were heard. The abdomen was soft and no organomegaly was palpated. There was swelling