A 9-year-old boy, born of third-degree consanguinity, presented with a hard left scapular swelling that had been persistent for 6 months. There was no history of fever, trauma, or weight loss. There was no pain, redness, or discharge. This mass was excised but recurred over the next 6 months (left panel of Figure 1). A similar swelling had been excised from the left knee 1 year before presentation, but had recurred over 6 months. Family history was negative for similar lesions. Development was normal for age and he had no other medical problems.