Infiltrating lipoma: a cause of monomelic hypertrophy

Muscle biopsy and computerized tomography indicated that unilateral enlargement of the gastrocnemius muscle in a 12-year-old girl was the result of an infiltrating lipoma. This rare condition may cause diagnostic confusion before EMG and muscle biopsy studies are performed, but it can be readily distinguished from other causes of unilateral muscle enlargement using these methods.