Pyomyositis of the piriformis muscle in a juvenile.

The authors present a case of pyomyositis of the piriformis muscle. This case, the first in the English speaking literature of piriformis involvement in a juvenile, serves to illustrate the need for a high index of suspicion when treating children with symptoms related to impalpable pathology deep in the pelvis and the usefulness of MRI in early diagnosis and treatment before abscess formation. It also shows the potentially wide differential diagnosis in which the signs and symptoms may be misleading due to the close relationship of the pelvic muscles with the hip joint and adjacent viscera.