Localized thigh swelling mimicking a neoplastic process: involvement of coxsackie virus type A21

A 4-y-old girl was admitted because of a left leg limp with an isolated swollen upper thigh and normal muscle enzymes. A radioisotope scan showed increased uptake especially in the bone and soft tissue of the left thigh, while magnetic resonance imaging of that region demonstrated widespread oedema in striated muscle. On muscle biopsy perivascular infiltrates were demonstrated but muscle fibres were not shown to be affected. Sequence analysis of reverse transcription-polymerase chain reaction amplified fragments from the 5'-non-coding region of human enteroviruses identified a local strain of coxsackie virus A21 in the muscle. Clinical symptomatology subsided with oral steroids.

Local swelling mimicking a neoplasm may be related to infestation of coxsackie virus in muscle tissue.