Well-circumscribed intramuscular lipoma of the sternocleidomastoid muscle.

Intramuscular lipomas are unusual benign mesenchymal tumours, which infiltrate the skeletal muscle, and are exceedingly rare in the head and neck region. They commonly infiltrate the skeletal muscle fibres from which they arise and are rarely well circumscribed. We present the only documented case of well-circumscribed intramuscular lipoma arising from the sternocleidomastoid muscle. Although the recurrence is commoner in the infiltrative variety the surgeon should be aware that differentiation between infiltrative and well circumscribed is based on histological diagnosis, and hence wide excision in all cases of intramuscular lipomas is essential.