Bilateral sternocleidomastoid tumor of infancy.

The sternocleidomastoid tumor of infancy (STOI), also known as fibromatosis colli, presents as a firm well circumscribed mass within the sternocleidomastoid muscle (SCM) in infants of 1-8 weeks of age. Some of these lesions are associated with torticollis, facial and cranial asymmetry. Incidence of STOI is approximately 0.4% of live births and usually 90% of the patients will have a good prognosis if therapy is initiated and continued for the appropriate period of time. This paper presents two cases of bilateral involvement of STOI, which is very rare. The bilateral nature of the masses added to the uncertainty of the clinical diagnosis and the unusual features of these cases are discussed.