Congenital desmoid tumor of the scalp: a histologically benign lesion with aggressive clinical behavior.

Desmoid tumors are uncommon benign neoplasms of fibroblastic origin, frequently presenting in the abdomen or abdominal wall of adults. This tumor is well known to general surgeons and pathologists, but it has rarely been reported in the neurosurgical literature. We describe a neonate who presented with a right temporal subscalp tumor at birth. In spite of initial apparent total removal, the tumor recurred twice. We discuss the diagnostic pitfalls encountered in assessing this tumor and the difficulties in distinguishing, in the excised specimens, between desmoid and reactive fibrosis. We suggest that desmoid tumor should be considered in the differential diagnosis of scalp and calvarial masses in children. Complete excision is required to prevent recurrences, and sometimes a multidisciplinary team is needed to secure margin-free resection.