Fibromatosis presenting as a sacrococcygeal mass

Most children older than a year who present with a sacrococcygeal mass have a malignant tumor. We describe an 8-year-old child with of a sacrococcygeal soft tissue mass that was completely resected with histologic findings consistent with fibromatosis. Fibromatosis is a deep-seated, musculoaponeurotic, borderline tumor that is rare in childhood and has a high incidence of local recurrence even after margin-free resection. We review and discuss management strategies for treatment of fibromatosis in children. This case represents the first report of fibromatosis presenting as a sacrococcygeal mass.