Soft tissue, Fibrous hamartoma of infancy

Fibrous hamartoma of infancy is a benign hamartomatous mass of children under 3 years old occurring on trunk and limbs. It presents as a painless subcutaneous mass. Histologically, it has three components: fat, fibrous tissue, and immature mesenchyme. The fat is mature and the fibrocollagenous spindle cell septae have immature stellate cells (immature mesenchyme). May show extensive sclerosis in older children. Treated by local excision. May recur locally. Immunohistochemistry: vimentin positive, desmin negative, some cells may stain with CD34.