It was interpreted as fibrous hamartoma of infancy with benign features.
Fibrous hamartoma of infancy was first described by Reye in 1954 and later coined its current name 'fibrous hamartoma of infancy' by Enzinger in 1965.
Subdermal fibrous hamartoma of infancy: pathology of 40 cases and differential diagnosis.
Other cutaneous and subcutaneous lesions that are considered in the differential diagnosis include leiomyoma, hemangiopericytoma, fibrous hamartoma of infancy
, cutaneous inflammatory pseudotumor, desmoid tumor, nodular fasciitis, plexiform fibrohistioeytic tumor, neurofibroma, and dermatomyofibroma.