Large Nonosseous Preaxial Polydactyly: Unique Case With Vascular Proliferation and Subepidermal Bullae.

Preaxial polydactyly (PPD) is characterized by a supernumerary finger or duplication of digital parts on the radial aspect of the thumb. There is a wide phenotypic variety among presentations of PPD. Numerous classification systems have been created to categorize these phenotypes. Here, we present a rare case of PPD that does not fit into any of the known classification systems. The patient was born with a large nonosseous PPD. The patient was treated successfully with sharp excision, and pathology confirmed the diagnosis of a soft-tissue-only supernumerary digit containing unique features of vascular proliferation and subepidermal bullae. While this case is the only one of its kind, similar cases have been reported in the recent literature. Therefore, we should consider implementing this PPD phenotype into a classification system to guide patient counseling, clinical decision-making, and management.