Cutaneous nodular fasciitis with genetic analysis: a case series.

Nodular fasciitis is a benign self-limited myofibroblastic neoplasm, which usually involves the upper extremities and trunk of young patients. These tumors have been shown to harbor a translocation involving the MYH9 and USP6 genes, leading to overexpression of the latter. We report seven cases of nodular fasciitis with cutaneous presentations. All cases involved the dermis, with six involving the superficial subcutis, and one auricular tumor extending into cartilage. All cases showed USP6 rearrangement by fluorescence in situ hybridization; in two of three cases, the characteristic MYH9-USP6 fusion was shown by RT-PCR. All patients underwent conservative resection. Nodular fasciitis is an uncommon mesenchymal neoplasm that can occasionally present in superficial locations and is sometimes mistaken for a malignant process. Molecular testing can be useful to distinguish this entity from other cutaneous spindle cell tumors.