An aggressive nodular fasciitis lesion protruding from the palm (USP6 gene fusion helps differentiate from sarcomas): A case report.

Nodular fasciitis is a mesenchymal lesion, which has been viewed as a reactive process. The MYH9-USP6 fusion gene was recently detected in nodular fasciitis, and nodular fasciitis is now considered to be a self-limiting neoplastic process. Recently, a case of nodular fasciitis that recurred a number of times and metastasized to soft tissues was reported, and the features of aggressive cases of nodular fasciitis are currently under investigation. Here, a case of locally aggressive nodular fasciitis is presented, in which the lesion grew rapidly and caused ulnar nerve palsy. The lesion was locally controlled via marginal excision, and no metastasis was identified at 24 months post-operation. Histologically, the lesion was consistent with nodular fasciitis, and the detection of the MYH9-USP6 fusion gene supported the diagnosis. Although most nodular fasciitis lesions are benign, some may be locally aggressive or even metastasize. In the case outlined in the present study, marginal excision was sufficient to locally control the lesion.