Reexcision perineural invasion: a mimic of malignancy

The presence of epithelium in the perineural space is typically associated with invasion by malignant tumors. In this report, bland-appearing epithelium was identified in the perineural space associated with a dermal reparative reaction after removal of a melanoma in 4 patients. After exclusion of possible squamous cell carcinoma and immunohistochemistry, a diagnosis of reexcision perineural invasion was made. The report illustrates the features of this uncommon and little recognized entity which has not been previously reported in the dermatology or dermatopathology literature. A lack of appreciation of the condition may lead to a misdiagnosis of malignancy, especially squamous cell carcinoma. The cases also highlight the need for good clinical correlation when examining reexcision specimens. There may be increased recognition of reexcision perineural invasion with the rise in reexcisions that are being performed, with some surgeons reexcising Spitz nevi and dysplastic nevi, for example.