Reparative perineural hyperplasia: a series of 10 cases

Healing wounds are commonly examined by pathologists at the time of reexcision of skin tumors to ensure complete removal of the lesion. In addition to searching for residual tumor, possible perineural invasion must be assessed. During routine examination of reexcision specimens, 10 cases of prominent perineural proliferation were seen associated with fine nerves in the mid or deep dermis. The process showed a concentric cellular proliferation with no, or only limited, nuclear hyperchromasia or pleomorphism. In a number of cases, immunohistochemistry was essential to exclude the possibility of malignant perineural invasion or other mimics of this process such as reexcision perineural invasion. The term reparative perineural hyperplasia is proposed for this entity, which is important for pathologists to be aware of to avoid misdiagnosis.