Perineural invasion

[3] In prostate cancer, PNI in needle biopsies is poor prognosticator;[2] however, in prostatectomy specimens it is unclear whether it carries a worse prognosis.

Tumor cells secrete CCL2 and CSF-1 to accumulate endoneurial macrophages and, at the same time, release factors that stimulate perineural invasion.

Although adenoid cystic carcinoma accounts for only 1-3% of head and neck tumors, it has the highest relative incidence of PNI.

PNI is also commonly found in patients with salivary duct carcinomas, polymorphous low-grade adenocarcinomas, cutaneous malignancies, desmoplastic melanomas, myelomas, lymphomas, and leukemias.

PNS recurrence is rarely resectable, and repeated irradiation has greater toxic side effects and fewer benefits compared with initial early treatment.