Perineural invasion in dSCC
The desmoplastic type of squamous cell carcinoma (dSCC) is one that has fine branches surrounded by a desmoplastic stroma or connective tissue. dSCC accounts for just under 10% of all cutaneous SCC and is clinically indistinguishable so only diagnosed on histological examination.
Perineurial invasion (PNI) of the cancer in the space surrounding a nerve only occurs in dSCC which represents about 15% of all SCC. Patients with dSCC and PNI have significantly more lymph node metastases, local recurrences and tumour specific mortality than non-desmoplastic SCC or dSCC without PNI.
Apart from desmoplasia and PNI, significant independent factors for SCC recurrence include poor differentiation, thickness >6mm, tumour horizontal size >20mm and immunosuppression.