Dermatologic Surgery
Cutaneous squamous cell carcinoma treated with Mohs micrographic surgery in Australia II. Perineural invasion

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Background

Perineural invasion (PNI) is an important histologic factor that plays a significant role in cutaneous tumors' aggressiveness.

Objectives

We sought to evaluate the incidence, features, and outcomes of cutaneous squamous cell carcinoma with PNI in patients treated with Mohs micrographic surgery (MMS).

Method

This prospective, multicenter, case series included all patients in Australia treated with MMS for squamous cell carcinoma with PNI who were monitored by the Skin and Cancer Foundation Australia between 1993 and 2002. The parameters recorded were patient demographics, duration of tumor, site, preoperative tumor size, recurrence before MMS, histologic subtypes, postoperative defect size, and recurrence at 5 years after MMS.

Results

Seventy patients were given a diagnosis of PNI. PNI was more common in men (77.1%) and in previously recurrent tumors (P = .04). The moderately and poorly differentiated histologic subtypes were more likely to be associated with PNI (P < .0001). Tumor sizes before excision, postoperative defect sizes, subclinical extension, and mean number of MMS levels were significantly larger in cases with PNI compared with cases without PNI (P < .0001, P < .0001, P = .002, and P < .0001, respectively). Most patients with PNI (52.9%) were treated with adjunctive radiotherapy. In all, 25 patients completed a 5-year follow-up post-MMS, and two of them (8.0%) were given a diagnosis of recurrence.

Conclusion

Although PNI is an uncommon feature of cutaneous squamous cell carcinoma, when present, it is associated with larger, more aggressive tumors, and the risk of recurrence is higher. This emphasizes the importance of tumor excision with margin control and long-term patient monitoring.

Section snippets

Methods

We conducted a prospective, noncomparative, multicenter, interventional case series of patients with cutaneous SCC treated with MMS in Australia and monitored by the SCFA between 1993 and 2002. All patients were treated by fellowship-trained MMS surgeons, using standard fresh-frozen MMS techniques, and the data were collected by the SCFA.

The criteria for selection were all cases of histologically diagnosed SCC with PNI treated with MMS. The following parameters were recorded: patient

Results

Data on PNI were available for 1177 patients who underwent MMS for cutaneous SCC (93.2%). PNI was diagnosed in 70 patients (5.95%); 54 were men (77.1%) and 16 were women (22.9%), with a mean age of 64 ± 15 years (median, 66 years; range, 35-96 years). There were 36 cases of PNI of the 772 cases of primary SCC (4.7%), and 34 cases of PNI of 491 cases with previously recurrent SCC (6.9%) (P = .04), comprising 51.4% and 48.6% of all PNI cases, respectively. Most tumors with PNI (91.4%) were present

Discussion

The perineural space is a cleavage plane between the nerve and the nerve sheath.10, 11 This plane extends from the small peripheral nerves, following their course to the subarachnoid space, and provides a pathway for cutaneous tumor spread to the central nervous system.12, 13 This mode of spread is a significant factor that contributes to the morbidity and mortality from cutaneous SCC.

In one of the first reports on PNI in skin tumors, Mohs and Lathrop5 reported 807 cases of SCC treated with

References (22)

  • J. Cruveilhier

    Maladies des nerfs

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    Funding sources: None.

    Conflicts of interest: None identified

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