Acantholytic invasive squamous cell carcinoma: tumor diameter, invasion depth, grade of differentiation, surgical margins, perineural invasion, recurrence and death rate.

BACKGROUND: Squamous cell carcinoma (SCC) may present with or without the feature of acantholysis.

METHODS: Investigate invasive acantholytic SCC by microscopic maximum tumor surface diameter, depth of invasion, grade of differentiation, perineural invasion (PNI) and percentage of acantholysis. Assess recurrence following excision.

RESULTS: A total of 1658 consecutive invasive SCC cases were examined, comprising 4.9% acantholytic SCC. Median tumor microscopic maximum diameter was 8 mm for acantholytic SCC and 7.3 mm for non-acantholytic SCC. Median tumor invasion depth was 1.0 mm for acantholytic SCC and 1.5 mm for non-acantholytic SCC. Well, moderate and poor differentiation were not significantly different between acantholytic SCC and non-acantholytic SCC. One PNI case was found in 82 acantholytic SCC cases. A total of 77 acantholytic SCC cases were followed up over a median 25 months finding histologic proven recurrence at three acantholytic SCC excision sites.

CONCLUSIONS: Acantholytic SCC were more likely to be located on head sites with less median depth than non-acantholytic SCC. Increasing percentage of acantholysis within acantholytic SCC was not associated with a shift towards poor differentiation. Histologic margins of 1.2 mm may adequately excise small acantholytic SCC. No recorded deaths, low PNI and low recurrence rates suggests acantholytic SCC is low-risk.