Acantholytic squamous cell carcinoma is usually associated with hair follicles, not acantholytic actinic keratosis, and is not "high risk'': Diagnosis, management, and clinical outcomes in a series of 115 cases

Background: Acantholytic squamous cell carcinoma (aSCC) is regarded as a high-risk variant of cutaneous squamous cell carcinoma (SCC). Acantholytic actinic keratosis (aAK) has been regarded as a precursor risk factor for aSCC. However, supporting evidence is limited. Objective: We sought to document clinical features, histologic features, management, and outcomes in a series of aSCC cases. Methods: Definitions of aSCC, aAK, and aSCC arising in association with aAK were applied to a consecutive series of aSCC cases. Clinical characteristics and outcomes were obtained from electronic medical records. Results: Of 115 aSCC cases (103 patients, mean age 71.8 years), actinic keratosis was present in 23% (27/115) but only 7.8% (9/115) exhibited associated aAK. Ten cases (10/115, 9%) fulfilled strict histologic criteria for follicular SCC as previously defined, but 50 of 115 (43%) of our aSCC cases exhibited predominant involvement of follicular epithelium rather than epidermis. Clinical outcome (median follow-up, 36 months) was available in 106 of 115 (92%). One patient experienced regional extension (parotid), and 1 patient experienced a local recurrence (nose). No disease-related metastases or deaths were documented. Limitations: This was a single-institution retrospective study from the United States. Conclusions: The presence of acantholysis in cutaneous SCC does not specifically confer aggressive behavior, a finding that may inform clinical practice guidelines.