Eruptive postoperative squamous cell carcinomas exhibiting a pathergy-like reaction around surgical wound sites

The isomorphic response of Koebner and the pathergy skin reaction have not classically been associated with neoplastic processes such as cutaneous squamous cell carcinoma (SCC).

We report 5 patients who developed postoperative eruptive SCCs within and around the healed or healing sites of excised nonmelanoma skin cancers. The original cancers were all excised with histologically tumor-free margins and the subsequent eruptive SCCs were sometimes multiple.

We performed follow-up examinations of patient's wounds after the treatment of skin cancer with Mohs micrographic surgery. Keratotic nodules that developed acutely in the margins of healing wound sites of these patients were examined histologically by a single dermatopathologist.

The tumors presented as rapidly growing keratotic nodules within the sites of previously excised cancers. The mean time of clinical appearance was approximately 6 weeks and histologic examination of the nodules demonstrated well-differentiated SCC.

This study is limited by its relatively small number of cases.

Acutely eruptive SCC is a rare but significant postoperative complication of skin cancer surgery. Furthermore, this case series suggests that some individuals appear to be predisposed to this recurrent, pathergy-like reaction involving SCC.