Acantholytic squamous cell carcinoma arising in actinic keratoacanthoma: Two cases with E-cadherin expression supporting a potentially different prognosis

Abstract

Among crateriform squamous proliferation, keratoacanthoma is considered as a squamous cell carcinoma or as a non-malignant, self-healing lesion that frequently becomes malignant. To date, published cases of neoplasms originating from keratoacanthoma are always conventional squamous cell carcinomas. Acantholytic squamous cell carcinoma arising in keratoacanthomas has not been previously reported. We present two crater-shaped nodular lesions on the face of elderly patients with clinical and histopathological features of keratoacanthoma with transformation areas to acantholytic squamous cell carcinoma. In the immunohistochemical study, Ki-67 and p63 immunostaining supports the diagnosis of acantholytic squamous cell carcinoma ex-keratoacanthoma. We suggest that E-cadherin expression and vimentin negativity could probably be related with less aggressive behaviour and a better prognosis.