Pagetoid variant of actinic keratosis with or without squamous cell carcinoma of sun‐exposed skin: a lesion simulating extramammary Paget's disease

Abstract

Actinic keratosis, particularly squamous cell carcinoma in situ of sun-exposed skin, may have histopathological and immunohistochemical features similar to extramammary Paget's disease and probably represents a variant of actinic keratosis. Awareness of the pagetoid variant of actinic keratosis arising in sun-exposed skin is helpful to avoid the over-diagnosis of extramammary Paget's disease.

An immunohistochemical comparison of cytokeratin 7, cytokeratin 15, cytokeratin 19, CAM 5.2, carcinoembryonic antigen, and nestin in differentiating porocarcinoma from squamous cell carcinoma

“…We observed CAM5.2 expression in 51% of porocarcinomas, comparable with 38% previously reported in a series of 8 porocarcinomas [36]. CAM5.2 has also been reported in up to 58% of cases of SCC [10,13].…”

“…A previous study has shown that CK7 labels 2 of 3 cases (67%) of porocarcinoma [14]. However, its expression can be seen in 13% to 27% of cases of invasive SCC cases (especially the poorly differentiated ones) and in cutaneous squamous cell carcinoma in-situ [15,16,36]. Similar to these findings, we found the expression of CK7 in 64% and 26% of our porocarcinoma and SCC cases, respectively [14,15].…”

The squamous variant of eccrine porocarcinoma: a clinicopathological study of 21 cases

“…Mai et al 21 refer to a pagetoid variant of actinic keratosis and the presence of divergent sweat gland differentiation has been reported in Bowen’s disease 22 – 24. There are, however, no reports thus far describing the presence of acrosyringial or poral differentiation in conventional cutaneous SCCs.…”

Sebaceous Carcinoma with Actinic Keratosis

“…On the other hand. Mai et al (4) reported that only 2 of 44 squamous cell carcinomas in situ without pagetoid spread of atypical keratinoeytes showed a moderate reactivity for CK-7 in atypical keratinocytes. So far there has been no reported ease of EMA expression in actinic kératoses.…”