Table 1. Main differences between EMPD, Bowen disease and melanoma-in-situ. Immunohistochemical markers in bold are part of recommended panel for the characterization of these lesions.



Common sites

Dermoscopy findings

Histopathological features

Immunohistochemical stains

Extra-mammary Pagets disease

Apocrine-rich areas of perineum, groin, genitalia and axillae.

Equivocal pigmentation [32], but may have features of MIS

Mucin-rich clear plump cells in the epidermis, may have signet ring appearance, and some may be in clusters, glandular or tubular differentiation. Rarely Paget cells may contain melanin pigment.

CK7, CK20, CAM5.2, CEA, EMA

Squamous cell carcinoma-in-situ

Sun-exposed sites of the face, extremities, also frequently in groin and genitalia

Linear brown/grey dots

Coiled vessels [33]

Full-thickness atypia of epidermis with loss of polarity, with possible extension along follicular and adnexal structures, occasionally may also contain melanin pigment

p63, high molecular weight cytokeratin eg. 34βE12

Melanoma-in-situ (MIS)

Typically in sun exposed sites

Irregular pigment network, blue-white veil and blue-grey areas

Pigmented atypical melanocytes with Pagetoid spread, fine melanin granules and pleomorphic naevus cells in basal layer of epidermis

S100, HMB45