Search

Pigmented epidermotropic breast cancer metastases are a rarity, often clinically misdiagnosed as melanocytic lesions. Histopathologically, they show a dermal proliferation of neoplastic metastatic cells that extend to the overlying epidermis in a pattern identical to that seen in primary Paget disease (PD). Differential diagnosis should be established with entities with a similar presentation, such as pigmented mammary PD and malignant melanoma. Immunohistochemistry may be useful for this purpose. We present a new case of pigmented epidermotropic breast cancer metastases with a particularly unusual feature: the absence of dermal infiltration by neoplastic cells, thus considered as pure epidermotropic metastatic involvement. [ABSTRACT FROM AUTHOR]

Microcystic adnexal carcinoma (MAC) is a low‐grade adnexal carcinoma with controversial lines of differentiation. We present here an example of MAC showing histopathologic findings of germinative follicular differentiation in the form of solid aggregates of trichoblastoma intermingled with neoplastic aggregates of MAC. Immunohistochemical findings, showing positivity for PHLDA1 and negativity for BerEp4 in neoplastic aggregates of trichoblastoma, also supported a germinative follicular differentiation. Follicular differentiation in MAC supports an apocrine line of differentiation for this neoplasm. [ABSTRACT FROM AUTHOR]

Toker cells (TCs) are sometimes present in the nipple epidermis as oval cells with pale cytoplasm and roundish nuclei. In most cases, TCs may be easily distinguished from cancerous cells of Paget disease of the nipple (PCs). Especially in TC hyperplasia, in which mild‐to‐moderate atypia may be present, it may be challenging to distinguish between TCs and PCs. The combination of chronic inflammatory changes in the nipple, in the context of Zuska disease, and TC hyperplasia, may easily lead to an erroneous diagnosis of mammary Paget disease. [ABSTRACT FROM AUTHOR]