Pigmented mammary Paget disease positive for melanocytic markers

Melanoma Mimicker: Pigmented Mammary Paget Disease in a Man

ABSTRACT

Male breast cancer comprises less than 1% of all breast cancer cases. Mammary Paget disease (MPD) represents a subset of breast cancer that presents with skin changes of the nipple and areola, and is frequently misdiagnosed clinically due to similarities with other disease states, leading to an average delay in diagnosis of 1 month to 2 years. Pigmented mammary Paget disease (PMPD) is an uncommon variant of MPD that clinically and histologically resembles malignant melanoma. Due to variable immunohistochemical staining patterns, analysis can be challenging and often requires interpretation of panels for accurate diagnosis. We present a rare case of PMPD in a male, originally diagnosed both clinically and histologically as malignant melanoma, to highlight the diagnostic challenges that this entity presents, and to review staining patterns which may be useful in its diagnosis.

HER2 Negative Mammary Paget's Disease or In Situ Melanoma? A Case Report and Review of the Literature

Mammary Paget's disease (MPD) is a rare histological condition, accounting for 1-4% of female breast cancers, which may appear either independently (1.4-13% of the cases), or in association with an in situ or invasive ductal carcinoma (approximately 90% of the cases). The purpose of this article is to highlight the histopathological challenges related to the microscopical polymorphism of this disease and the utmost importance of immunohistochemistry in the thorough process of Paget's disease differential diagnosis. Moreover, the primary objective of this review of literature was to corroborate the existing data concerning the potential peculiar immunohistochemical profile that mammary Paget's disease might express. We report the case of a 44-year-old female patient, histopathologically diagnosed with HER2-negative MPD accompanying an invasive mammary carcinoma. The histopathological and immunohistochemical approach is derived from the exigency of excluding the possibility of synchronous tumors-a mammary invasive carcinoma, accompanied by another component with MPD phenotypic mimicry. The unexpected negative HER2 reaction is conducted to a primary focus on excluding a malignant melanoma in situ. The absence of MelanA and S100 immunoexpression and lack of pigmentation and clinical aspects infirmed it. Bowen's disease was invalidated by its rare presentation in the breast cutaneous tissue and the absence of individual risk factors suggestive of an existing immunosuppressive status. In the case of similar morphoimmunohistochemical aspects, significant expression of Ki-67 signals MPD, an immunoreactivity that helped distinguish the cellular population from Toker cells. The great similarity of MPD with other benign and malignant cutaneous tumors might determine delay or misdiagnosis. Thus, the utmost importance of immunohistochemistry is reflected in its prognostic significance and geared towards extending the therapeutic arsenal.

Role of GATA3 as a potential adjunct marker in the differential diagnosis of Paget’s disease of the nipple

Aims

Paget’s disease of the nipple (PDN) is a rare type of cancer of the nipple-areola complex. We examined GATA3 protein expression in PDN to determine its potential value as an adjunct marker in the differential diagnosis with other nipple lesions.

Methods and results

Chart review documented clinicopathological data. H&E slides were re-evaluated and immunohistochemistry (IHC) for GATA3 was performed. Amongst 3614 breast cancer patients, 74 had PDN and 41 cases were selected for our study (mean age, 55 years). Amid PDN cases, 4 (10%) patients showed PDN alone, 22 (65%) had an underlying ductal carcinoma in situ and 15 (37%) had invasive breast carcinomas (IBC), including 11 invasive carcinoma of no special type, 2 lobular, 1 mucinous and 1 micropapillary carcinoma. Additionally, 9 cancers were classified as luminal B, 4 as HER2 overexpression and 2 as luminal A. GATA3 expression was detected in all 41 PDN cases and in all underlying cancers. Furthermore, IHC for S-100, HMB45 and Melan-A was performed in PDN-only, ensuing negative results. Positivity for cytokeratin 7 or AE1/AE3 was demonstrated in all cases and HER2 overexpression was seen in 2/4 lesions. GATA3 expression was noted in all lesions, including one CK7-negative case.

Conclusion

Our findings indicate that GATA3 is consistently expressed in PDN. Although not entirely specific, positivity for GATA3 reinforces the non-melanocytic nature of PDN and its mammary origin, thus representing a potential adjunct tool for the diagnosis of PDN in tricky situations, particularly PDN variants or unusual lesions.

Mammary Paget Disease With Melanocytic Proliferation Mimicking Malignant Melanoma in situ: A Case Report

Several cases of pigmented mammary Paget’s disease (PMPD) mimicking cutaneous malignant melanoma have been reported. In these cases, the tumor cells are colonized by melanocytes, particularly with the presence of a population of melanocytes staining for HMB-45 and S100. Here, we report a case of mammary Paget disease (MPD) which was misdiagnosed as melanoma in situ due to the interpretation of the staining of melanocytic markers S-100, Melan-A, and HMB-45. The tumor cells strongly expressed CK7 and GATA3, and a dual-labeling showed negative PHH3 labeling for the melanocytes. Pathologists need to be aware of the caveat of colonization of melanocytes in Paget disease.