Metachronous vulvar ectopic breast cancer, a case report and literature review

Supplementary data associated with this article can be found, in the online version, at https://doi.org/10.1016/j.gore.2019.100515. Ectopic breast tissue, which extends from axilla to groin, is a rare finding in the general population with an incidence of 1–2%. Ectopic breast tissue may respond to physiological stresses and hormonal stimulation and develop benign and malignant histopathologic changes similar to those seen in normal breast tissues, including invasive and in situ carcinoma (Kitamura et al., 1995). Although breast cancer is the most common malignancy in women, both metastatic and primary breast cancer arising from the vulva are extremely rare and only a limited number of cases have been published in the literature (Cokmert et al., 2014, Kitamura et al., 1995). Breast carcinoma may be present in the vulva as either a distant metastasis or as a primary carcinoma arising in ectopic mammary tissue. Differentiating synchronous or metachronous breast carcinoma in the vulva from a metastatic lesion can be challenging. Although there have been 30 previously reported cases of cancer arising in vulvar breast ectopic tissue, to the best of our knowledge, based on a Medline search with search terms including ‘vulvar breast cancer’, ‘ectopic breast cancer’, and ‘metachronous/synchronous breast cancer’, there have been only three previously reported cases of synchronous or metachronous vulvar ectopic breast cancer (Guerry and Pratt-Thomas, 1976, Intra et al., n.d., Li et al., 2019) (Supplementary Table 1). In this report we describe the challenges in diagnosis and management of a patient with primary carcinoma of the breast and vulvar ectopic breast tissue. Supplementary Table 1 Click here to view.(49K, docx) 2. Case report Our patient is a 43-year-old Caucasian female who was initially diagnosed with nuclear grade 3 infiltrating ductal carcinoma with associated ductal carcinoma in situ of the right breast. Her tumor was noted to be strongly estrogen receptor (ER) positive, progesterone receptor (PR) negative, and Her2 positive by fluorescent in situ hybridization. One month after diagnosis she underwent a lumpectomy and sentinel node biopsy. All three sentinel nodes and two non-sentinel nodes were negative, consistent with a Stage I breast cancer. However, the posterior margin of the tumor was positive and she underwent re-excision later in the same month with subsequent negative tumor margins. After surgery, she was treated with 12 cycles of weekly Taxol and Herceptin over one year. Tamoxifen was started seven months after her diagnosis and was continued for one year. Three months after discontinuation of Taxol and Herceptin, and 17 months after her initial breast cancer diagnosis, the patient noted new vulvar lesions for which she was assessed by her primary obstetrician gynecologist and ultimately referred to gynecologic oncology. She was noted to have a nodular, subdermal lesion on the left labia majora and minora. Due to her history of breast cancer a metastatic workup was ordered, including CT chest, abdomen, and pelvis, with no evidence of metastasis. She underwent a left simple partial vulvectomy and reconstruction as well as dilation and curettage of the endometrium. Initial pathology impression of the vulvar tissue was multifocal metastatic carcinoma consistent with known breast primary, but upon further review the vulvar tumor was noted to be Her2 amplified and ER and PR positive whereas the breast primary was ER positive but PR negative. In addition, the morphologic features of the carcinoma in the vulva were different from those of the patient’s primary breast carcinoma (Fig. 2). This discrepancy prompted reexamination of the tumor, revealing multifocal invasive carcinoma associated with rare foci of non-neoplastic ectopic breast lobules and ductal carcinoma in situ. Immunohistochemical staining of the tumor was positive for GATA3, mammaglobin, and CK7; and was negative for CK20 (Fig. 3). The in situ component was positive for ER, PR, mammaglobin, P63, and Calponin (Fig. 4). This staining pattern is consistent with the presence of myoepithelial cells overlying an in situ carcinoma. The revised diagnosis was consistent with a primary poorly differentiated ductal carcinoma with pagetoid spread within the epidermal surface, arising from ectopic breast tissue in the vulva. Open in a separate window Fig. 2 Hormone receptor status of breast versus vulvar tumor. A-D Initial lesion in the breast, ER positive, PR negative, and HER2 positive. E-H Vulvar lesions, ER positive, PR positive, and HER2 positive. The two lesions have differing hormone receptor expression patterns.