Primary invasive breast carcinoma arising in mammary-like glands of the vulva managed with excision and sentinel lymph node biopsy
A 65 year old, multiparous, postmenopausal female status-post total hysterectomy with bilateral salpingo-oophorectomy 39 years prior for symptomatic myomatous uterus, presented for her annual well woman exam. She was without complaints and review of systems was negative; specifically, she denied any recent history of unintended weight loss or gain, fever, chills, nausea, melena or hematochezia, vaginal bleeding or discharge, abdominal pain or fullness. Her last mammogram was 1–2 years prior, after which she was diagnosed with right breast ductal papilloma which was excised. Colorectal screening was up to date.\nIn addition to her prior hysterectomy, gynecologic history was significant for estrogen replacement therapy for 20 years, which she stopped after developing what she reported as “vaginal cysts.” Two years prior to presentation, she had such a lesion removed from her right labia that had been present for one year and pathology was benign, per patient. On further discussion, she reported that the lesion had returned, was not painful, and was not associated with any further growth for the last six months. Clinical breast examination did not demonstrate evidence of palpable masses, retraction, skin changes, or axillary adenopathy. Genital examination revealed a mobile, soft, non-tender, 2.5 × 0.75 cm nodule at 11 o'clock on her right labia majora. Excisional biopsy was performed in clinic, which revealed ductal carcinoma in situ with positive margins. The patient then underwent a wide local excision of the area, which pathologically revealed invasive carcinoma with negative margins.\nThe specimen from the wide local excision revealed a surface which was predominantly dark brown and wrinkled with a smooth, white, flat lesion measuring 0.8 × 0.3 cm; the lesion was 1.2 cm from the 12 o'clock margin and 0.4 cm from the nearest (3 o'clock) margin. On serial sectioning, the lesion was firm and white, and extended to a depth of 0.3 cm.\nMicroscopic examination revealed invasive carcinoma, at least 1.6 mm in greatest dimension (), arising from within a background of mammary-like glands of the vulva demonstrating residual focal DCIS. The invasive lesion was noted to come within 1.3 mm of the margin, but all margins were negative for invasive disease. The histologic features were consistent with a primary carcinoma, not a metastatic lesion. Immunohistochemical (IHC) stains including smooth-muscle heavy chain (SMM-HC), CD 10, and p63 were performed and while there appeared to be some myoepithelial cells present along the smooth contoured edge by SMM-HC only, there were other areas without any definitive basal cell/myoepithelial cell staining (). The area of concern demonstrated an irregular growth pattern (no longer lobulocentric) and was not associated with the prior biopsy site changes. The residual mammary-like ducts () exhibited strong immunoreactivity for all 3 IHC stains. The tissue was then tested for hormone receptor status, and was found to be estrogen receptor (ER) positive, but progesterone receptor (PR) and HER2/CEP17 negative.\nSecondary to narrow margins, re-excision was performed as well as an ipsilateral groin sentinel lymph node dissection, both of which were negative for DCIS or malignancy. After referral to a medical oncologist, she was also administered letrozole, an aromatase inhibitor, as adjuvant therapy for the ER positive cancer. 18 months after excision, she is without evidence of recurrent disease.