while over 90% of vulvar malignancies are squamous cell carcinomas , other histologic types include melanomas , basal cell carcinomas , sarcomas , extramammary paget 's disease , and bartholin gland adenocarcinomas .
 ectopic breast tissue  in the vulva was first described by hartung in 1872 , and since that time , several cases of both benign and malignant lesions arising in vulvar mammary tissue have been reported ( van der putte , 1994 ) .
the histology of the mammary - like tissue has multiple forms , ranging from simple , wide , slightly coiled tubular glands with a smooth outline , to more complicated forms in which the coiled structure has numerous branches and acini forming lobules .
similar to normal breast tissue , both epithelial and myoepithelial cells are present and the glands are subject to both the dysplastic and malignant changes that are seen in normal breast tissue ( van der putte , 1994 ) . we report a case of a mammary - like invasive carcinoma presenting as an asymptomatic vulvar nodule .
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 12  years prior , after which she was diagnosed with right breast ductal papilloma which was excised .
in 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
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 . the 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 .
microscopic examination revealed invasive carcinoma , at least 1.6  mm in greatest dimension ( fig .  1 ) , 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 .
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 ( fig .  2 ) .
the area of concern demonstrated an irregular growth pattern ( no longer lobulocentric ) and was not associated with the prior biopsy site changes .
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 .
secondary 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 .
a relative paucity of reports has documented complications of ectopic breast tissue in the vulva , beginning with hartung in 1872 .
mammary ridges were theorized to have developed in a line from the axilla to the groin , and while the large majority of these ridges would normally regress , it was possible for rudimentary tissue to persist and develop into supernumerary mammary tissue ( van der putte , 1994 ) .
these mammary - like glands have an unknown function , but were distinguished from eccrine and apocrine glands .
the glands are simple tubular structures and are sparsely concentrated ; however , in some women they are more numerous and assume more complicated forms that resemble mammary tissue ( van der putte , 1994 ) .
the more complicated forms contain the basic coiled structure , but are obscured by numerous branches and acini which form lobules .
they are distinctly different from eccrine and apocrine glands by multiple factors including : 1 ) the type of epithelium , 2 ) the formation of diverticula , branches , and lobuli , 3 ) the shedding of clusters of epithelium , and 4 ) the expression of receptors for estrogen and progesterone .
additionally , mammary - like glands are also noted to be different than normal mammary tissue derived from the mammary ridges for multiple reasons as well : 1 ) their simpler configuration , 2 ) the higher number of glands than would be expected in rudimentary elements from mammary ridges , and 3 ) the direct relationship to eccrine glands .
furthermore , based on human embryologic studies , the mammary ridges could not involve the anogenital area , as at the height of the formation of the mammary ridges in 9  mm and 10  mm embryos , the labia majora are still far from their first appearance ( van der putte , 1994 ) .
however , ectopic breast tissue has been described in the vulva , as well as in any other area of the body .
both ectopic breast tissue and mammary - like glands are susceptible to the physiologic , dysplastic , and malignant changes seen in normal breast parenchyma ( castro and deavers , 2001 ) , as there have been reported cases of invasive ductal carcinoma , ductal carcinoma in situ ( dcis ) , lobular carcinoma , mucinous adenocarcinoma , phyllodes tumors , and fibroadenomas in accessory breast tissue in the vulva ( lopes et al . , 2006 ) .
although ectopic mammary tissue in the vulva is believed to be present in two to six percent of women , few cases of invasive ductal carcinoma have been reported in the literature ( kazakov et al . , 2011 ) .
the most common clinical presentation is a painless , solitary nodule , arising most often in the labia majora .
patient age at presentation has been between 45 and 84  years , with most being 60 or older ( kazakov et al . ,
most carcinoma cases are histologically consistent with invasive ductal carcinoma , which is also the most common histology in orthotopic breast tissue ( kazakov et al . , 2011 ) .
this still leaves a differential diagnosis of primary mammary carcinoma , carcinoma of a skin appendage , or metastatic mammary carcinoma .
recognition of an in situ component is the best clue to establishing the primary origin in the skin , as was seen in our case , rather than a metastatic process ( kazakov et al . , 2011 ) .
secondary to the rarity of these lesions , there is no widely accepted recommended management strategy .
a recent review only identified approximately 25 cases reported in the literature ( benito et al . , 2013 ) .
management strategies have ranged from wide local excision for dcis to radical vulvectomy with bilateral inguinofemoral nodal dissection for invasive carcinomas ( irvin et al . , 1999 ) .
adjuvant therapies have included radiation , anthracycline - based chemotherapy , and hormonal therapy , in an attempt to decrease recurrence and improve survival .
patients that did not receive adjuvant therapy had a median survival of 4  months ( lopes et al . , 2006 )
. only 1 patient out of 8 who received adjuvant therapy had died at the time of the previous publications , and the median survival was greater than 22  month ( lopes et al . , 2006 , irvin et al . , 1999 ) .
not surprisingly , there have been no clinical trials to evaluate the effectiveness of chemotherapy and radiation in such a small number of patients , so information on treatment has been , and should continue to be , extrapolated from treatment of cancers in the breast  i.e. excisional procedure with or without lymph node dissection , followed by other adjuvant therapies as needed .
there is little to no data reporting on the utility of sentinel lymph node biopsy in this clinical scenario .
breast carcinoma is almost exclusively managed using sentinel lymph node mapping ( krag et al . , 2010 ) , while promising data support the use of this technique for vulvar cancer ( levenback et al . , 2012 ) .
vulvar cancer is ideally suited for sentinel lymph node mapping secondary to the predictable lymphatic drainage of the vulva , the low false negative rate , and the substantially reduced morbidity ( e.g. lymphedema ) compared to a full groin lymph node dissection ( levenback et al . , 2012 ) .
we demonstrate this to be a potentially feasible technique for primary breast adenocarcinomas arising within the vulva in mammary - like glands , and in the context of such a rare histology , may be included in the management options of this disease .
 highlightsprimary invasive breast carcinoma can be found arising from within mammary - like glands in the vulva.there is no standard management strategy for this rare disease ; treatment recommendations should be similar to that for primary breast carcinoma.the use of sentinel lymph node biopsy may offer another management option for this disease . 