INTRODUCCIÓN

Fibroadenoma is a benign tumor consisting of mixed glandular epithelial and fibrous stromal tissue. It occurs very frequently in the breast, but its presence in the vulva is exceptional and of very low incidence. Few cases have been published in the world literature. The first case was reported by Friedel(^1), in Germany in 1932, then Fisher² in 1947, Siegler³ in 1951, Burger⁴ in 1954 and Baruah⁵ in 1967. It is indicated that there are about 50 cases.

The histogenesis of vulvar fibroadenoma is uncertain and controversial. Two hypotheses have been proposed. The first one is that it would originate in an aberrant mammary tissue in the vulva when the embryonic involution of the primitive mammary crest fails. The second hypothesis exposed by Van der Putte^6), in 1994, is that it would originate not from a true mammary tissue but from specialized anogenital glands similar to mammary glands (mammary-like glands), with strong relation to the eccrine glands that normally exist in that area. This second hypothesis had already been suggested by Champneys, in 1884^5), who considered that the supernumerary mammary glands in vulva are enlarged sweat glands or eccrine sweat glands with mammary differentiation and not true mammary tissue. Recent observations in human embryos have not shown that the migration of mammary gland cells from the primordium extends to the anogenital area; hence the concept of the presence of vulvar mammary tissue as a derivation of the primitive mammary crest is not sustainable, according to Van der Putte^6).

Vulvar fibroadenoma has been found in women between 18 and 80 years of age and clinically presents as a subcutaneous nodular mass of insidious growth, mostly sessile, with a few pedunculated cases^7). The size varies from 1 to 12 cm in diameter, although Zhang⁸ reported in an 18-year-old girl a vulvar tumor that had appeared 7 years earlier and was typified as fibroma and fibroadenoma, measuring 30 x 40 x 4 cm and weighing 2000 g. Most cases are of unilateral location, but some cases of bilateral presentation have also been published(9). The treatment is tumor excision, the prognosis is good, and no recurrence has been observed.

CASE REPORT

A 29-year-old woman presented two years ago with a tumor at the level of the perineum that grew slowly and progressively; recently it was accompanied by dyspareunia and postcoital bleeding. On gynecological examination, a subcutaneous, rounded, mobile, firm, well-defined, well-defined tumor of firm consistency, not adherent to the deep planes, was observed at the level of the right labium majus of the vulva. It was excised in its entirety (Figure 1).

Figure 1 vulvar tumor at ectoscopy. 

In pathological anatomy, a 2 x 0.8 cm skin slough with a whitish nodular subcutaneous tumor of 3 x 2 x 2 cm of major diameters was received. The external surface was smooth, well defined, regular cut (Figure 2). Microscopy showed the histology of a fibroadenoma (Figure 3A and 3B), a biphasic neoplasm composed of benign proliferation of ductal structures and dense conjunctival tissue, well delimited by scarce fibrous tissue. On immunohistochemistry, the ductal structures were positive for estrogen (Figure 4A) and progesterone receptors (Figure 4B). No glandular tissue was observed adjacent to the fibroadenoma.

Figure 2 macroscopy of the vulvar tumor, cut surface. 

Figure 3 A and b: microscopy of the vulvar fibroadenoma. 

Figure 4 iMMunohistocheMistry. A: estrogen And B: progesterone. 

DISCUSSION

Tow SH (1962)¹⁰ mentions that Hartur, in 1874, would have made the first report of a mammary gland in the vulva that presented with milky discharge. In the publication of Deber and McFarland^9,10), in 1918, of 430 cases of extramammary tissue, 90% were in the axilla, others in the thorax, abdomen and only one case in the vulva. Baruah^5), in 1967, compiled from the English literature 17 cases of mammary tissue in the vulva; in this casuistry he presented 4 cases of fibroadenoma, including his own. Kasakov¹¹, in 2011, from his personal experience published 300 cases of various lesions related to the anogenital mammary glands, both benign and malignant lesions that showed similar morphology with their mammary counterparts. In 2021, Buitrago SM collected 126 cases from 94 reports of mammary tissue in vulva and found 23 cases of vulvar fibroadenoma^12).

VULVAR FIBROADENOMA: CASE REPORT

To date, the hypothesis that the presence of specialized anogenital glands similar to the breast would be part of the normal structure of the vulva is gaining more relevance, despite the fact that the histological structure and immunohistochemical pattern are identical to those of their breast tissue counterparts. So is the presence of benign and malignant tumor lesions such as fibroma, intracystic papilloma, lactational adenoma^13), phyllodes^14), fibrocystic disease, pseudoangiomatous stromal hyperplasia, sclerosing adenosis, extramammary Paget's disease, ductal adenocarcinoma¹⁵, lobular and mucinous adenocarcinoma⁷ and sarcoma, whose behavior, clinical presentation, histology, treatment and prognosis are similar to those of the breast and with which the differential diagnosis should be made.

In conclusion, fibroadenomas located in the vulva are extremely rare. Their origin remains under debate and, despite their macroscopic characteristics of benign lesion, histologic study with relevant immunohistochemical techniques should be performed in order to have an accurate diagnosis and to rule out other vulvar tumors. We present the case to add it to the casuistry of this rare presentation.