This distinctive tumor was first delineated by Fletcher et al. in 1992 who described 10 cases involving the vulva [8
] with only one case reporting a large pedunculated mass. There is a marked predilection for the female genital tract, predominantly the vulva, although rare cases have also been reported to arise in the scrotum and the inguinal area in males [8
]. The female patients have an average age of 45.8 years [5
]. They usually complain of a painless mass that has been present from a few weeks to up to 13 years [5
]. Clinically, these tumors are frequently thought to be a Bartholin gland cyst, although a preoperative differential diagnosis includes labial cysts, inguinal hernia, leiomyoma, and mesenchymal tumors such as lipoma and liposarcoma [15
On gross examination they are typically well circumscribed and ranged from 0.5 to 12
cm. They have a soft to rubbery consistency and a bulging, pink, and somewhat lobulated sectioned surface [5
]. Microscopic examination confirms the well-demarcated nature of the lesion and shows alternating hypercellular and hypocellular edematous regions with abundant blood vessels. There is minimal nuclear atypicality, and mitotic figures are rare. The cells tend to cluster around blood vessels, sometime forming compact foci [5
]. Adipocytes can be sparsely scattered within the neoplasm and in rare cases fat predominates; these tumors have been classified as the “lipomatous” variant of angiomyofibroblastoma [16
]. The angiomyofibroblastoma can be distinguished from the aggressive angiomyxoma by its circumscribed borders, the presence of plump stromal cells that are occasionally overtly epithelioid, and perivascular condensation of the stromal cells [17
]. A single case of a malignant transformation of an AMFB in angiomyofibrosarcoma has been reported [18
]. In that tumor, areas of typical AMFB merged imperceptibly with high-grade sarcoma resembling a myxoid malignant fibrous histiocytoma.
Immunohistochemical stains show uniform staining for vimentin and staining of a variable number of cells for desmin in most cases. The tumor cells also show variable expression for muscle actin and smooth muscle actin and are frequently positive for estrogen and progesterone receptors [5
]. The expression of estrogen and progesterone receptors suggests that it might arise as a neoplastic proliferation of hormonally responsible mesenchymal cells [3
]. Some tumors have also stained for CD34, although some authors question whether these CD34 positive tumors might present fibroepithelial polyps, which are frequently positive for this marker [16
The tumor usually exists as a sharply circumscribed mass in the subcutaneous tissue of the vulva and usually does not form a pedunculated mass, which represents an exceptional event [7
]. To our knowledge, only five cases of pedunculated AMFB of the vulva have been reported in the English literature [1
All cases are reported in . All patients underwent simple excision. The mean age of patients was 46.4 years with a range of 41–50 years. The lesion always involved the labia majora. The average size of the pedunculated AMFB was of 14.2 × 13.6 centimeters in diameter (range 4 to 23
cm). Except for one case, the presence of the lesion had existed for several years. The real problem is the preoperative clinical diagnosis, as the vulvar AMFB is a rare event revealed only by histological examination after surgery. All patients had an uneventful postoperative course, and the mean followup was of 20 months (ranging from 8 months to 3 years) with no recurrence.
Clinical features of pedunculated AMFB of the vulva.
shows immunohistochemical staining for the most common antibodies in the AMFB. Almost all tumor cells were strongly positive for vimentin and desmin, but uniformly negative for cytokeratin and S-100 protein. Not all tumor cells were negative for α-smooth muscle actin and CD34. Staining for estrogen and progesterone receptors was observed in the nucleus of all tumor cells.
Immunohistochemical staining for the most common antibodies in the AMFB.
Given the data reported in the literature on the pedunculated AMFB of the vulva, our case is the first concerning a young woman of 21 years old and involving the labia minora. The patient underwent simple excision with clear margin of the lesion and currently is in followup performing clinical examination every six months for two years with no recurrence.
This paper aims to emphasize that, after excluding the most common vulvar diseases, the appearance of a pedunculated AMFB should be part of differential diagnosis in the workup of any pedunculated vulvar mass even in young women with a lesion involving the labia minora. The treatment of choice is a surgical excision with clear margins, which is resolutive as demonstrated by reported cases in the literature.