Figure 2: A less cellular area highlights the fibrillary stromal collagen. (H&E, x200).
Figure 3: Perivascular spindle cells exhibit cytoplasmic reactivity for desmin (x200).
Intralesional fat was present in 24% of both female and male cases, and it seemed not to be as prominent or as frequent as suggested in prior smaller studies[3]. Additionally, both tumors exhibit an immunoprofile including strong and diffuse vimentin immunoreactivity and variable expression of desmin reactivity. SMA, CD34 and estrogen and progesterone receptor proteins are expressed but there is no expression of S-100 protein[7,11]. The immunoprofile of the male neoplasm, although still consistent with myofibroblastic differentiation, varied slightly from the female AMF. Desmin expression was noted in 37.5% whereas the figure is 94% for the female AMF reported in the literature. 50% reacted with SMA, whereas this figure is only 15% for all female AMF. The mean estrogen and progesterone receptor scores were substantially higher in the female AMF[7]. The immunoreactivity of neoplastic cells for desmin is a common finding in angiomyofibroblastoma; it is occasionally desmin negative, especially in examples arising in male patients[1,6]. Histogenetically, Laskin WB et al. believes that the male AMF-like tumor, like the female AMF, is derived from a perivascular stem cell with a capacity for fatty and myofibroblastic differentiation governed by hormonal, microenvironmental, and growth factor/cytokine-related influences[2]. This progenitor cell may be related to the CD34-positive fibroblast like cell that normally resides around vessels. A CD34-positive fibroblast like cell composes the spindle cell element of spindle cell lipoma. In the male AMF-like tumor, this cell may theoretically lose its ability for CD34 expression with myofibroblastic differentiation[4,7].
Aggressive angiomyxoma, solitary fibrous tumor, spindle cell lipoma, angiomyofibroblastoma, schwannoma, hemangiopericytoma, well differentiated liposarcoma and malignant fibrous histiocytoma, are considered in the histological differential diagnosis of AMF-like tumor[1,5].
Aggressive angiomyxoma of the perineal and pelvic soft tissues of women has also been described in the scrotum, perineum, and inguinal region of men. Microscopically, it has an infiltrative growth pattern and a less conspicuous vascular component, which exhibits greater variability in size and distribution of vessels. Small clusters of smooth muscle cells surrounding blood vessels are a characteristic feature of aggressive angiomyxoma. The stromal matrix of the aggressive angiomyxoma is more loosely textured and contains less acid mucin than the stroma of male AMFlike tumors. Tumor cells of aggressive angiomyxoma are immunoreactive for desmin[1,3,5,7].
Solitary fibrous tumor has been reported in a wide variety of locations, including the inguinal region, perineum, and tunica vaginalis of the testis. Microscopically, solitary fibrous tumor is typically well circumscribed and shows a patternless spindle cell proliferation of alternating hypocellular and hypercellular areas, often associated with dense hyaline collagen bundles, stromal hyalinization, and hemangiopericytoma- like vessels. Angiomyofibroblastoma-like tumors lack the keloid-type collagen and hemangiopericytoma-like areas that are distinctive of solitary fibrous tumors. The tumor cells of solitary fibrous tumor may also focally express desmin and actin, but they usually exhibit a stronger and more diffuse staining for CD34[1,3,6,7].
Spindle cell lipoma overlaps AMF-like tumor in several clinicopathological features, including subcutaneous location, age distribution, circumscription, and the presence of spindle cells and adipose tissue. However, most spindle cell lipomas arise in the posterior neck, shoulder, and back regions. Spindle cell lipoma consists of mature adipocytes, bland spindle cells, and short bundles of brightly eosinophilic ropy collagen. The blood vessels are usually inconspicuous, whereas the lesion is composed of wispy collagen fibers and numerous small-to mediumsized thick-walled vessels are present[1,3,10].
Neurilemmoma (benign schwannoma) and neurofibroma typically possess tumor cells with more irregular nuclear contours than the neoplastic cells composing the male AMF-like tumor. Neurilemmoma characteristically demonstrates an alternating pattern of cellular Antoni A foci with hypocellular Antoni B areas. The growth pattern of cells in neurofibroma may be haphazard like that of the male AMF-like tumor, but the former lesion is less vascular[7]. Although both peripheral nerve sheath tumors may express CD34, they more commonly express S–100 protein[12].
Hemangiopericytoma features greater vessel density and more variability in vessel size and shape than the vessels in male AMF-like tumors. The lesional cells in hemangiopericytoma are also typically less spindled. Although the neoplastic cells of both lesions may express CD34, the tumor cells of hemangiopericytoma typically lack desmin expression[7].
Liposarcomas, particularly the spindle cell variant of well-differentiated liposarcoma and myxoid liposarcoma, are the most important differential diagnoses clinically as liposarcomas require wide resection. Liposarcoma commonly arises in deep soft tissue, whereas AMF-like tumor arises in subcutaneous tissue. The spindle cell variant of well-differentiated liposarcoma arises superficially and consists of spindled cells and adipose tissue. It differs from AMF-like tumor because of the presence of lipoblasts[1].
Low-grade myxoid malignant fibrous histiocytoma (myxofibrosarcoma) differs from the tumors in our study by exhibiting a more infiltrative growth pattern and cytologically atypical spindled and stellate cells, often accompanied by an intricate network of curvilinear vessels[5,13].
The recommended treatment is wide excision with tumorfree margins, close postoperative monitoring, and longterm follow-up exams. Any suspected recurrence should be imaged and explored. Radiation and chemotherapy play no role in the treatment of this tumor[3].
In conclusion, angiomyofibroblastoma and AMF-like tumors are rare, distinctive, slow-growing, potentially recurrent mesenchymal neoplasms of the female vulva, perineum, or pelvis and male scrotum or inguinal canal. The diagnosis of AMF-like tumor is based on several findings such as superficial location, well-marginated nature of the tumor, spindle bland epithelial cells, numerous small and medium sized vessels with fibrinoid and hyalinized walls set in an edematous collagenous stroma, and low mitotic activity.
1) Miyajima K, Hasegawa S, Oda Y, Toyoshima S, Tsuneyoshi M, Motooka M, Matsuura Y, Ishioka H, Ono M: Angiomyofibroblastoma-like tumor (cellular angiofibroma) in the male inguinal region. Radiat Med 2007, 25:173-7. [ Özet ]
2) Laskin WB, Fetsch JF, Mostofi K: Angiomyofi broblastomalike tumor of the male genital tract: analysis of 11 cases with comparison of female angiomyofi broblastoma and spindle celllipoma. Am J Surg Pathol 1998, 22:6–16. [ Özet ]
3) Magro G, Greco P, Alaggio R, Gangemi P, Ninfo V: Polypoid angiomyofibroblastoma-like tumor of the oral cavity: a hitherto unreported soft tissue tumor mimicking embryonal rhabdomyosarcoma. Pathol Res Pract 2008, 204:837-43. [ Özet ]
4) Iwasa Y, Fletcher CD: Cellular angiofibroma: clinicopathologic and immunohistochemical analysis of 51 cases. Am J Surg Pathol 2004, 28:1426-35. [ Özet ]
5) Hara N, Kawaguchi M, Koike H, Nishiyama T, Takahashi K: Angiomyxoid tumor with an intermediate feature between cellular angiofibroma and angiomyofibroblastoma in the male inguinal region. Int J Urol 2005, 12:768-72. [ Özet ]
6) Canales BK, Weiland D, Hoffman N, Slaton J, Tran M, Manivel JC, Monga M: Angiomyofibroblastoma-like tumors (cellular angiofibroma). Int J Urol 2006, 13:177-9. [ Özet ]
7) Nucci MR, Granter SR, Fletcher CD: Cellular angiofibroma: a benign neoplasm distinct from angiomyofibroblastoma and spindle cell lipoma. Am J Surg Pathol 1997, 21:636–644. [ Özet ]
8) Fletcher CD, Tsang WY, Fisher C, Lee KC, Chan JK: Angiomyofibroblastoma of the vulva. A benign neoplasm distinct from aggressive angiomyxoma. Am. J. Surg. Pathol 1992, 16: 373–82. [ Özet ]
9) Lee SH, Yang JW, Do JM, Seo DH, Jung JH, Chung KH, Lee JS, Hyun JS : Angiomyofibroblastoma-like tumor of the scrotum. Korean J Urol 2010, 51: 365-7. [ Özet ]
10) Shintaku M, Naitou M, Nakashima Y: Angiomyofibroblastoma-like tumor (lipomatous variant) of the inguinal region of a male patient. Pathol Int 2002, 52:619-22 . [ Özet ]
11) Ito M, Yamaoka H, Sano K, Hotchi M: Angiomyofibroblastoma ofthe male inguinal region. Arch Pathol Lab Med 2000, 124:1679- 81. [ Özet ]
12) Weiss SW, Nickoloff BJ: CD-34 is expressed by a distinctive cell population in peripheral nerve, nerve sheath tumors, and related lesions. Am J Surg Pathol 1993, 17: 1039-45. [ Özet ]
13) Mentzel T, Calonje E, Wadden C, Camplejohn RS, Beham A, Smith MA, Fletcher CD: Myxofibrosarcoma. Clinicopathologic analysis of 75 cases with emphasis on the low-grade variant. Am J Surg Pathol 1996, 20:391-405. [ Özet ]