PATHOLOGY RESEARCH AND PRACTICE © Urban & Fischer Verlag Angiomyofibroblastoma and Aggressive Angiomyxoma: Two Benign Mesenchymal Neoplasms of the Female Genital Tract. An Immunohistochemical Study Giulio Bigotti 1 , Antonella Coli 1 , Alessandra Gasbarri, Diana Castagnola 2 , Vinicio Madonna 3 and Armando Bartolazzi 3 lDepartment of Pathology, Catholic University of Sacred Heart, Rome, Italy; 2Department of Pathology, Sandro Pertini Hospital, Rome, Italy; 3Department of Pathology, Regina Elena Cancer Institute, Rome, Italy Summary We describe a rare case of angiomyofibroblastoma (AMF) of the vulva and one case of aggressive an- giomyxoma (AAM) of the pelvic region and, with the help of an extensive revision of the literature, we at- tempt to define their histogenesis and peculiar biological behaviour by an immunohistological evaluation. Our re- sults indicate that AAM, which is characterized by the presence of a high content of glycosaminoglycans in the stroma, expresses uniformly vimentin and hyaluronate receptor CD44, and heterogeneously muscle specific actin (MSA) and desmin, while AMF displays a positive reaction for vimentin, desmin and laminin, and only a weak and heterogeneous positivity for CD44. Both AMF and AAM showed no immunohistochemical reac- tivity for alpha-smooth muscle actin (ASMA), myo- globin, cytokeratin, collagen type IV, CD68 and S-100. The stromal cells of AAM were negative for laminin. These findings support the suggestion of an origin of the two entities by a common myofibroblastic progenitor, which normally occurs in the lower female genital tract and subsequently undergoes a neoplastic transforma- tion. The expression of CD44 by AAM, which has never been reported before, could be responsible for its more aggressive behaviour, because this receptor is able to mediate migration of neoplastic cells on a hyaluronate rich extracellular matrix. It is speculated that the neo- plastic cell of the AAM and AMF of the vulva is a spe- Pathol. Res. Pract. 195: 39-44 (1999) cific myofibroblast which probably arises from undiffer- entiated mesenchymal cells normally occurring in the lower female genital tract. Key words: Angiomyofibroblastoma - Aggressive an- giomyxoma - Myofibroblast - Immunohistochemistry Introduction Angiomyofibroblastoma (AMF) is a rare tumor de- scribed by Fletcher et al. in 1992 [15]. It is an unusual benign tumor which arises predominantly in the vulvar region. This tumor displays histological, immunohisto- chemical and ultrastructural characteristics suggestive of myofibroblastic differentiation. Histologically it can be confused with aggressive angiomyxoma (AAM), a distinctive, locally infiltrative but non metastasizing, mesenchymal neoplasm occurring with predilection in the pelvic and perineal region of females. In this report we present an immunohistochemical study performed on a case of AMF and a case of AAM. With the help of an extensive revision of the literature, we attempt to better define these entities. Address for correspondence: Dr. G. Bigotti, Department of Pathology, Catholic University of Sacred Heart, Largo F. Vito I, 1- 00168 Rome, Italy. Fax: 06/3 05 13 43; Tel.: 06/30 154270 or 30154532 0344-0338/99/195/1-039 $12.00/0