Angiomyofibroblastoma and aggressive angiomyxoma: Two benign mesenchymal neoplasms of the female genital tract. An immunohistochemical study

We describe a rare case of angiomyofibroblastoma (AMF) of the vulva and one case of aggressive angiomyxoma (AAM) of the pelvic region and, with the he lp of an extensive revision of the literature, we attempt to define their h istogenesis and peculiar biological behaviour by an immunohistological eval uation. Our results indicate that AAM, which is characterized by the presen ce of a high content of glycosaminoglycans in the stroma, expresses uniform ly vimentin and hyaluronate receptor CD44, and heterogeneously muscle speci fic actin (MSA) and desmin, while AMF displays a positive reaction for vime ntin, desmin and laminin, and only a weak and heterogeneous positivity for CD44. Both AMF and AAM showed no immunohistochemical reactivity for alpha-s mooth muscle actin (ASMA), myoglobin, cytokeratin, collagen type IV, CD68 a nd S-100. The stromal cells of AAM were negative for laminin. These finding s support the suggestion of an origin of the two entities by a common myofi broblastic progenitor, which normally occurs in the lower female genital tr act and subsequently undergoes a neoplastic transformation. 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 neoplastic cell of the AAM and AMF of the vulva i s a specific myofibroblast which probably arises from undifferentiated mese nchymal cells normally occurring in the lower female genital tract.