外陰部に発生した血管筋線維芽細胞腫の1例

A case of angiomyofibroblastoma of the vulva

血管筋線維芽細胞腫（angiomyofibroblastoma：AMFB）は中高年女性の外陰部や骨盤に好発する間葉系の腫瘤である。AMFBの治療は切除が基本で再発はまれであるが，同じく外陰部に発生し手術後にしばしば再発を起こす侵襲性血管粘液腫（aggressive angiomyxoma：AAM）との鑑別が臨床上重要となる。今回我々は30代女性のAMFBを経験し，AMFB，AAM，そして同じく外陰部に発生する細胞性血管線維腫（cellular angiofibroma：CAF）につき，画像的な鑑別点について考察する。

We describe a case of angiomyofibroblastoma（AMFB）in the vulva. The patient was a Japanese woman in her 30s who was referred to our hospital due to the appearance of an 18×10×7 cm mass on the vulva a few months earlier. MRI revealed a well-defined mass with low signal intensity on T1-weighted images（T1WI）and areas of high signal intensity within it, while T2-weighted images（T2WI）revealed heterogeneous high signal intensity. Contrasted fat-suppressed T1WI showed strong enhancement throughout the mass, and the area that showed high signal intensity on T1WI exhibited low signal intensity, suggesting the presence of fat. AMFB was suspected based on the imaging findings, and a resection of the vulvar tumor was performed. Postoperative pathology also confirmed the diagnosis of AMFB, which is a rare mesenchymal tumor that usually occurs in the vulva and/or pelvis of middle-aged and older women. The standard treatment of AMFB is resection, and recurrence is rare. However, it is clinically important to distinguish AMFB from aggressive angiomyxoma, which also occurs in the vulva and often recurs after surgery. We describe our general experience with AMFB and discuss the imaging differentiation of tumors arising in the vulvar region.