赤色変性様の画像所見を呈した子宮平滑筋肉腫の1例

A case of uterine leiomyosarcoma mimicking red degeneration

子宮平滑筋肉腫は子宮肉腫の中で最も多い組織型であるが，全子宮悪性腫瘍の中では1～2％程度のまれな腫瘍であり，子宮上皮性腫瘍に比して非常に予後が悪く，再発や転移も高頻度にみられる^1）2）。近年では子宮動脈塞栓術，内分泌療法，MRIガイド下収束超音波療法など侵襲度が低い治療法が発達しているが，組織検体を得られず病理学的な評価ができないため，術前の画像診断の重要性は高い^1）3）。

A 50-year-old woman presented with atypical genital bleeding. Contrast-enhanced MRI demonstrated a nonenhancing myometrial mass with a peripheral rim showing high intensity on T1WI and low intensity on T2WI. These findings were similar to those of red degeneration. Additionally, a small enhancing lesion was found close to the mass. On follow-up MRI, the enhancing lesion increased, which partly showed high intensity on T1WI. The mass was pathologically proven as leiomyosarcoma. It is important to recognize that some uterine leiomyosarcomas can show imaging findings resembling leiomyomas with red degeneration.