不典型肛管直腸惡性黑色素瘤診斷并文獻復習

李鵬　鐘進　劉筠

臨床探究與評析

不典型肛管直腸惡性黑色素瘤診斷并文獻復習

李鵬鐘進劉筠

目的探討不典型肛管直腸惡性黑色素瘤的MRI表現(xiàn)、病理特征及鑒別診斷。方法回顧性分析1例經(jīng)手術病理證實的肛管直腸惡性黑色素瘤病人的MRI表現(xiàn)及病理資料，并復習相關文獻。結果MRI顯示肛管直腸交界區(qū)一T1等信號、T2稍高信號影，較為均質，呈橢圓形，大小約3.3 cm×4.2 cm×4.3 cm，直腸系膜及系膜筋膜外亦可見多發(fā)結節(jié)及腫物，大者3.2 cm×2.5 cm×3.8 cm。術中觀察顯示腫物呈實性，邊界清，表面光滑。病理診斷：惡性黑色素瘤。免疫組化顯示HMB45（+）、Melan-A（+），提示惡性黑色素瘤。結論不典型肛管直腸惡性黑色素瘤罕見，臨床及影像表現(xiàn)通常無特異性，確切診斷需依靠病理學與免疫組織化學檢查。

黑色素瘤；肛直區(qū)；磁共振成像

DOI：10.19300/j.2016.L4232

【Abstract】ObjectiveTo evaluate the MR findings and pathological features，differential diagnosis of atypical anorectal malignant melanoma.MethodsA case of anorectal malignant melanoma proved by histology was retrospectively analysed，and related literatures were reviewed.ResultsMRI scan revealed a round-like solid mass in the anorectal junction area which showed slightly long T1and long T2signal intensity，well-defined and relatively homogenous.The size of the mass was about 3.3 cm×4.2 cm×4.3 cm.Some nodules and masses were found in the mesorectal area and outside fascia，and the largest one was about 3.2 cm×2.5 cm×3.8 cm.Intraoperative observation showed that the tumor was solid，the boundary was clear，and the surface was smooth.Pathological diagnosis：malignant melanoma tumor.Immunohistochemistry showed HMB45 and Melan-A were positive，suggesting melanoma tumor.ConclusionAnorectal malignant melanoma is rare and usually does not have specific clinical and imaging manifestation.Accurate diagnosis depends on the pathological and immunohistochemical examination.

【Key words】Melanoma；Anorectal junction；Magnetic resonance imaging

Int J Med Radiol，2016，39（2）：175-178

惡性黑色素瘤最常見于皮膚，其次為黏膜組織，如直腸、肛管、外陰和鼻咽部等。一般發(fā)生于肛管直腸的黑色素瘤大多數(shù)是轉移性病變，原發(fā)于肛管直腸的黑色素瘤比較少見，通常需要排除其他部位的原發(fā)病灶后方可診斷。最終診斷依靠HMB45、Melan-A、Vimentin等免疫組織化學蛋白檢測結果判定。肛管直腸區(qū)典型黑色素瘤的MRI信號表現(xiàn)有一定特征：即T1WI上為高信號，T2WI上為低信號；不典型惡性黑色素瘤的臨床及影像表現(xiàn)均無特異性。本文就1例發(fā)生于肛管直腸交界區(qū)的惡性黑色素瘤做簡要分析并對相關文獻進行回顧總結。

1　病例資料

病人女，67歲，入院1個月前開始出現(xiàn)便中帶血，出血量不多，呈鮮紅色，不與大便相混，伴肛門下墜感，每日2～3次，不成形。……