MRI診斷左小腿促結締組織增生性小圓細胞腫瘤一例

韓曉兵，張乾營，阿浣

HAN Xiao-bing, ZHANG Qian-ying, A Huan

MRI診斷左小腿促結締組織增生性小圓細胞腫瘤一例

韓曉兵，張乾營，阿浣

HAN Xiao-bing, ZHANG Qian-ying, A Huan

患者女，27歲，發現左小腿漸進性增大腫物1個月余入院。于入院前1個月患者無明顯誘因出現左小腿外側腫痛，站立時間較長、行走久時癥狀明顯，無低熱、盜汗、夜重晝輕等不適，與天氣變化無關，仍可行走及鍛煉。MRI檢查：左小腿上段偏外側軟組織可見不規則分葉狀軟組織腫塊，T1WI呈稍低信號(圖1A)，T2WI呈混雜低信號，內部見斑點狀稍高信號(圖1B)，T2脂肪抑制相腫塊呈混雜信號(圖1C)，范圍約4.3 cm×6.9 cm，邊界不清，其內可見流空血管影，病灶鄰近周圍軟組織可見斑片狀水腫，T1WI增強掃描示腫塊呈明顯不均勻強化，并可見不強化壞死區域(圖1D)；鄰近左腓骨上段骨皮質連續，骨髓腔內在T2脂肪抑制相上可見斑片狀高信號，邊界不清。術中所見：左小腿外側上段腫物，腫物無明顯界限，活動度差，腫物呈分葉、灰白色、魚肉狀。術后病理：瘤組織排列成不規則細胞巢，細胞排列緊密，核呈圓形或卵圓形，深染，核仁不清，核分裂象易見，胞質稀少，瘤細胞巢間及其周圍為大量增生的致密纖維結締組織，部分伴有玻璃樣變性。免疫組化標記結果：CD99(+++)，SMA (－)，Desmin (－)，CgA (－)，Syn(－)，CD56 (－)，EMA (－)，LCA (背景淋巴細胞+)。病理證實為促結締組織增生性小圓細胞腫瘤(desmoplastic small round cell tumor，DSRCT)。

討論 1989年Gerald和Rosail首次報道本病[1]，并1991年正式命名[2]。DSRCT是由組織起源未定的小圓腫瘤細胞構成，伴有明顯間質硬化和表型分化的高度惡性腫瘤，好發年齡為18～25歲，男女比例為3.8～5:1，但也有報道老人和年輕女性可患此病[3-4]，基本發生在腹腔內，偶見胸腔、睪丸區及頭頸部[5-8]，筆者復習查閱既往文獻，尚無發生于小腿的病例報道，流行病學特征有待大宗病例統計。張沈榮等[9]和Pickhardt等[10]認為DSRCT最典型的征象是沒有明確的起源器官，多數病灶位于大網膜、腸系膜根部或者膀胱周圍，表現為孤立性、多發性的軟組織腫塊。影像學檢查是DSRCT術前的主要檢查手段，但不能明確性質，確診得依靠病理。CT或MRI可發現單個或多個分葉狀軟組織腫塊，內部可見壞死，偶見鈣化，增強呈不均勻強化。本病在病理學及影像學上發生于腹腔外的與腹腔內的無明顯區別，但發生于四肢的病例需與以下病變鑒別：(1)未分化高級別多形性肉瘤：多見于老年(60～70歲)男性，好發于下肢深部軟組織，邊界不清，易侵犯鄰近骨質結構和發生遠處轉移，與發生于老年人的DSRCT并無可鑒別的特殊征象。(2)黏液纖維肉瘤：多見老年男性，且發生于四肢的皮下軟組織，影像特征不明顯，一般T1WI及T2WI為混雜信號。(3)平滑肌肉瘤：中老年人多見，好發于腹腔、腹膜后等，四肢亦可發生，相對較少見，四肢中下肢深部軟組織多見，易出血、壞死，MRI表現多呈等T1WI信號，稍長T2WI信號，與發生于四肢的DSRCT亦難以鑒別。(4)惡性外周神經鞘瘤：好發于成年人及老人，T1WI、T2WI多呈等信號，瘤內易囊變、壞死及鈣化，瘤周可見水腫帶，增強掃描腫瘤實性成分呈中等強化，本病例多見于青年，增強呈明顯不均勻強化。

圖1 病灶位于左小腿上段偏外側軟組織，鄰近左腓骨上段骨質受累。A：T1WI示病灶呈稍低信號，其內可見留空血管影，左腓骨上段呈稍低信號；B：T2WI示病灶呈混雜低信號，周圍可見斑片狀稍高水腫信號；C：T2WI脂肪抑制序列示病灶呈混雜信號，中央呈稍低信號，周圍水腫呈高信號；D：T1WI增強掃描示病灶呈明顯不均勻強化，周圍水腫未見強化 圖2 瘤組織排列成不規則細胞巢，細胞排列緊密，核呈圓形或卵圓形，深染，核仁不清，核分裂象易見，胞質稀少，瘤細胞巢間及其周圍為大量增生的致密纖維結締組織，部分伴有玻璃樣變性(HE ×200)Fig. 1 Focus was located in the lateral soft tissue on the upside left leg. The adjacent left fibula is involved. A: T1WI showed that the focus presents the lower signal with empty blood vessel. The left fibula presents the lower signal. B: T2WI presents that the focus were mixed with lower signals. There was the higher edema signal in a flaky shape. C: T2WI fat suppressed sequence showed that the focus presents the mixed signal. The central part showed the lower signal and surrounding edema presents the higher signal. D: T1WI enhanced scanning showed that the focus were obviously inhomogeneous and the surrounding edema was not enhanced. Fig. 2 The tumor tissue was arranged into the irregular nests of cells closely. The nucleus was round or oval. With deep stain and unclear nucleolus, nucleolus mitotic figure was obvious. Rare cytoplasm. A large number of dense fibrous connective tissue was found in the nests of tumor cells.Some were accompanied with hyaline degeneration (HE ×200).

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MRI diagnosis of desmoplastic small round cell tumor on left leg: A case report

Desmoplastic small round cell tumor; Magnetic resonance imaging

結締組織增生性小圓細胞腫瘤；磁共振成像

中國人民解放軍第一八○醫院醫學影像科，泉州 362000

Department of Medical Imaging, the 180th Hospital of People's Liberation Army, Quanzhou 362000, China

2017-04-14 接受日期：2017-06-07

R445.2；R738.6

B

Received 14 Apr 2017, Accepted 7 June 2017

10.12015/issn.1674-8034.2017.07.011