后腎腺瘤的CT影像特征(附1例報(bào)告并文獻(xiàn)復(fù)習(xí))

黃劍華 麥源 鐘羽翔 劉再毅 蒲小勇 徐戰(zhàn)平

·臨床研究·

后腎腺瘤的CT影像特征(附1例報(bào)告并文獻(xiàn)復(fù)習(xí))

黃劍華 麥源 鐘羽翔 劉再毅 蒲小勇 徐戰(zhàn)平

目的提高對后腎腺瘤的影像診斷水平。方法回顧性分析1例后腎腺瘤患者的臨床資料，術(shù)前CT檢查診斷為左腎嫌色細(xì)胞癌，行腹腔鏡下左腎部分切除術(shù)，術(shù)后病理確診為后腎腺瘤。結(jié)果CT提示左腎下極實(shí)性腫物，平掃期腫物邊界不清，內(nèi)部密度不均，稍低于鄰近腎實(shí)質(zhì)密度，伴有壞死灶和點(diǎn)狀鈣化，增強(qiáng)掃描腫塊呈不均勻輕度強(qiáng)化，雙期增強(qiáng)掃描呈漸進(jìn)性強(qiáng)化，強(qiáng)化程度始終明顯低于鄰近正常腎實(shí)質(zhì)。術(shù)后病理確診為后腎腺瘤。術(shù)后患者恢復(fù)良好，隨訪8個(gè)月，未見腫瘤復(fù)發(fā)。結(jié)論后腎腺瘤是罕見的腎上皮源性腫瘤，其CT影像表現(xiàn)有一定特異性，但與其他乏血供腎腫瘤難以鑒別，特別是腎嫌色細(xì)胞癌和乳頭狀腎細(xì)胞癌。術(shù)前的準(zhǔn)確診斷對選擇合適的臨床治療策略十分重要，可行術(shù)前或術(shù)中的病理檢查鑒別。

腎腫瘤； 后腎腺瘤； 診斷

后腎腺瘤是一種罕見的良性腎腫瘤，來源于腎上皮細(xì)胞。目前報(bào)道的后腎腺瘤不足200例[1]，少有報(bào)道描述其CT影像學(xué)特征。我們報(bào)告1例廣東省人民醫(yī)院收治的經(jīng)病理確診的后腎腺瘤患者，分析其CT影像表現(xiàn)，并結(jié)合國內(nèi)外文獻(xiàn)復(fù)習(xí)，探討后腎腺瘤的CT影像特征，以提高對該病的診斷水平。

病例報(bào)告

患者，女，54歲，因“體檢發(fā)現(xiàn)左腎腫物2月”于2015年12月11日入院?；颊?個(gè)月前體檢行彩超檢查發(fā)現(xiàn)左腎腫物，無腰痛、腹痛、血尿等癥狀。既往史：否認(rèn)“高血壓”、“糖尿病”等病史，否認(rèn)“肝炎”、“結(jié)核”等傳染病史，否認(rèn)食物、藥物過敏史，不吸煙，不飲酒，否認(rèn)家族遺傳性疾病病史。入院體檢：全身淺表淋巴結(jié)未觸及腫大，心肺檢查無異常，腹平軟，肝、脾、雙腎肋下未觸及，全腹無壓痛、反跳痛，Murphy’s征陰性，肝區(qū)、雙腎區(qū)無叩擊痛。雙下肢無水腫。血常規(guī)、尿常規(guī)、凝血功能、肝腎功能未見異常。彩超示左腎下極稍高回聲腫物，大小92 mm×42 mm，內(nèi)部回聲不均，考慮診斷左腎細(xì)胞癌。CT檢查提示左腎下極實(shí)性腫物，大小55 mm×51 mm×92 mm，平掃腫物邊界不清、外突，類圓形，腫物內(nèi)部密度不均，稍低于鄰近腎實(shí)質(zhì)密度，有一小片低密度的壞死灶和多個(gè)高密度的點(diǎn)狀鈣化;增強(qiáng)掃描腫物不均勻輕度強(qiáng)化，在雙期增強(qiáng)過程中呈現(xiàn)緩慢、持續(xù)的強(qiáng)化，但強(qiáng)化程度明顯低于鄰近正常腎實(shí)質(zhì)，CT診斷考慮腎嫌色細(xì)胞癌(圖1)。術(shù)前診斷：左腎癌。R.E.N.A.L評分為2+1+1+a+2=6a，予行腹腔鏡下左腎部分切除術(shù)，手術(shù)過程順利，切除標(biāo)本可見完整、邊界清楚的腫瘤，大小90 mm×60 mm×50 mm。顯微鏡下，腫瘤細(xì)胞豐富，大小較均勻一致，緊密排列成腺管樣，伴少量嗜酸性胞質(zhì)和深染的卵圓形細(xì)胞核，無明顯異型性。病理診斷符合后腎腺瘤。最后診斷：左腎后腎腺瘤。術(shù)后隨訪8個(gè)月，未見腫瘤復(fù)發(fā)。

A、B、C：分別是橫斷面的平掃期、皮質(zhì)期和髓質(zhì)期；D、E、F：分別是矢狀面的平掃期、皮質(zhì)期、髓質(zhì)期；G、H、I、J：為三維重建圖像

圖1 腹部CT檢查，左腎下極前方實(shí)性腫塊，大小55 mm×51 mm×92 mm，與腎實(shí)質(zhì)分界欠清，平掃腫塊密度不均勻，CT值約37 HU，內(nèi)見小片狀低密度區(qū)及數(shù)個(gè)斑點(diǎn)狀鈣化影散在分布；增強(qiáng)掃描腫塊呈不均勻輕度強(qiáng)化，雙期增強(qiáng)掃描呈漸進(jìn)性強(qiáng)化，皮質(zhì)期腫塊CT值約56 HU，髓質(zhì)期腫塊CT值約74 HU，強(qiáng)化程度始終明顯低于鄰近正常腎實(shí)質(zhì)

討 論

后腎腺瘤約占成人腎臟上皮源性腫瘤的0.2%[2-3]，最先由Brisigotti等[4]于1992年提出并命名。2004年世界衛(wèi)生組織腎臟腫瘤病理組織學(xué)分類標(biāo)準(zhǔn)中將后腎腫瘤分為后腎腺瘤、后腎纖維腺瘤、后腎間質(zhì)瘤，后腎腺瘤是后腎腫瘤家族中最常發(fā)生、預(yù)后最好的類型。后腎腺瘤可發(fā)生于兒童或成人，多數(shù)發(fā)病年齡為50～60歲，男女比例約1∶2，多為單側(cè)單病灶。后腎腺瘤生物學(xué)行為常為良性，生長緩慢，多為偶然發(fā)現(xiàn)，無明顯臨床癥狀[3]，實(shí)驗(yàn)室檢查大多無異常，文獻(xiàn)報(bào)道10%～12%的患者可能出現(xiàn)紅細(xì)胞增多癥表現(xiàn)[5]。雖然有個(gè)別報(bào)道其可轉(zhuǎn)移至淋巴結(jié)或骨[6-9]，但后腎腺瘤被普遍認(rèn)為是一種良性腫瘤，有良好預(yù)后，部分病例可行保留腎單位腎部分切除術(shù)成功切除腫瘤[1,10-11]，為該類腫瘤的首選術(shù)式。然而，由于目前報(bào)道的后腎腺瘤病例不足200例，臨床工作中對其缺乏足夠的理解，后腎腺瘤容易被誤診為腎惡性腫瘤，特別是最常見的腎細(xì)胞癌。為了避免由于誤診而施行不必要的根治性腎切除手術(shù)，術(shù)前正確診斷變得愈加重要。CT檢查對腎腫瘤的鑒別診斷有一定幫助。

我們以“腎腫瘤，腺瘤”為檢索詞通過萬方醫(yī)學(xué)數(shù)據(jù)庫對中文文獻(xiàn)進(jìn)行檢索，以“Metanephric adenoma”為檢索詞通過PubMed數(shù)據(jù)庫進(jìn)行檢索，檢索時(shí)間截止至2016年8月，可見多篇與后腎腺瘤有關(guān)的中外文文獻(xiàn)，多為個(gè)案報(bào)道，國外文獻(xiàn)報(bào)道過的病例約100多例，其中兒童占20%[12]，描述后腎腺瘤的CT影像表現(xiàn)的文章8篇。國內(nèi)文獻(xiàn)報(bào)道不超過100例，國內(nèi)單中心報(bào)道例數(shù)最多的為荊宏偉等[13]報(bào)道的11例，詳細(xì)描述后腎腺瘤的CT影像表現(xiàn)的文章僅有1篇。馬瑩等[14]回顧分析5例后腎腺瘤患者，認(rèn)為后腎腺瘤的CT影像特點(diǎn)為平掃期呈稍低或稍高密度，可見囊變及鈣化，邊界清楚，增強(qiáng)掃描呈輕中度強(qiáng)化，如患者為女性并伴有紅細(xì)胞增多癥時(shí)，應(yīng)高度懷疑后腎腺瘤。國外文獻(xiàn)報(bào)道，典型的CT影像表現(xiàn)為單個(gè)的圓形或卵圓形實(shí)性腫物，邊界清楚，位于腎實(shí)質(zhì)內(nèi)，部分外突于腎輪廓外[5,15-20]。可見囊性成分、壞死灶、出血灶或鈣化灶[15-17]。在CT平掃時(shí)，與鄰近正常腎實(shí)質(zhì)比較，后腎腺瘤可表現(xiàn)為稍高密度、等密度或稍低密度[16,18-19]，密度多不均勻。CT增強(qiáng)影像表現(xiàn)為密度不均勻腫物呈漸進(jìn)性輕度強(qiáng)化[5,12]，延遲期腫物密度明顯低于鄰近正常腎實(shí)質(zhì)[15-16]，可見腫物內(nèi)部無增強(qiáng)區(qū)，為出血灶或壞死灶的特征表現(xiàn)。從CT增強(qiáng)表現(xiàn)來看，后腎腺瘤為乏血供腫瘤。本例患者的CT影像表現(xiàn)除了邊界不清以外，符合上述后腎腺瘤的CT影像表現(xiàn)。Zhu等[16]報(bào)道8例后腎腺瘤患者，均表現(xiàn)為邊界不清。因此，腫物的邊界是否清楚不應(yīng)作為診斷后腎腺瘤的CT影像特征。

在臨床實(shí)踐中，后腎腺瘤應(yīng)與腎細(xì)胞癌，特別是腎透明細(xì)胞癌、嫌色細(xì)胞癌、乳頭狀腎細(xì)胞癌相鑒別。腎透明細(xì)胞癌是最常見的腎細(xì)胞癌，更多可能會(huì)伴有囊性、出血或壞死成分[21]，是富血供腫瘤，通過增強(qiáng)CT檢查易于診斷，CT增強(qiáng)通常表現(xiàn)為不均勻強(qiáng)化，皮髓質(zhì)期強(qiáng)化顯著高于正常腎實(shí)質(zhì)[22]，排泄期強(qiáng)化快速減退。然而，后腎腺瘤與腎嫌色細(xì)胞癌、乳頭狀腎細(xì)胞癌的鑒別十分困難，后二者均為乏血供腫瘤。本例CT診斷考慮為腎嫌色細(xì)胞癌，主要是因?yàn)楹竽I腺瘤和腎嫌色細(xì)胞癌有相同的CT強(qiáng)化特征，均為持續(xù)漸進(jìn)的輕度強(qiáng)化。但腎嫌色細(xì)胞癌也有其特征性的CT表現(xiàn)，如極少伴有囊性、出血或壞死成分，常見為平掃時(shí)的均勻密度和增強(qiáng)時(shí)的均勻強(qiáng)化[23]，有時(shí)呈輪輻樣強(qiáng)化[24]。然而乳頭狀腎細(xì)胞癌則難與后腎腺瘤相鑒別，二者同樣表現(xiàn)為乏血供、持續(xù)漸進(jìn)的輕中度強(qiáng)化[23]，需要通過術(shù)前細(xì)針抽吸穿刺活檢或術(shù)中冷凍病理檢查鑒別[25]。

對于兒童患者，后腎腺瘤需與腎母細(xì)胞瘤(Wilms瘤)相鑒別。后者的平均發(fā)病年齡為3歲，90%在6歲以內(nèi)，而后腎腺瘤的中位發(fā)病年齡為48.6歲。Wilms瘤通常體積巨大，內(nèi)部密度不均勻，常伴出血、壞死、脂肪或鈣化[26]，常見淋巴結(jié)轉(zhuǎn)移，囊性變并不少見，可為雙側(cè)發(fā)病，并可因腫瘤巨大而壓迫鄰近腎實(shí)質(zhì)，只有9%的Wilms瘤伴有鈣化，據(jù)此可鑒別二者。

總之，后腎腺瘤是罕見的良性腎臟上皮源性腫瘤。后腎腺瘤的CT影像特征缺乏特異性，使其難與其他乏血供腎腫瘤相鑒別，特別是腎嫌色細(xì)胞癌和乳頭狀腎細(xì)胞癌。術(shù)前的準(zhǔn)確診斷對選擇合適的臨床治療策略十分重要，可行術(shù)前或術(shù)中的病理檢查鑒別。其最終診斷需依靠組織細(xì)胞學(xué)檢查。

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(本文編輯：熊鈺芬)

CT imaging features of metanephric adenoma: a case report and review of the literatures

HUANGJian-hua*,MAIYuan,ZHONGYu-xiang,LIUZai-yi,PUXiao-yong,XUZhan-ping.

*DepartmentofUrology,FoshanHospitalofTraditionalChineseMedicine,Foshan528000,ChinaCorrespondingauthor：XUZhan-ping,E-mail:xuzhanping2004@163.com

Objective To improve the diagnostic level of metanephric adenoma (MA). Methods Clinical data of 1 case of MA was analyzed retrospectively. The patient underwent CT examination and was diagnosed as chromophobe renal cell carcinoma, then underwent laparoscopic partial nephrectomy. The final pathological findings were in accordance with MA. Results CT confirmed the presence of a solid mass in the lower pole of the left kidney. On unenhanced CT scan the mass was poorly-defined. The density of the mass was heterogeneous and slightly lower than that of the adjacent normal renal parenchyma. The mass was characterized by a small sheet of necrotic area with low density and multiple small nodules of calcification with high density in its interior. On contrast-enhanced CT scan, the mass showed a pattern of obviously heterogeneous enhancement and during the dual-phase contrast-enhanced CT scan the enhancement was slow and prolonged. The degree of enhancement was significantly lower than that of adjacent normal renal parenchyma. The final pathological findings were in accordance with MA. The patient recovered well, and there was no recurrence after 8 months of follow-up. Conclusions MA is an extremely rare and benign renal neoplasm originating in the epithelial cells of the kidney. The CT imaging features of MA have certain specificity, but it is hard to differentiate MA from other hypovascular renal tumors, especially of chromophobe renal cell carcinoma and papillary renal cell carcinoma. Accurate diagnosis is important for selecting the most appropriate clinical treatment strategy. Preoperative or intraoperative pathological examination may be recommended for the diagnosis of MA.

Kidney neoplasms; Metanephric adenoma; Diagnosis

528000 佛山市中醫(yī)院泌尿外科(黃劍華、麥源、鐘羽翔、徐戰(zhàn)平)；廣東省人民醫(yī)院放射科(劉再毅)；廣東省人民醫(yī)院泌尿外科(蒲小勇)

徐戰(zhàn)平，E-mail:xuzhanping2004@163.com

10.3870/j.issn.1674-4624.2016.05.004

2016-09-08)