- 期刊
Perivascular Epithelioid Cell Tumor of the Rectum: Differential Diagnosis of a Rare Case
直腸之血管旁類上皮細胞瘤：一罕見病例及其鑑別診斷
摘要
Perivascular epithelioid cell tumors are a group of mesenchymal tumors that typically occur in soft tissue. These tumors have been reported in various organs but rarely in the gastrointestinal tract. Most of them are considered low-grade malignant tumors; however, some cases of high-grade malignancy have been described. We report a case with long-term follow-up of a rectal tumor in a 57-year-old woman presenting with bloody stool. Colonoscopic examination revealed a 1.5-cm submucosal tumor in the rectum, and the patient underwent endoscopic snaring polypectomy. Tumor histology showed large polygonal cells with clear to slightly eosinophilic cytoplasm arranged in an organoid pattern. Immunohistochemical studies of the tumor cells revealed positive reactivity for HMB-45 and negative staining for smooth muscle actin, desmin, cytokeratin, synaptophysin, chromogranin A, CD34, CD117, S100 proteins, and TFE3. Thus, a colorectal perivascular epithelioid cell tumor was diagnosed. A definite diagnosis of a gastrointestinal perivascular epithelioid cell tumor is difficult because of its rarity and variable morphology. The biological characteristics, clinical behaviors, and definitive treatment of the tumors are not completely understood owing to limited case reports and studies. The differential diagnosis, malignant potential, and clinical expression and treatment of these tumors are discussed after a review of the literature. Patients should be carefully followed owing to the malignant potential of these tumors.
並列摘要
血管旁類上皮細胞瘤 (perivascular epithelioid cell tumor) 是一群具有肌細胞及黑色素細胞分化 (myomelanocytic) 的特殊細胞所形成的罕見腫瘤。此類腫瘤多發生於軟組織，世界衛生組織於2002 年將之列於軟組織腫瘤的正式分類之一。之後開始有一些病例被報告發生於腎臟、肝臟、子宮等臟器中，但發生於腸胃道的病例則少之又少，近年來只有一些零星病例報告，因此尚未列入世界衛生組織之腸胃道腫瘤分類中。此類腫瘤的臨床表現差異極大，從良性到高惡性轉移及致死病例都有可能。由於病例稀少，此類腫瘤尚無法規劃出標準治療方針與準確地預測病人臨床表現。也因為此腫瘤罕見，導致確切診斷警覺度低，使鑑別診斷困難，常需經歷一系列病理及免疫化學染色檢查，方能獲得正確診斷。而其臨床處置方法與預後和腫瘤的病理表現息息相關，因此正確的診斷與詳細的病理表現描述，對臨床醫師決定如何給予病人術後的處置與追蹤是很重要的。我們報告這例位於直腸的病例，起初被臆測為類癌 (carcinoid tumor) 或腸胃基質腫瘤(gastrointestinal stromal tumor)，經過病理切片及免疫染色多種抗體檢查後確診是血管旁類上皮細胞瘤。我們報告這位罕見病例，並收集發生於腸胃道之此類腫瘤的相關文獻，使讀者能進一步了解腸胃道血管旁類上皮細胞瘤的特性，以期增加診斷率及給予病人更適當的處置與追蹤。