He Xue, Chen Nannan, Lin Li, Wang Congyang, Wang Yan
Department of Pathology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China.
J Int Med Res. 2017 Jun;45(3):1273-1278. doi: 10.1177/0300060517706577. Epub 2017 May 28.
Extragastrointestinal stromal tumors (EGISTs) are rare tumors that arise outside the digestive tract. We report a case of an EGIST arising in the subcutaneous tissue of the abdominal wall, which at this site can often be misdiagnosed as dermatofibrosarcoma protuberans. The tumor was surgically resected from a 72-year-old male Chinese Han patient, and pathological examination revealed spindle-shaped tumor cells with eosinophilic cytoplasm and an oval nucleus. Immunohistochemically, the tumor cells showed strong cytoplasmic positivity for CD34, c-KIT (CD117), and DOG1. Tests for activating mutations of GISTs showed that the tumor cells carried an in-frame deletion (NP_000213.1:p.Lys550_Gln556del) in exon 11 of c-KIT (CD117). Thus, an EGIST should be considered in patients with abdominal subcutaneous tumors with an epithelioid, spindle-shaped, or mixed morphology. Immunohistochemistry of c-KIT (CD117) and DOG1 and genetic testing for activating mutations are recommended to aid in the differential diagnosis of subcutaneous tumors. In short, although EGISTs are rare in the abdominal subcutaneous tissue, pathologists must be aware of their possibility.
胃肠道外间质瘤（EGISTs）是起源于消化道外的罕见肿瘤。我们报告一例发生于腹壁皮下组织的EGIST，在此部位它常被误诊为隆突性皮肤纤维肉瘤。该肿瘤来自一名72岁中国汉族男性患者，经手术切除，病理检查显示肿瘤细胞呈梭形，胞质嗜酸性，核呈椭圆形。免疫组化检查显示，肿瘤细胞的CD34、c-KIT（CD117）和DOG1呈强细胞质阳性。胃肠道间质瘤激活突变检测显示，肿瘤细胞的c-KIT（CD117）第11外显子存在框内缺失（NP_000213.1:p.Lys550_Gln556del）。因此，对于具有上皮样、梭形或混合形态的腹部皮下肿瘤患者，应考虑EGIST的可能。建议进行c-KIT（CD117）和DOG1免疫组化以及激活突变基因检测，以协助皮下肿瘤的鉴别诊断。简而言之，尽管EGIST在腹部皮下组织中罕见，但病理学家必须意识到其可能性。
