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性别 | 男 | 年龄 | 31岁 | 临床诊断 | 胃体大弯侧粘膜下占位 |
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一般病史 | 无明显诱因下上腹隐痛。超声内镜:粘膜下见低回声病灶,边界清晰,包膜完整,直径为12.4×10.8mm,提示粘膜下占位。• 腹部CTA:胃体大弯侧胃壁局部增厚,可见结节状等密度灶,大小约1.5×1.3cm,边缘光整,增强动脉期可见明显强化,(平扫CT值约14Hu,动脉期CT值约169Hu,门脉期CT值约128Hu)。 | ||||
标本名称 | 胃体大弯侧粘膜下肿块 | ||||
大体所见 | 结节一枚,大小1.3×1.3×1cm,切面灰红、质中,局部表面覆胃壁,大小3×3×1.5cm,与肿块相连处粘膜局部隆起。 |
Department of Pathology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
Pathological diagnosis of gastrointestinal stromal tumors (GISTs) is based on histological findings and immunohistochemical demonstration of the KIT protein. KIT-negative GISTs account for ∼5% of cases and cause diagnostic difficulties. In the era of imatinib therapy, a correct diagnosis of GISTs is important for therapeutic reasons regardless of KIT expression. Recently, DOG1 has been introduced as an important diagnostic marker with high sensitivity and specificity. In this study, immunohistochemical staining for DOG1 and protein kinase C-θ (PKC-θ) in whole tissue sections, and mutation analyses for KIT and PDGFRA were performed in 26 KIT-negative GISTs. Tissue microarrays of 112 KIT-positive GISTs were used as controls. Overall, 25 KIT-negative GISTs were located in the stomach, and 1 in the rectum. The histological subtype was spindle in 12, epithelioid in 11, and mixed in 3 cases. The expression of DOG1 and PKC-θ was positive in 24 (92%) and in 25 cases (96%), respectively. All 26 KIT-negative GISTs expressed either DOG1 or PKC-θ, and 23 cases (89%) were positive for both makers. PKC-θ was positive in two cases (8%), which lacked both KIT and DOG1 expressions. Mutation analysis showed PDGFRA exon 18 mutation in 15 cases (58%) and KIT exon 11 mutation in 1 case (4%), whereas the remaining 10 cases (39%) were wild type for both KIT and PDGFRA. The expression of DOG1 and PKC-θ showed no significant difference in KIT-negative and KIT-positive GISTs (P=1.000 and P=0.167, respectively). Our findings suggest that both DOG1 and PKC-θ can be used in the diagnosis of KIT-negative GISTs and they show positive staining even in KIT-negative tumors, which are wild type for KIT and PDGFRA on mutation analysis.