van Wyk Abraham Christoffel, van Zyl Hennie, Rigby Jonathan
Division of Anatomical Pathology, National Health Laboratory Service, Faculty of Medicine and Health Sciences, Tygerberg Hospital, Stellenbosch University, Cape Town, South Africa.
Department of Surgery, Karl Bremer Hospital, Cape Town, South Africa.
Diagn Pathol. 2018 Feb 20;13(1):16. doi: 10.1186/s13000-018-0694-z.
Colorectal perineuriomas are uncommon benign mucosal-based proliferations of mesenchymal cells that express perineurial markers, often associated with colonic crypts displaying a serrated/hyperplastic architecture. The vast majority of cases arise distal to the splenic flexure and have been described as sessile polyps. Using molecular analysis, BRAF mutations have been demonstrated in the serrated crypt epithelium. We report a new case of perineurioma presenting as a pedunculated polyp in the transverse colon, with prominent hemosiderin deposits in the uninvolved lamina propria that separated the perineurial proliferation from the surface epithelium, a previously unreported histological finding. By using immunohistochemistry, we demonstrated the presence of BRAF V600E mutated protein in the serrated crypt epithelium. In addition, a review of the literature on colorectal perineurioma is provided.
A 5 mm pedunculated polyp was removed from the transverse colon of a 42 year old man who presented with epigastric pain, weight loss and rectal bleeding. A proliferation of uniform plump spindled cells expanded the lamina propria and separated serrated colonic crypts. The epithelial component closely resembled microvesicular hyperplastic polyp. Immunohistochemical stains for epithelial membrane antigen (EMA), glucose transporter 1 (GLUT1) and collagen IV were positive in the stromal proliferation. A mutation-specific monoclonal antibody directed against BRAF V600E showed positive cytoplasmic staining in the serrated crypt epithelium but not in the perineurial proliferation. Conspicuous hemosiderin deposition was seen in the inflamed lamina propria between the perineurial proliferation and the surface epithelium.
Although the majority of colorectal perineuriomas occur in the sigmoid colon and rectum and are described as sessile polyps, colorectal perineurioma can present as a pedunculated polyp proximal to the splenic flexure as described in this case. Conspicuous hemosiderin deposition can be seen in the superficial lamina propria. BRAF mutations are limited to the serrated crypt epithelium.
结直肠束状神经瘤是一种罕见的以黏膜为基础的间充质细胞良性增殖性病变，表达束状神经标记物，常与呈现锯齿状/增生性结构的结肠隐窝相关。绝大多数病例发生在脾曲远端，表现为无蒂息肉。通过分子分析，已证实在锯齿状隐窝上皮中存在BRAF突变。我们报告了1例新的束状神经瘤，表现为横结肠带蒂息肉，在未受累的固有层中有明显的含铁血黄素沉积，该固有层将束状神经增生与表面上皮分隔开，这是一个以前未报道过的组织学发现。通过免疫组织化学，我们证实在锯齿状隐窝上皮中存在BRAF V600E突变蛋白。此外，还提供了结直肠束状神经瘤的文献综述。
从一名42岁男性的横结肠切除了一个5毫米带蒂息肉，该患者有上腹部疼痛、体重减轻和直肠出血症状。均匀饱满的梭形细胞增生使固有层增宽，并分隔了锯齿状结肠隐窝。上皮成分与微泡状增生性息肉非常相似。上皮膜抗原（EMA）、葡萄糖转运蛋白1（GLUT1）和IV型胶原的免疫组织化学染色在间质增生中呈阳性。针对BRAF V600E的突变特异性单克隆抗体在锯齿状隐窝上皮中显示出阳性细胞质染色，但在束状神经增生中未显示。在束状神经增生与表面上皮之间的炎症固有层中可见明显的含铁血黄素沉积。
尽管大多数结直肠束状神经瘤发生在乙状结肠和直肠，表现为无蒂息肉，但结直肠束状神经瘤也可如本例所述，表现为脾曲近端的带蒂息肉。在浅表固有层中可见明显的含铁血黄素沉积。BRAF突变仅限于锯齿状隐窝上皮。
