Donati Michele, Kastnerova Liubov, Ptakova Nikola, Michal Michal, Kazakov Dmitry V
Department of Pathology, University Hospital Campus Bio-Medico, Rome, Italy.
Sikl's Department of Pathology, Medical Faculty in Pilsen, Charles University in Prague, Pilsen, Czech Republic.
Am J Dermatopathol. 2020 Mar;42(3):204-207. doi: 10.1097/DAD.0000000000001502.
We report a case of a polypoid atypical Spitz tumor with a prominent fibrosclerotic stromal component, harboring a CLIP2-BRAF fusion, which has hitherto been not reported in melanocytic lesions. The neoplasm occurred in a 78-year-old male patient and appeared microscopically as a predominantly dermal, barely symmetrical, polypoid lesion composed mainly of epithelioid cells showing moderate degree of nuclear pleomorphism with ample amphophilic cytoplasm arranged in nests, fascicles, or single units. The mitotic rate was 2/mm, and the mitoses were confined to the upper portion of the lesion. The Breslow thickness was 2.3 mm. The stroma contained conspicuous plumped fibroblasts and thickened collagen bundles associated with dilated medium-sized vessels. Focally, sclerotic areas were found. A moderately dense, lymphocyte-predominant inflammatory infiltrate scattered through the whole lesion was seen. Despite strong nuclear and cytoplasmic positivity of p16, FISH revealed homozygous loss in locus 9p21. A CLIP2-BRAF fusion was found by next-generation sequencing. No other genetic alterations including a TERT-promoter mutation was found. The patient is disease-free without recurrence or evidence of metastatic disease after 5 years and 2 months of follow-up.
我们报告了一例具有显著纤维硬化性间质成分的息肉状非典型斯皮茨瘤病例，该肿瘤存在CLIP2 - BRAF融合基因，这在黑素细胞性病变中尚未见报道。该肿瘤发生于一名78岁男性患者，显微镜下表现为主要位于真皮层、几乎不对称的息肉状病变，主要由上皮样细胞组成，这些细胞显示中度核异型性，具有丰富的嗜双色性细胞质，呈巢状、束状或单个排列。有丝分裂率为2/平方毫米，且有丝分裂局限于病变上部。Breslow厚度为2.3毫米。间质中可见明显肿胀的成纤维细胞和增厚的胶原束，伴有扩张的中等大小血管。局部可见硬化区域。可见中等密度、以淋巴细胞为主的炎性浸润散在分布于整个病变。尽管p16在细胞核和细胞质中呈强阳性，但荧光原位杂交显示9p21位点纯合缺失。通过二代测序发现了CLIP2 - BRAF融合基因。未发现包括TERT启动子突变在内的其他基因改变。经过5年零2个月的随访，患者无病，无复发或转移疾病证据。
