Aix Marseille Univ, INSERM, MMG, APHM, CHU Timone, Department of Pathology, Marseille, France.
Institut Bergonié, Department of Pathology, Université de Bordeaux, Talence, Bordeaux, France.
Mod Pathol. 2020 Jul;33(7):1360-1368. doi: 10.1038/s41379-020-0493-4. Epub 2020 Feb 11.
Acral soft tissue tumors are common neoplasms, a subset of which pose a diagnostic challenge. We report 10 cases of a previously unrecognized acral benign soft tissue tumor. These tumors arose on the fingers and toes and involved bone in half of cases. Histologically, the tumors were lobulated and displayed an abundant stroma made of variable fibrous, chondroid and myxoid material reminiscent of cartilaginous or myoepithelial differentiation. Tumor cells harbored small round to reniform nuclei with clear chromatin and inconspicuous nucleoli along with scant eosinophilic cytoplasm. The cells were mostly arranged haphazardly in the stroma but also in small clusters. No mitotic activity was detected. No specific feature was identified in recurrent cases. By immunohistochemistry, the cells consistently stained for CD34 (10/10), ERG (9/10), and SOX9 (7/10). Whole RNA sequencing identified a previously undescribed recurrent in frame THBS1-ADGRF5 gene fusion in all cases. The transcript was confirmed by RT-PCR and was not found in the control group of mimickers including soft tissue chondromas. We propose the name of Acral FibroChondroMyxoid Tumors for this new entity.
肢端软组织肿瘤很常见，其中一些具有诊断挑战性。我们报告了 10 例以前未被识别的肢端良性软组织肿瘤。这些肿瘤发生在手指和脚趾上，半数病例累及骨骼。组织学上，肿瘤呈分叶状，有丰富的间质，由不同的纤维、软骨样和黏液样物质组成，类似于软骨或肌上皮分化。肿瘤细胞具有小而圆形到肾形的核，染色质清晰，核仁不明显，伴有少量嗜酸性细胞质。细胞主要随机排列在基质中，但也呈小簇状排列。在复发病例中没有检测到有丝分裂活动。在复发病例中没有发现特定的特征。通过免疫组织化学染色，所有病例的细胞均持续表达 CD34（10/10）、ERG（9/10）和 SOX9（7/10）。全 RNA 测序在所有病例中均发现了以前未描述的 THBS1-ADGRF5 基因融合。通过 RT-PCR 证实了该转录本，在包括软组织软骨瘤在内的模拟物对照组中未发现该转录本。我们建议将这种新实体命名为肢端纤维软骨黏液瘤。
