Abstract：
Myoepithelial tumors of the soft tissue and bone occurring in patients 21 years of age and younger are rare, and their clinicopathologic features remain incompletely understood. We studied a well-characterized series of 40 such tumors. Cases were retrieved from our archives for the period 2009-2022 and re-reviewed. Available immunohistochemical and molecular genetic data was collected. Clinical information including available follow-up was obtained. The tumors occurred in 18 males and 22 females, ranging from 3 months to 21 years of age (median 11.5 years), and involved a wide variety of soft tissue (n = 36) and bone (n = 4) locations. Histologically benign myoepithelial tumors tended to occur in adolescents (median age 14.5 years; range 5-21 years), whereas myoepithelial carcinomas occurred in younger patients (median age 8.5 years; range 3 months-20 years). Microscopically, the tumors showed a complex admixture of epithelioid, plasmacytoid and spindled cells in a variably hyalinized, myxoid, chondroid or chondromyxoid background. Small subsets of histologically malignant tumors had rhabdoid or \"round cell\" features. Immunohistochemistry showed 35/40 (88%) cases to be positive with at least one keratin antibody. The 5 keratin-negative tumors were uniformly positive for S100 protein and/or SOX10 and expressed EMA (4 cases) and/or p63 (3 cases). EMA, SMA and GFAP were positive in 21/25 (84%), 13/21 (62%), and 8/21 (38%) tumors, respectively. SMARCB1 and SMARCA4 expression was retained in 29/31 (94%) and 22/22 (100%) of cases, respectively. FISH for EWSR1 gene rearrangement was positive in 6/18 (33%) tested cases. Two EWSR1-negative tumors were also FUS-negative. NGS identified EWSR1::POU5F1, FUS::KLF17, and BRD4::CITED1 gene fusions in 3 tested cases. Clinical follow-up (22 patients; median 23 months; range 1-119 months) showed 3 patients with local recurrences and 5 with distant metastases (lymph nodes, lung, and brain). Three patients died of disease, 3 were alive with recurrent or unresectable disease, and 16 were disease-free. Adverse clinical outcomes were seen only in patients with malignant tumors. We conclude that myoepithelial neoplasms of soft tissue and bone are over-repesented in patients ≤21 years of age, more often histologically malignant, and potentially lethal. Histologic evaluation appears to reliably predict the behavior of these rare tumors.
摘要：
发生在21岁及以下患者的软组织和骨的肌上皮肿瘤是罕见的，其临床病理特征仍未完全了解。我们研究了一系列特征明确的40种此类肿瘤。从我们的档案中检索了2009-2022年期间的病例，并进行了重新审查。收集可用的免疫组织化学和分子遗传学数据。获得了包括可用随访在内的临床信息。肿瘤发生在18名男性和22名女性中，年龄从3个月到21岁不等(中位数11.5岁)，涉及多种软组织（n=36）和骨骼（n=4）位置。组织学上良性肌上皮肿瘤往往发生在青少年中（中位年龄14.5岁；范围5-21岁），而肌上皮癌发生在年轻患者(中位年龄8.5岁;范围3个月-20岁).微观上,肿瘤表现出复杂的上皮样混合，浆细胞样细胞和纺锤体细胞在一个可变的透明，粘液样，软骨样或软骨粘液样背景。组织学恶性肿瘤的小亚群具有横纹肌样或“圆形细胞”特征。免疫组织化学显示35/40（88％）例至少一种角蛋白抗体阳性。5例角蛋白阴性肿瘤均为S100蛋白和/或SOX10阳性，并表达EMA（4例）和/或p63（3例）。EMA,SMA和GFAP在21/25(84%)呈阳性，13/21（62%），8/21（38%）肿瘤，分别。SMARCB1和SMARCA4的表达在29/31（94%）和22/22（100%）的病例中得以保留，分别。在6/18（33％）的测试病例中，EWSR1基因重排的FISH呈阳性。两个EWSR1阴性肿瘤也是FUS阴性。NGS在3例测试病例中鉴定出EWSR1::POU5F1、FUS::KLF17和BRD4::CITED1基因融合体。临床随访（22例；中位数23个月；范围1-119个月）显示3例患者局部复发，5例远处转移（淋巴结，肺，和大脑）。三个病人死于疾病,3人患有复发性或不可切除的疾病，16人无病。仅在恶性肿瘤患者中出现不良临床结局。我们得出的结论是，在年龄<21岁的患者中，软组织和骨骼的肌上皮肿瘤过度增生，更常见的是组织学上的恶性，并可能致命。组织学评估似乎可以可靠地预测这些罕见肿瘤的行为。
