Marburger Trent B, Gardner Jerad M, Prieto Victor G, Billings Steven D
Department of Anatomic Pathology, Cleveland Clinic, Cleveland, OH, USA.
J Cutan Pathol. 2012 Nov;39(11):987-95. doi: 10.1111/cup.12007. Epub 2012 Sep 21.
Rhabdomyosarcoma is a malignant mesenchymal tumor with skeletal muscle differentiation. Primary cutaneous rhabdomyosarcoma is rare. We report a series of 11 cases of primary cutaneous rhabdomyosarcoma.
Cases diagnosed as rhabdomyosarcoma arising in the dermis/subcutis with no identified primary tumor elsewhere were retrospectively reviewed. Follow-up was obtained.
The tumors occurred in five children and six adults. The adult subset consisted of pleomorphic, epithelioid and not otherwise specified (NOS) subtypes while the pediatric subset showed alveolar and embryonal subtypes. All cases showed immunohistochemical staining consistent with the diagnosis of rhabdomyosarcoma. Three adult cases showed immunoreactivity for cytokeratins (one pleomorphic, one epithelioid and one NOS.
Primary cutaneous rhabdomyosarcoma shows a bimodal age distribution and male predominance, correlating with rhabdomyosarcoma in deep soft tissue. Follow-up, available on all patients, showed aggressive behavior in both children and adults. Primary cutaneous rhabdomyosarcoma should be considered in the differential diagnosis of tumors with abundant eosinophilic cytoplasm and those with "small round blue cell" morphology. Desmin, myogenin and MYOD1 are a trio of markers with high sensitivity and specificity for primary cutaneous rhabdomyosarcoma. Cytokeratin immunoreactivity in primary cutaneous rhabdomyosarcoma represents a potential diagnostic pitfall in the differential diagnosis with sarcomatoid carcinoma.
横纹肌肉瘤是一种具有骨骼肌分化的恶性间叶性肿瘤。原发性皮肤横纹肌肉瘤罕见。我们报告了一组11例原发性皮肤横纹肌肉瘤病例。
回顾性分析诊断为起源于真皮/皮下组织且未发现其他原发肿瘤的横纹肌肉瘤病例，并进行随访。
肿瘤发生于5名儿童和6名成人。成人组包括多形性、上皮样和未另作特殊说明（NOS）亚型，而儿童组表现为肺泡型和胚胎型亚型。所有病例的免疫组化染色均符合横纹肌肉瘤的诊断。3例成人病例显示细胞角蛋白免疫反应阳性（1例多形性、1例上皮样和1例NOS）。
原发性皮肤横纹肌肉瘤呈现双峰年龄分布且男性居多，与深部软组织横纹肌肉瘤相关。对所有患者的随访显示，儿童和成人病例均具有侵袭性。在鉴别诊断具有丰富嗜酸性细胞质的肿瘤和具有“小圆蓝细胞”形态的肿瘤时，应考虑原发性皮肤横纹肌肉瘤。结蛋白、肌细胞生成素和MYOD1是对原发性皮肤横纹肌肉瘤具有高敏感性和特异性的一组标志物。原发性皮肤横纹肌肉瘤中的细胞角蛋白免疫反应性在与肉瘤样癌的鉴别诊断中代表一个潜在的诊断陷阱。
