Yang Sara H, McCalmont Timothy H, Ahn George G, Yeh Iwei
Departments of *Pathology, and †Dermatology, University of California, San Francisco, CA.
Am J Dermatopathol. 2014 May;36(5):e93-6. doi: 10.1097/01.dad.0000441941.83273.c5.
A 7-year-old boy was presented with a long-standing slowly growing mass of the left supraorbital area. A biopsy specimen revealed a bland spindle cell proliferation with scattered polygonal cells with acidophilic cytoplasm and cross-striations. Our differential diagnosis included rhabdomyoma of fetal type, leiomyoma with trapping of regenerating skeletal muscle elements, and rhabdomyomatous mesenchymal hamartoma of the skin. Immunohistochemistry demonstrated strong positivity of myoglobin and desmin as well as negativity of caldesmon, suggesting skeletal muscle lineage. The excisional specimen confirmed our diagnosis of cutaneous fetal rhabdomyoma of intermediate type. Additional immunostaining performed on the excisional specimen showed strong Wilms Tumor 1 but only a very faint and focal p63 expression.
一名7岁男孩左侧眶上区长有一个长期缓慢生长的肿块。活检标本显示为温和的梭形细胞增生，散在分布着具有嗜酸性细胞质和横纹的多边形细胞。我们的鉴别诊断包括胎儿型横纹肌瘤、伴有再生骨骼肌成分陷入的平滑肌瘤以及皮肤横纹肌间叶性错构瘤。免疫组织化学显示肌红蛋白和结蛋白呈强阳性，而钙调蛋白呈阴性，提示为骨骼肌谱系。切除标本证实我们诊断为中间型皮肤胎儿横纹肌瘤。对切除标本进行的额外免疫染色显示Wilms肿瘤1呈强阳性，但p63仅呈非常微弱的局灶性表达。
