Nielsen G P, O'Connell J X, Rosenberg A E
James Homer Wright Pathology Laboratories, Massachusetts General Hospital, Harvard Medical School, Boston 02114, USA.
Am J Surg Pathol. 1998 Oct;22(10):1222-7. doi: 10.1097/00000478-199810000-00007.
Intramuscular myxoma (IM) is a benign soft-tissue tumor that presents as a deeply seated mass confined to skeletal muscle. Surgical excision is virtually always curative. Recurrence, even after incomplete resection, is exceptional. Intramuscular myxoma is classically described as hypocellular and hypovascular, and is composed of cytologically bland stellate and bipolar fibroblasts separated by abundant extracellular myxoid matrix. What is underemphasized, however, is that IMs often show areas of increased cellularity and vascularity that can lead to a mistaken diagnosis of sarcoma, especially myxofibrosarcoma, low-grade fibromyxoid sarcoma, and myxoid liposarcoma. In this report, we describe the clinicopathologic features of 51 IMs with special emphasis on those that exhibit these "hypercellular regions." The patients included 35 women and 16 men who ranged in age from 27 to 89 (mean 52) years. The tumors measured from 2 to 15 (average 5.6) cm and all had a gelatinous, lobulated cut surface. Histologically, they all demonstrated classic hypocellular, hypovascular regions. Thirty-eight tumors contained areas of relative increased cellularity that occupied from 10 to 80% of the tumor. These foci had increased numbers of cells, more prominent vascularity, and often increased collagen content. The hypercellular regions were not associated with cytologic atypia of the constituent cells, mitotic activity, or necrosis. Follow-up information was available for 32 patients and ranged from 3 to 108 (average 30) months. No tumor recurred or metastasized. Areas of hypercellularity are common in IMs. Their recognition is important to avoid an erroneous diagnosis of sarcoma.
肌内黏液瘤（IM）是一种良性软组织肿瘤，表现为局限于骨骼肌内的深部肿块。手术切除几乎总能治愈。即使不完全切除后复发也极为罕见。肌内黏液瘤传统上被描述为细胞稀少和血管较少，由细胞学上温和的星状和双极成纤维细胞组成，其间有丰富的细胞外黏液样基质。然而，未被充分强调的是，肌内黏液瘤常显示细胞增多和血管增多区域，这可能导致误诊为肉瘤，尤其是黏液纤维肉瘤、低级别纤维黏液样肉瘤和黏液样脂肪肉瘤。在本报告中，我们描述了51例肌内黏液瘤的临床病理特征，特别强调那些表现出这些“细胞增多区域”的病例。患者包括35名女性和16名男性，年龄在27至89岁（平均52岁）之间。肿瘤大小为2至15厘米（平均5.6厘米），所有肿瘤切面均呈胶冻状、分叶状。组织学上，它们均显示典型的细胞稀少、血管较少区域。38个肿瘤含有相对细胞增多区域，占肿瘤的10%至80%。这些病灶细胞数量增加、血管更明显，且胶原含量常增加。细胞增多区域与组成细胞的细胞学异型性、核分裂活性或坏死无关。32例患者有随访信息，随访时间为3至108个月（平均30个月）。无肿瘤复发或转移。细胞增多区域在肌内黏液瘤中很常见。认识到这一点对于避免肉瘤的错误诊断很重要。
