Department of Pathology, Vancouver General Hospital and University of British Columbia, Vancouver, British Columbia V5Z1M9, Canada.
Hum Pathol. 2011 Nov;42(11):1804-9. doi: 10.1016/j.humpath.2011.01.023. Epub 2011 Jun 11.
Low-grade fibromyxoid sarcoma was first described more than 20 years ago. Subsequently, it was discovered to carry the recurrent chromosomal translocation t(7;16)(q33;p11) encoding a FUS-CREB3L2 fusion oncoprotein. Molecular tests for this pathognomonic gene fusion can confirm the identity of histologic variants (such as hyalinizing spindle cell tumor with giant rosettes) and suggest that some cases of sclerosing epithelioid fibrosarcoma may represent a high-grade version of this entity. We present a case of an ossifying tumor of the perineum that required an open biopsy and fluorescent in situ hybridization testing for FUS and CREB3L2 for diagnosis as a variant of low-grade fibromyxoid sarcoma. Subsequent excision revealed characteristic areas with collagen rosettes as well as foci of heterotopic ossification. Significant ossification, which is well documented in entities such as synovial sarcoma, ossifying fibromyxoid tumor, and extraskeletal osteosarcoma, has not been reported previously in low-grade fibromyxoid sarcoma. This case demonstrates the value of having a distinctive confirmatory molecular pathology test for diagnosis and expands our knowledge of the histologic variants possible in low-grade fibromyxoid sarcoma.
低度纤维黏液样肉瘤在 20 多年前首次被描述。随后发现其携带反复出现的染色体易位 t(7;16)(q33;p11)，编码 FUS-CREB3L2 融合致癌蛋白。针对这种特征性基因融合的分子检测可确认组织学变异型（如伴有巨玫瑰花结的玻璃样化梭形细胞肿瘤），并提示某些硬化性上皮样纤维肉瘤病例可能代表该实体的高级别版本。我们报告了一例会阴部骨化性肿瘤的病例，该肿瘤需要进行开放性活组织检查，并进行 FUS 和 CREB3L2 的荧光原位杂交检测，以诊断为低度纤维黏液样肉瘤的变异型。随后的切除显示出具有胶原玫瑰花结的特征区域以及异位骨化灶。在滑膜肉瘤、骨化性纤维黏液瘤和骨外骨肉瘤等实体瘤中已有大量骨化的明确报道，而在低度纤维黏液样肉瘤中尚未有过相关报道。该病例证明了具有独特的确认性分子病理学检测在诊断中的价值，并扩展了我们对低度纤维黏液样肉瘤中可能存在的组织学变异型的认识。
