Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
Am J Surg Pathol. 2012 Aug;36(8):1119-28. doi: 10.1097/PAS.0b013e31825d532d.
Consistent rearrangements of chromosomes 13q and 16q have been identified in spindle cell and pleomorphic lipomas by cytogenetics. Mammary-type myofibroblastoma and cellular angiofibroma show overlapping histologic features and similar chromosomal losses, suggesting a possible relationship among these tumor types. The tumor suppressor gene RB1, encoding the retinoblastoma (Rb) protein, is located at 13q14, within a minimally deleted region in spindle cell lipoma. The purpose of this study was to examine expression of Rb by immunohistochemistry in spindle cell lipoma, pleomorphic lipoma, mammary-type myofibroblastoma, and cellular angiofibroma, and in histologic mimics, to determine its potential diagnostic utility. Whole-tissue sections of 194 tumors were evaluated: 18 spindle cell lipomas, 20 pleomorphic lipomas, 19 mammary-type myofibroblastomas, 16 cellular angiofibromas, 22 conventional lipomas (8 intramuscular), 18 atypical lipomatous tumors (all positive for MDM2 and CDK4), 19 solitary fibrous tumors, 19 myxoid liposarcomas, 14 hibernomas, 11 deep (aggressive) angiomyxomas, 9 angiomyofibroblastomas, and 9 vulval fibroepithelial stromal polyps. Immunohistochemistry was performed after pressure cooker antigen retrieval using a mouse anti-Rb monoclonal antibody. Nuclear staining for Rb was scored as "intact" or "deficient." Rb expression was deficient in all spindle cell lipomas, pleomorphic lipomas, and cellular angiofibromas and in 17 (89%) mammary-type myofibroblastomas. Rb staining was sometimes difficult to interpret in cellular angiofibromas with reactive stromal changes. Rb was also deficient in 2 (9%) conventional lipomas. Rb expression was intact in all other tumor types evaluated. In summary, of the soft tissue tumors associated with 13q deletions, all spindle cell lipomas, pleomorphic lipomas, and cellular angiofibromas and most mammary-type myofibroblastomas show loss of Rb expression. Rb expression is intact in histologic mimics. These findings reinforce the pathogenetic relationship among this group of tumors and demonstrate the potential diagnostic utility of immunohistochemistry for Rb.
染色体 13q 和 16q 的一致性重排已通过细胞遗传学在纺锤形细胞和多形性脂肪瘤中得到鉴定。乳腺型肌纤维母细胞瘤和细胞血管纤维瘤具有重叠的组织学特征和相似的染色体缺失，表明这些肿瘤类型之间可能存在关系。肿瘤抑制基因 RB1 位于 13q14，编码视网膜母细胞瘤 (Rb) 蛋白，位于纺锤形细胞脂肪瘤中最小缺失区域内。本研究的目的是通过免疫组织化学检查在纺锤形细胞脂肪瘤、多形性脂肪瘤、乳腺型肌纤维母细胞瘤和细胞血管纤维瘤以及组织学模拟物中检测 Rb 的表达，以确定其潜在的诊断效用。评估了 194 个肿瘤的全组织切片：18 个纺锤形细胞脂肪瘤、20 个多形性脂肪瘤、19 个乳腺型肌纤维母细胞瘤、16 个细胞血管纤维瘤、22 个常规脂肪瘤（8 个位于肌肉内）、18 个非典型脂肪瘤（均为 MDM2 和 CDK4 阳性）、19 个孤立性纤维瘤、19 个黏液样脂肪瘤、14 个冬眠瘤、11 个深部（侵袭性）血管黏液瘤、9 个血管肌纤维母细胞瘤和 9 个外阴纤维上皮性间质息肉。使用小鼠抗 Rb 单克隆抗体进行高压锅抗原修复后进行免疫组织化学染色。Rb 的核染色评分“完整”或“缺失”。所有纺锤形细胞脂肪瘤、多形性脂肪瘤和细胞血管纤维瘤以及 17 个（89%）乳腺型肌纤维母细胞瘤的 Rb 表达均缺失。在伴有反应性基质改变的细胞血管纤维瘤中，Rb 染色有时难以解释。2 个（9%）常规脂肪瘤的 Rb 表达也缺失。在评估的所有其他肿瘤类型中，Rb 表达完整。总之，在与 13q 缺失相关的软组织肿瘤中，所有纺锤形细胞脂肪瘤、多形性脂肪瘤和细胞血管纤维瘤以及大多数乳腺型肌纤维母细胞瘤均显示 Rb 表达缺失。组织学模拟物中的 Rb 表达完整。这些发现强化了这组肿瘤之间的发病机制关系，并证明了免疫组织化学检测 Rb 的潜在诊断效用。
