Kelley Justin T, Amoth Haley M, Lopez-Hisijos Nicolas, Hrycaj Steven, Valdez Riccardo, Rottmann Douglas
Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN.
Department of Pathology, Michigan Medicine, University of Michigan, Ann Arbor, MI.
Appl Immunohistochem Mol Morphol. 2025 Mar 1;33(2):103-110. doi: 10.1097/PAI.0000000000001241. Epub 2025 Jan 9.
Follicular dendritic cell sarcoma (FDCS) is a rare neoplasm requiring a high index of suspicion, especially on small biopsies. Smooth muscle myosin heavy chain (SMMHC) is a common immunohistochemical (IHC) stain that has been reported to mark normal nodal follicular dendritic cells (FDCs). We hypothesize that SMMHC can be a sensitive marker for FDCS and aim to compare its performance with established markers of FDCS. The archive of a large academic center was searched for cases of FDCS. Clinical features, including age, sex, and site at diagnosis, were reviewed. A hematoxylin and eosin-stained slide was evaluated to assess for morphology and presence of hyaline vascular Castleman disease. The established FDC markers CD21, CD23, fascin, clusterin, and D2-40 were reviewed and compared with SMMHC for all cases. The staining pattern was classified as positive (strong or weak) or negative. Seven unique cases of nodal and extranodal FDCS were collected. SMMHC was positive in most cases (n=5) and performed similarly to established FDC markers, including clusterin, CD21, and CD23 (n=7 each), and fascin and D2-40 (n=4 each). SMMHC was also negative in all 14 examined cases among 5 common differential diagnoses. We demonstrate that the common IHC marker SMMHC has high specificity and similar sensitivity as established FDC markers in nodal and extranodal FDCS, and is useful in the evaluation of common neoplastic mimics.
滤泡树突状细胞肉瘤（FDCS）是一种罕见肿瘤，需要高度怀疑，尤其是在小活检标本中。平滑肌肌球蛋白重链（SMMHC）是一种常见的免疫组织化学（IHC）染色，据报道可标记正常淋巴结滤泡树突状细胞（FDC）。我们假设SMMHC可以作为FDCS的敏感标志物，并旨在将其性能与已确立的FDCS标志物进行比较。在一个大型学术中心的存档中搜索FDCS病例。回顾了临床特征，包括年龄、性别和诊断部位。评估苏木精和伊红染色切片以评估形态以及是否存在透明血管型Castleman病。对所有病例的已确立的FDC标志物CD21、CD23、fascin、clusterin和D2-40进行回顾，并与SMMHC进行比较。染色模式分为阳性（强或弱）或阴性。收集了7例独特的淋巴结和结外FDCS病例。大多数病例（n=5）中SMMHC呈阳性，其表现与已确立的FDC标志物相似，包括clusterin、CD21和CD23（各n=7），以及fascin和D2-40（各n=4）。在5种常见鉴别诊断的所有14例检查病例中，SMMHC也均为阴性。我们证明，常见的免疫组织化学标志物SMMHC在淋巴结和结外FDCS中具有高特异性，且与已确立的FDC标志物具有相似的敏感性，并且在评估常见的肿瘤模仿物方面很有用。
