Harach H R, Williams E D
Histopathology. 1983 Sep;7(5):739-51. doi: 10.1111/j.1365-2559.1983.tb02286.x.
Riedel's thyroiditis is a rare disease which has in the past been confused with the much commoner fibrous variant of Hashimoto's thyroiditis. We have compared the histological and immunohistochemical characteristics of three cases diagnosed as Riedel's thyroiditis with five cases of the fibrous variant of Hashimoto's thyroiditis. The major distinguishing features on light microscopic study were that Riedel's thyroiditis showed (a) extra-thyroid extension of the fibrous tissue, (b) a phlebitis with distension of the vein lumen by lymphoid or fibrous tissue, and (c) relatively normal surviving thyroid tissue, while in Hashimoto's thyroiditis the fibrous tissue did not extend outside the thyroid, the veins were surrounded by fibrous tissue, but did not show a phlebitis, and all thyroid tissue was affected by the process. These findings confirm those of other workers in suggesting that there is a clear histological distinction between these two processes. The quantitative immunohistochemical studies showed that in the fibrous variant of Hashimoto's thyroiditis, cells containing kappa chains outnumbered lambda chain cells in all cases, the mean ratio of kappa to lambda being very close to that found generally in the circulation, with lambda chain cells forming 36% of all light chain containing cells. In contrast, the mean proportion of lambda chain cells in Riedel's thyroiditis was 71%. In Hashimoto's thyroiditis the dominant plasma cell was, as expected, the IgG containing cell, with IgA cells forming only 15% of all heavy chain cells. In Riedel's thyroiditis IgA containing plasma cells were unusually prominent, forming 47% of all plasma cells present. These findings confirm the separation of the two entities, and demonstrate an unusual pattern of restriction of antibody forming cells in Riedel's thyroiditis. It is possible that IgA plays a role in the pathogenesis of Riedel's thyroiditis.
里德尔甲状腺炎是一种罕见疾病，过去曾与更为常见的桥本甲状腺炎纤维变体相混淆。我们比较了3例诊断为里德尔甲状腺炎的病例与5例桥本甲状腺炎纤维变体病例的组织学和免疫组化特征。光镜研究的主要鉴别特征是，里德尔甲状腺炎表现为：（a）纤维组织向甲状腺外延伸；（b）静脉炎，静脉腔被淋巴组织或纤维组织扩张；（c）相对正常的存活甲状腺组织。而在桥本甲状腺炎中，纤维组织不延伸至甲状腺外，静脉被纤维组织包围，但无静脉炎表现，所有甲状腺组织均受该病变影响。这些发现证实了其他研究者的观点，即这两种病变在组织学上有明显区别。定量免疫组化研究表明，在桥本甲状腺炎纤维变体中，所有病例中含κ链的细胞数量均超过含λ链的细胞，κ链与λ链的平均比例与循环中普遍发现的比例非常接近，λ链细胞占所有含轻链细胞的36%。相比之下，里德尔甲状腺炎中λ链细胞的平均比例为71%。在桥本甲状腺炎中，如预期的那样，占主导地位的浆细胞是含IgG的细胞，IgA细胞仅占所有重链细胞的15%。在里德尔甲状腺炎中，含IgA的浆细胞异常突出，占所有浆细胞的47%。这些发现证实了这两种实体的区分，并证明了里德尔甲状腺炎中抗体形成细胞的一种不寻常的限制模式。IgA可能在里德尔甲状腺炎的发病机制中起作用。
