Endocrine Unit, Department of Medicine, University of Padova School of Medicine, Via Ospedale Civile 105, 35128, Padova, Italy.
J Endocrinol Invest. 2014 Dec;37(12):1175-9. doi: 10.1007/s40618-014-0157-7. Epub 2014 Aug 23.
Graves' disease (GD) is commonly associated with other autoimmune conditions, and there is also a rare but well documented association between GD and thymic hyperplasia (TH). It is hard to say the real frequency of this latter association because most cases remain asymptomatic and are consequently not thoroughly investigated.
We reviewed the literature on GD-related thymus enlargement and found 107 cases published to date. Thymic cancer was only documented in four patients, while the majority of cases were diagnosed as TH. The causative mechanisms behind TH associated with GD have yet to be fully elucidated. Several studies support the hypothesis of a TSH receptor antibody (TRAb) mediating thymic enlargement.
We report on a female GD patient with an incidentally discovered anterior mediastinal mass. Our case is not consistent with the hypothesis of a TRAb-mediated mechanism because the thymus reached its largest volume at the onset of GD and shrank during remission of GD under medical treatment, despite persistently positive TRAb levels.
We support the hypothesis that two different pathogenic mechanisms might be responsible for thymus enlargement: thymic cortical tissue expansion seems to be due to a hyperthyroid state, while lymphoid hyperplasia appears to correlate with immune abnormalities underlying GD.
格雷夫斯病（GD）通常与其他自身免疫性疾病相关，GD 与胸腺增生（TH）之间也存在罕见但有充分记录的关联。由于大多数病例无症状且未得到彻底检查，因此很难确定这种关联的真实频率。
我们回顾了与 GD 相关的胸腺肿大的文献，发现迄今为止已发表了 107 例病例。仅在 4 例患者中记录到胸腺癌，而大多数病例被诊断为 TH。GD 相关 TH 的发病机制尚未完全阐明。一些研究支持 TSH 受体抗体（TRAb）介导胸腺肿大的假说。
我们报告了一名女性 GD 患者，其偶然发现前纵隔肿块。我们的病例与 TRAb 介导机制的假说不一致，因为尽管 TRAb 水平持续阳性，但在 GD 缓解期间，GD 发病时胸腺达到最大体积并在药物治疗期间缩小。
我们支持这样一种假说，即两种不同的发病机制可能导致胸腺肿大：胸腺皮质组织扩张似乎是由于甲状腺功能亢进状态引起的，而淋巴样增生似乎与 GD 潜在的免疫异常相关。
