Sato Kimiya, Thompson Lester D R, Miyai Kosuke, Kono Takako, Tsuda Hitoshi
Department of Basic Pathology, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama, 359-8513, Japan.
Department of Pathology, Woodland Hills Medical Center, 5601 De Soto Avenue, Woodland Hills, CA, 91367, USA.
Head Neck Pathol. 2018 Jun;12(2):202-209. doi: 10.1007/s12105-017-0854-6. Epub 2017 Sep 6.
Ectopic hamartomatous thymoma (EHT) is a rare benign neoplasm of the lower neck suggesting branchial origin. Despite use of the term thymoma in the nomenclature, there is no evidence of thymic origin or differentiation. It affects middle-aged adults with a remarkable male predominance. To date less than 80 cases have been reported in the English literature. We present here two additional cases of EHT. The first is a benign case in a 31-year-old man, showing typical histological features. The second is a malignant case in a 70-year-old woman, showing intraductal carcinoma arising in intimate association with an EHT. These cases are presented in the context of a review of cases reported in the English literature. The exact origin has not been identified, but is considered to be of branchial apparatus, creating a quandary about the best terminology. Recently, the designation "branchial anlage mixed tumor" or "thymic anlage tumor" were proposed, but do not quite reflect the true nature of the neoplasm. To avoid taxonomic confusion, international consensus on terminology is desired. As this entity is a neoplasm that shows dual mesoderm and endoderm derivation/differentiation, we propose a new name "biphenotypic branchioma."
异位错构瘤性胸腺瘤（EHT）是一种罕见的下颈部良性肿瘤，提示其起源于鳃器。尽管在命名中使用了胸腺瘤这一术语，但并无胸腺起源或分化的证据。它好发于中年成年人，男性明显居多。迄今为止，英文文献报道的病例不足80例。我们在此报告另外两例EHT。第一例为一名31岁男性的良性病例，具有典型的组织学特征。第二例为一名70岁女性的恶性病例，显示导管内癌与EHT密切相关。这些病例是在对英文文献报道的病例进行综述的背景下呈现的。确切起源尚未明确，但被认为是鳃器来源，这给最佳术语的确定带来了难题。最近，有人提出“鳃原基混合瘤”或“胸腺原基肿瘤”的命名，但并不完全反映该肿瘤的真实性质。为避免分类学上的混淆，需要在术语上达成国际共识。由于该实体肿瘤显示出中胚层和内胚层的双重起源/分化，我们提出一个新名称“双表型鳃瘤”。
