An Anaplastic Thyroid Carcinoma of the Giant-Cell Type from a Mediastinal Ectopic Thyroid Gland

Abstract

Anaplastic thyroid carcinoma is a rare, aggressive form of thyroid carcinoma with a mean survival of less than 6 months. Ectopic thyroid tissue can be present in the mediastinum due to faulty embryogenesis with improper descent. Primary thyroid malignancies may arise from this ectopic tissue. A 90-year-old male with a history of prostatic adenocarcinoma, hypothyroidism, and occupational and therapeutic exposure to radiation presented with a rash on his chest. A review of the dermatopathology and excised mediastinal specimen revealed rare papillary foci that tested positive for thyroid markers from a background of poorly differentiated components. Molecular analysis confirmed a BRAF V600E mutation in the specimen. The final diagnosis was anaplastic thyroid carcinoma of the giant-cell type. Given the atrophic cervical thyroid tissue in the patient’s neck with no evidence of previous surgery, this carcinoma was believed to arise from ectopic mediastinal tissue associated with cutaneous and bony metastasis. In conclusion, anaplastic thyroid carcinoma is an aggressive and rare thyroid malignancy that can arise from ectopic thyroid tissue in the mediastinum and should be considered in the differential diagnosis of primary undifferentiated mediastinal malignancies with bony involvement.

Personalized Management of Malignant and Non-Malignant Ectopic Mediastinal Thyroid: A Proposed 10-Item Algorithm Approach

“…All types of thyroid cancer have been reported in ectopic thyroid tissue as well as different areas of thyroiditis involvement [7,[34][35][36]. Notably, some authors consider that the rate of malignant transformation in ectopic sites is similar with eutopic thyroid (particularly, for the papillary thyroid cancer [37]), but the level of statistical Cancers 2024, 16, 1868 4 of 58 evidence in this particular matter remains low [8,38]. For instance, the 2023 study of Gao et al [7] (which is described by the authors as being "the world's largest single-center sample size of comprehensive ectopic thyroid gland diagnosis and treatment" that included patients treated between 2013 and 2022) investigated 47 patients (five subjects had a double ectopic tissue, thus a total number of 52 ectopic thyroids) with different ectopic presentations showed that 61.7% of them had an accessory thyroid tissue; 78.7% were females; average age at diagnosis was of 36 years (range between 4 months and 65 years); the average maximum diameter of the ectopic tissue was of 3.2 cm; the most common sites were lingual (N = 20/52 thyroid tissues), followed by submandibular (N = 10/52), latero-cervical (N = 10/52), mediastinal (N = 4/52), ovarian (N = 7/52), and esophageal (N = 1/52).…”

“…In additional to these clinical elements that are directly connected to the presence of the mediastinal lesion, highly aggressive malignancy in EMTs might be detected due to local or distant malignant spreading as the first step of further undergoing EMT identification. Here, we introduce the cases with thyroid cancer in EMTs (regardless of the scenario of detection) according to our methods [36,37,41,42,55,[58][59][60][61][62][63][64][65][66][67][68][69][70][71][72] (Table 2).…”

“…Table 2. Case reports of EMT underlying different types of malignancy according to our methods; the display starts with the most recent publication date [36,37,41,42,55,[58][59][60][61][62][63][64][65][66][67][68][69][70][71][72]. Regardless of the pathological traits, awareness of EMTs is essential, while removal was decided in most of the cases (rather than conservative approach) depending on the location and EMT anatomical features; the risk of malignancy (the rate of conversion from benign to a malignant EMT is not clearly understood, especially in long standing goiter-like EMT); the ectopic tissue enlargement with compressive symptoms/signs such as respiratory obstruction or compression on mediastinal organs; the risk of hemorrhage [84]; the patient's co-morbidities and medical/surgical history as well as the general health status [7,13].…”

“…There are current ga approach: a low index of s neither for opting in favo post-operatory 100 mCI → whole body scan: no metastasis → no " gross " recurrence after 14 months since admission Nguyen [37] 2023 M 90…”

“…One short note: 19 papers introduced a single case report per article [36,37,41,42,[58][59][60][61][62][63][64][65][66][67][68][69][70][71][72] and another publication presented two patients [55], leading to a total of 21 patients with any type of malignancy in EMTs. Specifically, primary thyroid cancer was identified in 20 patients (plus, a case of a one newborn displayed an immature teratoma hosted by the EMT [68]).…”