Malignant teratoma of the thyroid: A difficult diagnosis by fine‐needle aspiration

Abstract

Primary thyroid teratomas are rare, usually benign, and typically occur in children. We report the unusual occurrence of a malignant thyroid teratoma in a young man. Initial ultrasound and CT studies revealed an 8.5 heterogeneous mass involving the entire right thyroid lobe causing tracheal compression and deviation. Fine‐needle aspiration (FNA) revealed malignant cells with possible neuroendocrine features. Similar findings have been previously reported, with an occasional interpretation as possible medullary thyroid carcinoma. In no report, as with our case, has the correct diagnosis been suggested with FNA. The surgical specimen contained abundant primitive neuroepithelium with a very minor component of mature ectodermal tissue in one area. Like this case, an abundance of immature neuroepithelium has been reported in essentially all previous reports of primary malignant thyroid teratoma, sometimes creating a challenge to find another type of germ cell tissue. Array comparative genomic hybridization studies in this case revealed a markedly complex karyotype including gain of chromosome 12 and loss of 17p. Amplification of MYCN, EWSR1 rearrangement and isochromosome 12p were not identified, providing no evidence for neuroblastoma or Ewing sarcoma/peripheral neuroectodermal tumor, both of which have also rarely been reported as primary thyroid tumors. With the use of cisplatinum‐based chemotherapy combined with radiation, survival times have increased dramatically. Our patient is now disease free and back to his normal activities after relatively short follow‐up. Although rare, it is important to be aware that teratomas may present as a thyroid nodule. Recognition by FNA is challenging, and requires multiple modalities for full identification.

Malignant teratoid tumor of the thyroid gland: an aggressive primitive multiphenotypic malignancy showing organotypical elements and frequent DICER1 alterations—is the term “thyroblastoma” more appropriate?

“…In line with a distinct clinicopathological and molecular entity, malignant teratomas lack isochromosome 12, a genetic hallmark in the majority of germ cell neoplasms [9,[13][14][15][16]. Rabinowits et al reported in 2017 for the first time the presence of a pathogenic DICER1 mutation (c.5438A > G; p.Gln1813Glu) in a case of malignant thyroid teratoma in a 59-year-old female [9].…”

Primary thyroid teratoma in adults: A case report and systematic review of the literature

“…More specifically, the location of recurrence in these 11 patients was the thyroid bed (n=4), the central compartment lymph nodes (n=3), the lateral lymph nodes (n=2) and the mediastinum (n=2). The proportion of patients who needed reoperation after their first surgery due to recurrence, either in the thyroid bed or in regional lymph nodes was 22.7% (n=5 out of 22 cases) (1,2,4,14,16). Distant metastases occurred in 8 (29.6%) patients; 5 (62.5%) had bone metastases, 3 (37.5%) had lung metastases and 3 (37.5%) were diagnosed with metastases in paraaortic and clavicular lymph nodes (4,11,(18)(19)(20).…”

“…A total of 15 studies (11 case reports and 4 case series) described outcomes for 27 patients who were diagnosed with PTT and underwent thyroidectomy and in some cases an additional neck dissection (1,2,4,8,9,(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). One study was excluded from the present systematic review (6).…”

“…Extragonadal germ cells tumors are uncommon in adults and only 2-5% of teratomas can develop in extragonadal sites (1,2). The most frequent extragonadal teratoma locations are anterior mediastinum and retroperitoneum in almost, occurring 60 and 40% of cases, respectively (1). However, the proportion of head and neck teratomas is approximately 6% (3)(4)(5).…”

The decisive role of molecular pathology in presumed somatic metastases of type II testicular germ cell tumors: report of 2 cases

“…Interestingly, 12p gain has been described in other malignancies, including malignant teratoma of the thyroid (considered as an extragonadal germ cell tumor) [9] but also in pancreatic carcinomas [10]. However, the amplified region in pancreatic carcinomas is located proximal to the amplified region in TGCT [10].…”