The columnar cell variant (CCV) of papillary thyroid carcinoma (PTC) is a rare histological subtype with distinct morphological and immunohistochemical (IHC) features, which can present diagnostic challenges. We report a case of a 13-year-old girl diagnosed with CCV of PTC (CCV-PTC) following a total thyroidectomy for a solitary thyroid nodule. Histopathological (HP) examination revealed aggressive features, including vascular invasion and extrathyroidal extension. However, no metastases or recurrences were observed during six years of follow-up. This case report provides a comprehensive analysis of a rare CCV-PTC in an adolescent, focusing on its HP, IHC, and molecular characteristics. It also discusses diagnostic pitfalls and differential diagnoses that should be considered.

Spindle epithelial tumor with thymic-like elements (SETTLE) is an extremely rare tumor that occurs primarily in the thyroid gland. Histologically, SETTLE is characterized by the presence of spindle-shaped epithelial cells and glandular structures. However, it is known that diagnosis via fine-needle aspiration cytology can be challenging. SETTLE predominantly occurs in younger individuals and has a less favorable prognosis compared to differentiated thyroid carcinoma. Therefore, ensuring accurate diagnosis and appropriate treatment is crucial. We encountered a case of spindle epithelial tumor with thymus-like differentiation in a 10-year-old patient for whom the preoperative diagnosis was successfully established through fine-needle aspiration cytology, which facilitated appropriate surgical resection. Comprehensive histopathological examination and immunohistochemical analysis are essential to ensure appropriate management and surveillance of SETTLE. A rare thyroid tumor, spindle epithelial tumor with thymic-like elements (SETTLE), was diagnosed preoperatively and treated surgically. SETTLE presents with characteristic histological features that must be recognized for accurate diagnosis. In addition, diagnosis through cytology is often challenging. The primary treatment for SETTLE is surgical intervention as radiotherapy and pharmacological treatments are generally not expected to be highly effective. Radical resection is the only effective treatment, making the selection of the surgical procedure according to the stage of the disease essential.

Sclerosing mucoepidermoid carcinoma of the thyroid with eosinophilia (SMECE) is a rare thyroid tumor. More and more reports have proposed that sclerosing mucoepidermoid carcinoma of the thyroid with eosinophilia is significantly invasive, but its origin and pathogenesis are currently controversial. We presented a 42-year-old female of Han ethnicity. She had a 4-year history of thyroid nodules, and mild decrease in thyroid function was observed at the time of surgery. Subsequently, pathological examination revealed typical morphological characteristics of sclerosing mucoepidermoid carcinoma of the thyroid with eosinophilia. Compared with surrounding normal thyroid tissues, significant eosinophil infiltration was observed in the tumor stroma. Negative thyroglobulin immunohistochemical staining and uniquely positive expression of tumor protein p63 and cytokeratin 5/6 were detected in tumor cells. No genetic mutation was detected by next-generation sequencing. No extrathyroid invasion, lymph node metastasis, or distant metastasis was found. The patient was alive without evidence of disease after 24 months of follow-up. The case presentation supported this point that sclerosing mucoepidermoid carcinoma of the thyroid with eosinophilia originated from solid cell nests, and eosinophils might play an important role in the tumorigenesis and development of sclerosing mucoepidermoid carcinoma of the thyroid with eosinophilia. In addition, a comprehensive analysis of the previously reported cases from reported literature revealed that age and distant metastasis might be the risk factors affecting prognosis.

Objective: Intrathyroid thymic carcinoma（ITTC） is a rare thyroid tumor that lacks typical clinical manifestations and imaging features, making preoperative diagnosis challenging.The primary treatment for ITTC is radical surgery; however, the effectiveness of adjuvant radiotherapy and chemotherapy post-surgery is not well-established. This paper presents a case of ITTC , analyzing the clinical data and correlating it with the literature to explore the clinical manifestations, diagnostic approach, treatment, and prognosis of ITTC. 目的：甲状腺内胸腺癌（intrathyroid thymic carcinoma，ITTC）是一种罕见的甲状腺肿瘤，缺乏典型的临床表现及影像学特征，术前诊断较为困难，根治性手术治疗是其首选的治疗方式，术后是否辅以放化疗，尚无明确结论。本文报道1例ITTC患者，分析该病例临床资料并结合相关文献，探讨ITTC的临床表现、诊疗及预后。.

Papillary thyroid carcinoma (PTC) accounts for about 60% of adult thyroid carcinoma and generally has an excellent prognosis. Primary squamous cell carcinoma of thyroid (PSCCT) is a rare thyroid tumor with high malignancy and poor prognosis. In 2022, the 5th edition of World Health Organization (WHO) has classified it as a subtype of anaplastic thyroid carcinoma (ATC), abbreviated as ATC-squamous cell carcinoma (SCC) subtype. Poorly differentiated thyroid carcinoma (PDTC) is a kind of follicular-derived malignancy, which is prone to recurrence and distant metastasis. Here, we report a rare case of the coexistence of PTC, ATC-SCC subtype and PDTC. We herein report a case of 69-year-old female who initially presented with a history of left neck mass for one month. Comprehensive auxiliary examinations and postoperative pathology confirmed the diagnosis of PTC combined with ATC-SCC subtype, and PDTC. Total thyroidectomy with radical left cervical lymph node dissection was performed, followed by thyroid-stimulating hormone (TSH) suppressive therapy, 131I, radiotherapy and chemotherapy. The patient showed no tumor recurrence or metastasis after a 5-month postoperative follow-up. The simultaneous occurrence of PTC, ATC-SCC subtype, and PDTC is extremely rare in clinical terms or literature reports. The treatment has not been standardized, and early radical surgery is the first choice. In addition, the combination of adjuvant therapies such as TSH suppressive therapy, radiotherapy, chemotherapy and 131I may further improve the prognosis of the patient.