A case report of thyroid sarcomatoid carcinoma

Rationale: Sarcomatoid carcinoma represents a rare subtype of highly aggressive malignant neoplasm. Sarcomatoid carcinoma of the thyroid is extremely uncommon, accounting for merely 1% to 2% of all thyroid malignancies. It is marked by rapid progression and unfavorable prognosis, with a median survival of only 5 to 6 months. Additional case data are required to assist clinicians in the diagnosis and treatment of this rare disorder. Patient concerns: A 65-year-old male presented with fever and left cervical pain. Physical examination identified a hard palpable mass within the left thyroid lobe. Diagnoses: Thyroid ultrasonography revealed a hypoechoic nodule within the left lobe, with an anterior-posterior-to-transverse diameter ratio >1; circumferential calcification and scattered intranodular blood flow signals were observed. Additionally, enlarged and fused left cervical lymph nodes were identified. Computed tomography demonstrated that a left thyroid mass was compressing the trachea. A percutaneous fine-needle aspiration biopsy combined with immunohistochemical staining (showing positivity for both cytokeratin and vimentin) ultimately confirmed the diagnosis of thyroid sarcomatoid carcinoma. Interventions: Following multidisciplinary team consultation, the patient underwent 4 cycles of combination therapy with sintilimab, paclitaxel, and anlotinib. Outcomes: The patient achieved disease remission after combination therapy but ultimately died of disease progression 9 months post-diagnosis. Lessons: This sarcomatoid carcinoma of the thyroid case presents typical clinical and ultrasonographic manifestations. Pathological assessment combined with immunohistochemistry facilitates definitive diagnosis. The adopted combination regimen yielded temporary disease control. This case provides valuable references for the individualized diagnosis and management of this rare thyroid malignancy.