Work

High-Grade Papillary Thyroid Carcinoma, Diffuse Sclerosing Subtype

Year: 2025

Type: article

Abstract: High-grade differentiated thyroid carcinoma is a novel classification defined by elevated mitotic count (MC) of ≥5/2 mm 2 and/or tumor necrosis. It may assume a phenotype of papillary thyroid carcinoma, diffuse sclerosing subtype (PTC-DS), and can be termed HGPTC-DS. A detailed clinicopathologic review was conducted on a large series of 18 cases of HGPTC-DS. A control group of 41 PTC-DSs with genomic data was also included. Histologically, HGPTC-DS showed typical features of PTC-DS and HG areas, often exhibiting solid architecture of uniform squamoid cells admixed with tumor necrosis, frequently the comedo type. All HGDTC-DSs had tumor necrosis. The MC was often low (median 1/2 mm 2 ). PTC nuclear features were retained and no nuclear pleomorphism was seen. HGPTC-DS was often subjected to misdiagnosis. Among the 7 external cases, the initial diagnosis was anaplastic carcinoma in 1 and PTC in 5. Compared with PTC-DS, HGPTC-DS was associated with positive resection margin, AJCC eighth edition pT3b and pT4a/4b disease, gross extrathyroidal extension (ETE), a higher number of regional lymph nodes metastasis, a larger size of nodal metastasis, decreased recurrence-free survival (RFS) and regional recurrence-free survival ( P <0.05). Among the 9 HGPTC-DSs sequenced, 5 harbored RET fusions, 2 had STRN::ALK fusion, and 1 had BRAF p.V600E mutation. In conclusion, HGPTC-DS is a rare high-grade carcinoma characterized by uniform squamoid area with comedo-type tumor necrosis, high pT stage, gross ETE, large volume nodal metastasis, poor RFS, and RRFS. Given its rarity, it may be subjected to misdiagnosis as PTC and anaplastic carcinoma.

Source: The American Journal of Surgical Pathology

DOI: 10.1097/pas.0000000000002371

Authors: Ronald A. Ghossein, Daniel W. Scholfield, Howard Qin, Ashok R. Shaha, Ian Ganly, Bin Xu

Institution: Memorial Sloan Kettering Cancer Center

Language: English

Topic: Thyroid Cancer Diagnosis and Treatment

Subfield: Endocrinology, Diabetes and Metabolism

Field: Medicine

Domain: Health Sciences

SDG: Good health and well-being

Open Access status: green

Funder: National Cancer Institute