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Collision tumor of a papillary and follicular thyroid carcinoma: A second case report in Saudi Arabia and literature review

Year: 2026

Type: article

Abstract: A collision tumor is a rare occurrence in which two distinct tumor types coexist within an organ while maintaining distinct borders. A 61-year-old female referred to our clinic for the evaluation of a thyroid mass. Ultrasound revealed a large, solid, isoechoic nodule in the right lobe measuring 4.5 × 3.1 cm (TI-RADS category 3). Fine-needle aspiration biopsy was suspicious for a follicular neoplasm, Hürthle cell (oncocytic) type, Bethesda system class IV. The patient underwent right lobectomy, and the final pathology report revealed minimally invasive follicular carcinoma. Completion thyroidectomy revealed papillary carcinoma of the left lobe. Managing thyroid collision tumors is challenging due to the presence of two distinct tumors with different biological aggressiveness, treatment options, and prognoses. Addressing how these factors influence treatment planning can enhance understanding of patient management and outcomes. • Collision tumors of the thyroid are rare entities where two histologically distinct carcinomas coexist within the same gland, maintaining separate boundaries. • This case represents only the second reported instance in Saudi Arabia of a collision tumor comprising both papillary and follicular thyroid carcinomas. • Diagnosis and management are challenging due to differing biological behavior, requiring a tailored, often multidisciplinary treatment approach. • Fine-needle aspiration may suggest one tumor type, but final histopathology remains essential to identify coexisting malignancies. • Awareness of such rare occurrences can improve clinical suspicion, guide surgical planning, and prompt comprehensive histopathological evaluation.

Source: Journal of Clinical and Translational Endocrinology Case Reports

DOI: 10.1016/j.jecr.2026.100210

Authors: Saja Aqeel Al-Aqeel, Aqilah Ali Al-Abbad, Mohammed Fahad Al-Mazyad, Michael Lorentziadis

Institutions: Imam Abdulrahman Al Faisal Hospital, King Fahd Military Medical Complex

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: gold

Estimated APC paid: $1,260