Coexistence of Two Different Thyroid Malignancies: A Collision Phenomenon

Area of Science:

• Endocrinology
• Oncology
• Pathology

Background:

• Collision tumors are defined as two or more distinct neoplastic morphologies coexisting in the same organ, separated by normal tissue.
• Simultaneous occurrence of papillary thyroid carcinoma (PTC) and follicular thyroid carcinoma (FTC) within the same thyroid lobe represents an exceptionally rare pathological entity.
• The management of thyroid collision tumors is often intricate due to the presence of diverse pathologies and limited existing literature.

Observation:

• A 79-year-old male presented with hip pain secondary to a lytic bone lesion, initially suspected to be metastatic follicular thyroid carcinoma (FTC).
• Subsequent imaging revealed an enlarged thyroid gland with a cystic lesion in the left lobe.
• Histopathological examination of the thyroid specimen confirmed the coexistence of two distinct primary malignancies: papillary thyroid carcinoma (PTC) and follicular thyroid carcinoma (FTC).

Findings:

• Histopathology confirmed the simultaneous presence of both papillary thyroid carcinoma (PTC) and follicular thyroid carcinoma (FTC) in the left thyroid lobe.
• Genetic analysis for RAS gene mutations yielded negative results.
• The patient was treated with total thyroidectomy, followed by levothyroxine suppression and radioactive iodine therapy.

Implications:

• This case highlights the rare phenomenon of simultaneous distinct thyroid neoplasms, suggesting potential simultaneous mutations in different genes.
• Individualized treatment strategies are crucial for managing complex thyroid collision tumors.
• Further research into the genetic underpinnings of coexisting thyroid carcinomas is warranted to understand their pathogenesis and optimize therapeutic approaches.