Endocrine Abstracts

Introduction: Simultaneous papillary thyroid carcinoma (PTC) and follicular thyroid carcinoma (FTC) of the same thyroid lobe is a very rare pathology.

Purpose of the presentation: The objective of this work is to determine the clinical, histological and therapeutic aspects of an association of papillary thyroid carcinoma (PTC) and follicular thyroid carcinoma (FTC) on the same thyroid lobe.

Methods: We report 2 cases of PTC and FTC on the same thyroid lobe, treated in the ENT department of Fattouma Bourguiba hospital in Monastir over a period of 21 years (2000-2020).

Case1: A 22-year-old woman was referred to our department due to nodules in the right thyroid lobe detected on ultrasonography during a routine health check-up. the thyroid function tests were normal. Ultra sound showed multiples nodules in the right lobe, the biggest one was 20mm and classified as EUTIRADS IV. The patient underwent a right lobo-isthmectomy with an extemporaneous examination that suggest the benignity. Postoperative pathology revealed that the nodule with a size of about 18 mm in the right lobe was a follicular thyroid carcinoma with angio-invasionassociated with another nodule in the same lobe that was a micro papillary carcinoma (6mm) developed on a lymphocytic thyroiditis. The patient underwent a totalisation with central ipsilateral lymph-node dissection 1month later. She was initiated with thyroid hormone replacement therapy and a radioactive iodine treatment. The evolution was judged good, no recurrence or metastasis, with a follow-up of 20 months.

Case2: A 54-year-old women was evaluated at our hospital for a quick installation of a paraplegia. X-ray-imaging revealed a spinal compression. Vertebral biopsy was suggestive of a bone metastasis of a follicular thyroid carcinoma. Cervical ultrasonography showed a 29mm nodule in the right lobe that was suspected of malignancy. The patient underwent a total thyroidectomy with bilateral central lymph node dissection. There were no postoperative complications. Final histological examination revealed the coexistence of a large invasive follicular carcinoma associated with a micro papillary carcinoma in the right lobe of the thyroid. She was initiated on suppressive doses of thyroid hormone replacement therapy, a radioactive iodine treatment and vertebral radiotherapy. During its monitoring, the patient developed skull, femoral and spinal dorsal metastases with the indication of external radiotherapy.

Conclusion: Pathologists and surgeons should be aware of the possibility of the simultaneous presence of PTC and FTC tumours to avoid possible misdiagnoses.