Endocrine Abstracts

JOINT1110

Introduction: Subacute thyroiditis during pregnancy is a rare condition, with an incidence of 10-20 cases per 1,000,000 pregnancies [1]. It can mimic thyroid cancer, which has an incidence of 3.6-14 cases per 100,000 pregnant women [2].

Case Presentation: A 31-year-old woman, at 6 weeks of pregnancy, presented with right-sided neck pain and difficulty swallowing. Laboratory tests revealed elevated inflammatory markers: C-reactive protein 190 mg/l, erythrocyte sedimentation rate 27 mm/h, and white blood cell count (WBC) 10.9 x 10^9/l, ANtiTPO, AntiTg – negative, euthyrosis. Ultrasound of the thyroid showed a significantly enlarged right lobe, containing a large, hypoechoic, heterogeneous, and hypervascular nodule measuring approximately 4.4 x 3.3 x 3.5 cm. The nodule exhibited multiple calcifications of varying sizes, along with avascular areas, while the left lobe appeared normal. A suspicious 0.5 cm lymph node was identified in the right side of the neck (zone IV). Based on these findings, a percutaneous fine needle aspiration biopsy was performed under ultrasound guidance, with three tissue columns collected for histopathological examination. The patient was started on ibuprofen for pain and inflammation, and over the course of her treatment, there was improvement in the inflammatory markers, and her symptoms vanished. Biopsy results revealed differentiated high-grade thyroid carcinoma (DHGTC) with areas of tumor necrosis. Immunohistochemistry showed that tumor cells were positive for TTF-1, PAX-8, CK-19, and weakly positive for thyroglobulin, but negative for BRAF. The Ki-67 proliferation index was 7%. Surgical treatment was recommended. Due to the pregnancy, surgery was planned for the second trimester. A total thyroidectomy was performed, and a lymph node in zone VI, measuring 4 mm posterior to the right thyroid lobe, was also removed. The histological examination of the excised tissue confirmed the diagnosis of DHGTC carcinoma, staged as pT3 N0a LVI1. Following surgery, the patient was started on thyroxine replacement therapy with TSH suppression. In conclusion, this case highlights the diagnostic challenge of distinguishing subacute thyroiditis from thyroid cancer during pregnancy. Despite the initial suspicion of subacute thyroiditis, further investigation revealed high-grade differentiated thyroid carcinoma. DHGTC has an intermediate prognosis, falling between well-differentiated thyroid carcinoma and anaplastic thyroid carcinoma [3]. Well-differentiated tumors do not require immediate surgical treatment but only observation during pregnancy. On the contrary, more aggressive tumors (as in our case), also undifferentiated, require surgery during pregnancy, as delay in such circumstances can significantly reduce survival [4].

1. Doi:10.1089/thy.2016.0457 2. PMCID: PMC3272870 3. Doi: 10.3390/curroncol31060252. 4. Doi:10.21037/gs-24-52