Thyroid disease is common in pregnancy but malignant thyroid nodules are rare. We present a pregnant woman diagnosed with differentiated papillary thyroid cancer (PTC) which progressed to metastatic disease.
A 28 year old presented at 15 weeks gestation for management of subclinical hypothyroidism with a TSH of 4.8 and free T4 of 8.2. An incidental non-tender nodule was noted. Thyroid ultrasound conveyed a 6mm x 8mm x 10mm TI-RADS 5 right lower pole solid nodule with internal microcalcification. Subsequent FNA indicated PTC Bethesda 6 classification. MDT discussion with patient and family concluded delaying surgery until postpartum was appropriate. She underwent serial sonography second monthly. Postnatally, a CT neck showed no lymphadenopathy though noted concerning pulmonary nodules. Consequently, she underwent a total thyroidectomy two months postpartum. Histopathology confirmed a 12mm right PTC with two separate 8mm foci of micropapillary thyroid carcinoma and two of six metastatic lymph nodes. She was referred for radioactive iodine.
Thyroid cancer in pregnancy is challenging. The mainstay in evaluation is ultrasonography with TI-RADS classification. FNA of suspicious nodules is safe in pregnancy with use of Bethesda classification to determine further management. Pregnancy termination is not required for PTC. Definitive treatment involves subtotal or complete thyroidectomy but surgery timing during pregnancy has various complexities. Without surgery, there is potentially an increased risk of progression due to hormonal effect, though this remains unsubstantiated. Surgery carries a higher chance of complications including mortality and longer hospital stay. Consensus is to avoid surgery in first and third trimesters due to increased risk of foetal and maternal complications.
Given the delay in surgical management, early CT radiography was and should be considered post-delivery to detect metastatic disease. Although uncommon, the risk of progression should be discussed with women and their families to ensure an informed decision is made regarding treatment options.