Category: Thyroid

Monitor: 8

8 - An unusual case of non-secretory Medullary Thyroid Carcinoma in pregnancy

Friday, Apr 26
11:30 AM – 12:00 PM

Objective :

Medullary Thyroid Carcinoma (MTC) comprises of 1-2% of all thyroid cancers in the United States. Derived from the parafollicular C-cells of the thyroid, they secrete Calcitonin (Ctn) and Carcinoembryonic Antigen (CEA) which serve as tumor markers for the diagnosis, post-surgical follow-up and prognostication. Tumor size in MTC usually correlates with Ctn and CEA levels. We present an unusual case of a large non-secretory MTC presenting in pregnancy.


Methods :

A 31-year old female in her 2nd trimester of pregnancy presented with a 3-month history of right-sided neck mass associated with mild dyspnea. She did not have a past history of neck radiation or family history of malignancy. Physical examination showed a 7cm firm right-sided neck mass that moved with deglutition, without palpable lymph nodes.


Results :

Thyroid function tests were normal. Ultrasound (USG) of the neck revealed a 7.8cm mixed solid-cystic thyroid mass with punctate calcifications. There was no cervical lymphadenopathy. USG-guided fine needle aspiration of the mass was suspicious for malignancy, with features concerning for MTC. CEA was <1 (<5 ng/mL) and Ctn was 14 (0-5 pg/mL), which was in the reference range for pregnancy. The patient underwent a total thyroidectomy in her 2nd trimester and pathology showed an 8.2cm unifocal MTC, weakly positive for Ctn and negative for CEA on immunohistochemistry. She was started on levothyroxine replacement and subsequently had an uneventful pregnancy and delivery. On follow-up, her Ctn and CEA levels are undetectable, and thoraco-abdominal CT is negative for metastases.


Discussion : Non-secretory MTCs are very rare (<1% of MTCs). The pathophysiology is not understood, though de-differentiation, defective secretion, ineffective post-translational processing or production of precursor peptides have been postulated. They pose a unique dilemma regarding surveillance post-operatively. As only a few cases have been reported in the literature, there are no guidelines for surveillance. Currently, expert opinion suggests monitoring with neck USG, thoraco-abdominal CT, Ctn and CEA levels (an increase in these levels has been seen in some cases of relapse). Pro-calcitonin can be a potential biomarker. Prognosis is varied, not necessarily poor. In our patient’s case, despite a large tumor size and low Ctn levels, there is no evidence of nodal or distant metastases so far.


Conclusion :

Although non-secretory MTCs have been reported previously, this is the first report of presentation during pregnancy. Despite the large size, there was no loco-regional or distant spread. Due to the atypical features of this MTC and the uncertainty of future behavior, close follow-up is necessary.

Bahar K. Force

Endocrinology Fellow
Baylor College of Medicine
Houston, Texas

Clincal Endocrinology Fellow

Dina Winograd

Clinical Fellow
Baylor College of Medicine
Houston, Texas

Clinical Endocrinology fellow at Baylor College of Medicine

Nalini Ram

Associate Professor of Medicine
Baylor College of Medicine, Texas

Clinician and Educator

Bahar K. Force

Endocrinology Fellow
Baylor College of Medicine
Houston, Texas

Clincal Endocrinology Fellow