Incidental Diagnosis of Thyroid Medullary Microcarcinoma in a Patient with Long Standing Graves' Disease Presenting with Thyroid Storm

Sporadic medullary thyroid cancer (MTC) accounts for approximately 75 percent of all cases of the disease. The clinical presentation and manifestations of MEN2-associated MTC are similar to those of sporadic MTC. The most common presentation is that of a solitary thyroid nodule or cervical lymphadenopathy. We present a case of 70-year-old woman with a long-standing history of Graves' disease who presented with Thyroid storm and found to have Thyroid Medullary Microcarcinoma on surgical pathology.

Case Description:

70-year-old female with PMH of Graves' disease, Paroxysmal Atrial Fibrillation, CHF and HTN who presented to ED with Shortness of breath and weakness. She reported shortness of breath has been worsening especially for last three weeks. She was diagnosed with Graves' disease 15 years prior to presentation, treated with Methimazole which was stopped 2 years prior due to stable disease and remission. EKG revealed Atrial fibrillation with rapid ventricular response, heart rate was 144 with irregularly irregular rhythm and she was treated with intravenous Diltiazem. On presentation, her tests revealed TSH < 0.01, Free T4 1.57 and Free T3 1.7 and her Thyroid Ultrasound showed slightly heterogeneous thyroid echotexture without discrete solid or cystic lesions. She was started on Methimazole 15 mg BID, subsequently changed to Propylthiouracil 200 mg every 4 hours and Propranolol 40 mg Q6h given Burch Wartofsky Scale 25 suggestive of impending Thyroid Storm. Cholestyramine 4 grams 4 times a day and intravenous Hydrocortisone 100 mg every 8 hours added subsequently. Her hospital course was eventful for worsening respiratory status and hemodynamic instability requiring ICU care, endotracheal intubation with mechanical ventilation and vasopressor support with intravenous norepinephrine drip. After clinical stability and aggressive medical management of thyrotoxicosis, she was successfully extubated and discharged from hospital in a stable condition. She was followed up outpatient and scheduled Total Thyroidectomy performed with preoperative treatment with Lugol's solution and Cholestyramine. Surgical pathology showed Thyroid gland with diffuse follicular and papillary hyperplasia, consistent with Graves' disease, Medullary Microcarcinoma, 0.2 cm, close to the left superior pole, not involving margin. The tumor cells showed strong positive staining for calcitonin, CEA, and chromogranin. She underwent analyses of selected hereditary cancer genes and found to have no pathogenic mutations, variants of unknown significance or gross deletions for RET gene.

Discussion:

Our case involves a woman with 15 years long standing history of Graves' disease who presented with Thyroid storm and found to have Thyroid Medullary Microcarcinoma on surgical pathology. Negative pathogenic mutations for RET making it sporadic MTC. Occurrence of Sporadic Micro medullary Thyroid Carcinoma in a patient with Graves's disease making it uncommon pathologic combination and heightens curiosity for surgical pathology diagnosis after Total Thyroidectomy.