When Evaluating a New Thyroid Mass and a Ring-Enhancing Brain Lesion (When Two Presentations Collide)

We aimed to evaluate the clinical and pathologic features of two common medical illnesses and their appropriate workup and pathognomonic findings. A 57-year-old white male presented with a new onset expressive aphasia while traveling abroad. He was evaluated at an outside facility and underwent workup for a stroke. The evaluation included a CT and MRI of the brain demonstrating three new enhancing lesions, the largest of which was a 2.5 cm ring-enhancing cystic lesion. A CT of the chest noted a 4-cm cystic thyroid lesion that was diagnosed as a thyroid cancer with brain metastases. The patient was told that he had cancer and needed therapy. The patient elected to be treated closer to home and presented to our institution with a referral for brain irradiation. The patient was evaluated and his case was reviewed in a neuro/oncology tumor board, where several other possible diagnoses were considered. A complete workup was performed, including two separate FNAs of the thyroid mass along with a PET scan, CEA test, CBC test, CMP, CRP, sed rate, and SLE testing, along with a spinal tap (cytology, protein, and serology). The MRI on further review showed that one of the lesions was a periventricular enhancing area and the largest lesion was an open ring with T2 and DWI enhancement. The fine needle aspiration (FNA) samples of the thyroid both showed benign histology. The laboratory evaluation was negative except for a mildly elevated CRP with no tumor markers identified and the spinal tap was positive for elevated protein and particularly oligoclonal bands. The PET scan showed no sites of fluorodeoxyglucose (FDG) avid masses including the thyroid. Multiple sclerosis (MS) represents 400,000 cases in the US and benign thyroid nodules noted on imaging range from 19-35% of the population. One pathognomonic finding of MS that is less common is the open rings called tumefactive lesions versus the closed rings seen with metastases. A cystic thyroid lesion can range from a benign process to a differentiated thyroid cancer. The rate of distant metastasis with these cancers ranges from 1-23% in the literature. Lung and bone metastasis are the most common sites with CNS metastasis only accounting for < 2% of the cases. A better understanding of these findings should allow physicians to have a higher degree of suspicion in these cases and provoke further inquiry to prevent unnecessary injury.