Glioblastoma Multiforme and Papillary Thyroid Carcinoma: Rare Combination of Primary Malignancies

Introduction: Studies have reported thyroid cancer patients are potentially at 30% increased risk of getting second primary cancer when compared to the general population. We are describing a young Caucasian male patient who was diagnosed with two synchronous cancers, papillary thyroid cancer (PTC) and glioblastoma multiforme (GBM). Case Report: A 52 year old Caucasian male with past medical history of hypertension, partial right thyroidectomy in 1999 for thyroid nodular disease, and postsurgical hypothyroidism on levothyroxine. He underwent FNA of left thyroid nodule found on routine monitoring of thyroid nodules showed to be suspicious for malignancy. He underwent left hemi-thyroidectomy in July 2019, revealing PTC, follicular variant, encapsulated, noninvasive type measuring 0.9 x 0.9 x 0.5 cm, completely excised with negative margins; reminder of the right hemi-thyroidectomy performed in February 2020, revealing cystic adenomatoid nodule and no evidence of malignancy. Postoperative thyroglobulin and thyroglobulin antibodies levels were undetectable. A diagnostic whole body iodine scan didn’t show metastasis hence Iodine-131 treatment was not warranted. A week following the right hemi-thyroidectomy he presents to the ER with apraxia, difficulty with concentration, visual difficulty, headaches. CT scan of the brain revealed left occipital region revealed a 3.7 x 2.3 cm lesion concerning for malignancy. A follow up contrast-enhanced MRI brain showing multiple ring-enhancing lesions identified within the left posterior occipital lobe measuring 1.7 x 1.8 cm, additional occipital lobe lesion measuring 2.7 cm, mid and posterior parietal lobe measuring 3.0 cm extending to collateral sulcus measuring 2 x 3 x 1.9 cm compressing the posterior horn of left lateral ventricle. Patient underwent suboccipital craniotomy, pathology revealing glioblastoma NOS, WHO grade IV; further biomarker analysis was not available. CT of the chest, abdomen, pelvis showed no evidence of metastatic disease. Postoperative MRI of the brain revealed postoperative changes with resection of the left occipital portion of the lesion with additional enhancing regions in the left parietal and temporal lobes and splenium unchanged. Patient underwent concurrent, definitive chemo-radiation with temozolomide, now on maintenance temozolomide and levothyroxine. Conclusion: PTC is the most common thyroid malignancy, affecting young patients less than 45 years old. GBM can occur in people of any age, but they are more frequent in older adults. Physicians should maintain high surveillance for second primary cancers at a variety of sites in patients who have been found or treated for primary cancers, especially at a young age. Further evaluation of genetic and environmental factors between papillary thyroid cancer and glioblastoma multiforme will improve our understanding of the etiology of these malignancies.