2019 Volume 68 Issue 1 Pages 173-179
A 74-year-old male presented to our hospital with high-level carcinoembryonic antigen (CEA) revealed during a routine medical checkup. Positron emission tomography–computed tomography revealed fluorodeoxyglucose-avid lesions in the hypopharynx and the right lobe of the thyroid gland, leading to his referral to the Department of Otorhinolaryngology. A lesion in the right piriform fossa was diagnosed as hypopharyngeal carcinoma, but a tumor in the thyroid gland could not be confirmed. Several days after the initiation of chemotherapy for hypopharyngeal carcinoma, the patient developed fever, and blood tests revealed elevations in C-reactive protein (CRP; 19.17 mg/dL) and procalcitonin (PCT; 47.90 ng/mL) levels. The blood culture sample showed negative results after 5 days of incubation. As the serum PCT level remained high at 37.57 ng/mL despite the abatement of fever and CRP level reduction, a tumor in the thyroid gland was suspected as medullary thyroid carcinoma (MTC). Further investigation revealed elevations in the serum CEA and calcitonin levels. In addition, scintigraphy scan revealed a lesion in the right thyroid lobe more slightly 123I metaiodobenzylguanidine-avid than that in the left. Eventually, the patient underwent total thyroidectomy and lymphadenectomy, and his serum PCT level decreased to below the cutoff value within 2 days after surgery. The thyroid tumor of this patient was diagnosed as MTC on the basis of histopathological examination results. Thus, this case suggests that the high serum PCT level could be attributed to MTC.
