title: Normal preoperative calcitonin levels do not always exclude medullary thyroid carcinoma in patients with large palpable thyroid masses.
abstract: Medullary thyroid carcinoma (MCT) is a sporadic or familial tumor of the parafollicular or C-cells that secretes calcitonin. The sporadic form usually presents with a palpable thyroid nodule or cervical adenopathy, by which time basal calcitonin levels are almost always elevated. Without special stains, fine-needle biopsy may fail to detect MCT. Recently, several investigators have recommended routine measurement of serum calcitonin in patients with nodular thyroid diseases for the preoperative diagnosis of MCT. A 31-year-old woman had a large palpable MCT with normal calcitonin and carcinoembryonic antigen levels before surgery. Fine-needle aspiration (FNA) demonstrated atypical cells but was not diagnostic of MCT. Pathology revealed a 3 x 4.5 x 2.3 cm MCT. Immunochemical stains showed immunoreactivity for calcitonin and synaptophysin, but no immunoreactivity to thyroglobulin. Postoperative basal and pentagastrin-stimulated calcitonin levels have remained undetectable without evidence of recurrent cancer. We have evaluated six other patients with MCT that were palpable. They had preoperative calcitonin levels ranging from 322-50,032 pmol/L. This unique case of a woman with a 4.5-cm MCT and normal preoperative calcitonin levels, emphasizes the need for careful clinical evaluation and FNA biopsy in managing patients with nodular thyroid disease.
authors.affiliation: Department of Medicine, Louisiana State University Health Sciences Center, Shreveport, USA.
authors.forename: A H
authors.initials: AH
authors.lastname: Redding
authors.forename: S N
authors.initials: SN
authors.lastname: Levine
authors.forename: M R
authors.initials: MR
authors.lastname: Fowler
mesh_terms: D000328:Adult; D001707:Biopsy, Needle; D002116:Calcitonin / Q000032:analysis / Q000097:blood*; D018276:Carcinoma, Medullary / Q000737:chemistry / Q000378:metabolism* / Q000473:pathology*; D005260:Female; D006801:Humans; D010173:Palpation; D016708:Synaptophysin / Q000032:analysis; D013954:Thyroglobulin / Q000032:analysis; D013964:Thyroid Neoplasms / Q000737:chemistry / Q000378:metabolism* / Q000473:pathology*
chemical_list: D016708:Synaptophysin; D002116:Calcitonin; D013954:Thyroglobulin