Endocrine Abstracts

Sporadic Medullary thyroid carcinoma (MTC) is an uncommon thyroid cancer. The prevalence has been studied in two large European studies(1,2). Serum calcitonin provides a highly sensitive and specific tumour marker for this. We shall present a case which typifies the presentation of MTC and discuss its relevance.
A 71-year-old gentleman of Italian descent was admitted in 2001 with left lower limb cellulitis. It was documented that he had an incidental goitre, that had been present for many years from which he was asymptomatic.
Subsequent Ultrasound revealed a 3.5x4.2x6.8 solitary Right nodule with minor calcification.
A Fine needle aspirate (FNA) although was blood stained, showed follicular cells and colloid with no evidence of malignancy.
Biochemical testing confirmed a euthyroid state, basal calcitonin level however was markedly elevated; 42 micrograms per litre (NR <0.08)
A Total thyroidectomy revealed an 84.3gram enlarged right lobe (9.5x7x4). Histology confirmed neoplastic C-cells & MTC.
DISCUSSION
Thyroid nodules have been investigated reporting 1385 & 469 patients respectively with nodular disease, MTC represented 15.7%, 26.7% of all differentiated cancers with an overall thyroid cancer prevalence of 3.1%, 3.19%. Serum CT was highly predictive of MTC but FNA was only diagnostic in 20-30% of cancers.
Although the prognosis of MTC is worse compared to other differentiated thyroid cancers, early pre-operative diagnosis together radical surgery has a high cure rate. As current imaging and FNA techniques have poor predictive value should we be routinely using calcitonin to screen older patients with long-standing nodular goitres?
References:
Pacini F et al., (1994). Routine measurement of serum calcitonin in nodular thyroid diseases allows the pre-operative diagnosis of unsuspected sporadic medullary thyroid carcinoma. Journal of Clinical Endocrinology and Metabolism, 78, 826-829
Rieu M, et al. (1995) Prevalence of sporadic medullary thyroid carcinoma: The importance of routine measurement of serum calcitonin in the diagnostic evaluation of thyroid nodules. Clinical Endocrinology. 42, 453-60.
Sheppard M.C. (1995) Should serum calcitonin be measured routinely in all patients with nodular thyroid disease? Commentary. Clinical Endocrinology. 42 451-2