medullary carcinoma of thyroid

medullary carcinoma of thyroid

Atypical carcinoma, compact small cell carcinoma, solid carcinoma, of thyroid A tumor comprising 3-10% of thyroid CAs, arising in the C–parafollicular–cells of ultimobranchial cleft–neural crest origin Clinical Tumors metastasize to cervical lymph nodes, mediastinum, lungs, liver, bone, adrenal glands; ↑ calcitonin causes hypercalcemia, HTN, paraneoplastic syndromes–eg, Cushing syndrome and neuromas; MCTs may produce ACTH-like substance, biogenic amines, CEA, corticotropin-releasing factor, NGF, prolactin-releasing hormone, PGs, melanin-stimulating hormone, histaminase, β-endorphin, 5-hydroxytryptamine, serotonin, somatostatin, thyroglobulin Risk factors RT to head or neck, family Hx of multiple endocrine neoplasia, Hx of pheochromocytoma, mucosal neuromas, hyperparathyroidism Treatment Total thyroidectomy Prognosis 70-80% 5-yr survival; sporadic MCT has a 50% 10-yr mortality–10- and 20-yr survival is 63% and 44% respectively; in contrast, papillary thyroid carcinoma has 95% 5- and 10-yr survival. See Anaplastic carcinoma of thyroid, Follicular tumor of thyroid, Papillary carcinoma of thyroid, Thyroid lymphoma.

Medullary carcinoma of thyroid–clinical forms

Sporadic MCT 80-90% of cases, mean age of onset 45, presenting as a solitary 'cold'–by thyroid scan–nodule variably accompanied by intractable diarrhea and Cushing's syndrome

Familial MCT 10-20% of cases–in one study with ≈ 23.5 years follow-up 11% were familial, mean age of onset 35, presenting as a multifocal and bilateral mass, accompanied by C-cell hyperplasia of residual thyroid tissue; familial MCT is often AD and associated with multiple endocrine adenomatosis, usually type II–which has a germline abnormality on chromosome 10, an earlier age of onset, and is often bilateral, or occasionally type III–IIb, less common, but more aggressive and rarely a non-aggressive form of MCT that is not associated with other neural or endocrine lesions