Cause:Neoplasia
Pathophys:Neoplasia of parafollicular thyroid cells, multicentric origin (Nejm 1973;289:437); characteristically produce CEA, and/or thyrocalcitonin, and/or serotonin, and other vasoactive substances; RET proto-oncogene type progresses through C-cell hyperplasia to cancer starting at age 3-4 yr so that by age 20 yr, nearly all have Ca.
May be sporadic, familial, or associated with multiple endocrine neoplasias (MEN) type II A + B (Sipple's syndrome): bilateral pheochromocytomas, gi mucosal neuromas (in 10%—Nejm 1976;295:1287), parathyroid adenomas (10%); inherited with autosomal dominant pattern w RET proto-oncogene (Nejm 2003;349:1517; 1996;335:947; Jama 1995;274:1149)
Local metastases; pheochromocytoma (30%); secondary Cushing's from ACTH; hyperparathyroidism (Nejm 1968;279:279) in MEN type II
Lab:
Chem:Thyrocalcitonin >28 pm/L (Ann IM 2005;143:926); CEA elevated
Path:Thyroid bx shows clumps of parafollicular cells surrounded by collagen ("amyloid struma")
Xray:Thyroid scan shows a cold mass, starts in upper poles. Plain films may show calcified metastases, which can look like old tbc even with liver mets
Rx:
Prevent cancer deaths in MEN II families w annual calcitonin stimulation tests (Nejm 1988;318:479); perhaps prophylactic thyroidectomies in genetically identified MEA IIA children (Nejm 2005;353:1105).
Surgery with follow-up thyrocalcitonin/CEA levels as markers of residual tumor (Nejm 1974;290:1035)
Chemotherapy w adriamycin (Nejm 1974;290:193)