[Sipple's syndrome: type II endocrine polyneoplasia (author's transl)].

Sipple's syndrome is a generally familial polyneoplastic affection associating a medullary thyroid cancer and a pheochromocytoma. The overall picture of the syndrome has, in fact, become larger now that it is known that there is previous hyperplasia of thyroid C cells and chromaffin cells in relation to neoplasms. Increase in plasma thyrocalcitonin levels is the best indicator of medullary cancer, and the discovery of this hormone in pheochromocytomas has shown the secretory origin of the two tumors, the cells of which have a common embryological origin in the neural crest. Sipple's syndrome is often associated with hyperparathyroidism, hyperplasia without adenoma (endocrine polyneoplasia type II a), or phacomatosis and a dystrophic condition (type II b or III). The authors discuss the nosology of the syndrome and its relation to the diffuse endocrine and APUD systems.