[Apudomas].

Apudomas, i.e. tumours deriving from apud system cells, comprise already known forms located in widely different organs at considerable distances one from the other. They present great cytochemical, biochemical and ultrastructural similarities and possess a common derivation in the neuroectodermal cells of the neural crest. They thus form part of that tumour group known as neurolophomas. They are also responsible for typical clinical pictures connected with the production of hormone-type substances, and are classified among multiple endocrine adenomatoses and in the ectopic hormone syndromes.