[Development of occult thyroid carcinoma].

Developmental features of 16 patients with occult thyroid carcinoma less than 1.0 cm in diameter as collected from our surgical specimens are described. They are classified into 3 types: non-capsular sclerosis, capsular non-sclerosis and non-capsular non-sclerosis types. Non-capsular non-sclerosis type is the developmental form at early stage. Tumors that grow rapidly and to which the host has a strong reactivity tend to change into the non-capsular sclerosis type. On the contrary, those which grow slowly to which the host is weak in reaction tend to change into the capsular non-sclerosis type. The relation between the histological classification and developmental form is discussed.