[Organ specificity and common factors in latent tumors]

Materials displaying latent tumors were obtained from autopsy cases and from surgically removed organs at our hospital during the past 20 years. Organ specificity and the common factors of these latent tumors indicated the following: a high incidence of latent tumors was found in the small organs and/or endocrine organs (prostate, thyroid, pancreas). In addition, it was found that these tumorous organs are of sufficient interest for clinicopathologic study (stomach, esophagus). Latent tumors show an increasing tendency to manifestation at an advanced age. Further, shade of difference between females and males has been noted in comparing clinically manifested tumors. Also latent tumors occasionally coexist with multiple primary neoplasms in the same and indifferent organs. The histological characteristics of latent tumors is frequently associated with thickened capsules and fibrosis. It has been speculated that the appearances of a reaction are local autoimmune mechanisms and the hosts suppressive effects against the proliferation of tumors. The biological behaviour of latent and clinical tumors should be considered different.