Carcinoma lobulare in situ B in monozygotic twins.

Some form of predisposition to breast cancer can be inherited, but it is not known whether the same applies to precancerous lesions of the breast. We are reporting on an identical incidence of carcinoma lobulare in situ type B in monozygotic twins. The case report illustrates that in identical twins the environment is usually more similar than in the general population so it is difficult to determine the hereditary component in the manifestation of a specific histologic trait. The observation may support the hypothesis that there is not only a high incidence of multicentric disease in both breasts of one person, but in the breasts of identical twin sisters too.