[Post-therapeutic development of small cell epitheliomas to malpighian epitheliomas, or initially composite forms? Apropos of 3 cases, review of the literature].

Three cases of transformation of small cell carcinomas into squamous cell cancer after chemotherapy are reported. A review of the literature shows that about 7% of small cell carcinomas are associated to different histological types of cancer before treatment. Such an association is found in about 25% of the cases after chemotherapy. Recent biochemical and ultrastructural approaches have led to new concepts concerning the histogenesis of lung cancer. The unicyst theory suggested by some authors could explain the therapy-induced maturation of undifferentiated small cell carcinoma.