TRUE MALIGNANT HISTIOCYTOSIS DEVELOPED DURING CHEMOTHERAPY FOR MEDIASTINAL IMMATURE TERATOMA

We report an autopsy case of true malignant histiocytosis that develop ed during chemotherapy for mediastinal immature teratoma. The patient, vas a 14-year-old boy who exhibited hepatosplenomegaly while receiving chemotherapy for a mediastinal immature teratoma that had been resect ed 11 months before. The spleen and liver of the excisional biopsy dis played infiltration of multinucleated giant atypical cells with promin ent erythrophagia in massive aggregations. These atypical cells expres sed CD68, alpha 1-antitrypsin, alpha 1-antichymotrypsin, lysozyme, and vimentin, suggesting that the tumor cells may have been derived from macrophages, Immunocytochemistry showed p53 expression in the tumor ce lls of the malignant histiocytosis, as well as in the elements of the immature teratoma. Direct sequence analysis showed the p53 mutation in the tumor cells of the immature teratoma to be a mutation at codon 17 5 (exon 5), whereas the mutation in the malignant histiocytosis occurr ed at codon 285 (exon 8), ie, polyclonality was exhibited and these fe atures suggested that the malignant histiocytosis arose independently from the immature teratoma during the chemotherapy. Copyright (C) 1996 by W.B. Saunders Company