Indeterminate-cell histiocytosis: Immunophenotypic and cytogenetic findings in an infant

Background. The authors report the immunohistochemical, ultrastructural, an d cytogenetic findings in a case of malignant histiocytic proliferation in an infant. Procedure The patient presented initially with bone lesions with out skin or systemic involvement. Multiple biopsies were studied extensivel y by immunohistochemistry and electron microscopy. Cytogenetic studies of c ell cultures supplemented with granulocyte-monocyte colony stimulating fact or (GM-CSF) were also performed. Results. Morphologically, the cells resemb led Langerhans cells, although with greater pleomorphism, as evinced by cel ls with usual polylobated nuclei. These cells expressed markers for macroph ages and antigen presenting cells and were CD1a- and S-100-positive, but la cked Birbeck granules. The cells grown in culture supplemented with CM-CSF showed a unique combination of numerical and structural abnormalities affec ting chromosomes 1, 6, 8, and 10. The disease followed a malignant course l eading to the patient's demise despite aggressive chemotherapy and bone mar row transplant. Conclusions. The findings suggest a malignant hematopoietic stem-cell neoplasm with a capacity for macrophage or dendritic-cell differ entiation. Morphology and immunophenotypic features place this neoplasm wit hin the group recently conceptualized as indeterminate-cell histiocytosis. MEd. Pediatr. Oncol. 32:250-254, 1999. (C) 1999 Wiley-Liss, Inc.