Malignant histiocytosis associated with autoimmune thrombocytopenia

Xanthoma disseminatum with hepatic involvement in a child

Xanthoma disseminatum is a rare, usually self-healing dermatologic disease of unknown etiology. Involvement of other organs and tissues including bone marrow, bone, and brain may be seen rarely in children. However, to date, hepatic involvement has not been reported. We describe a child with xanthoma disseminatum who had hepatic involvement, and discuss his course and treatment with steroid and azathioprine.

Monocyte/Macrophage-specific marker CD163+ histiocytic sarcoma: case report with clinical, morphologic, immunohistochemical, and molecular genetic studies

We report a case of a very rare disorder, histiocytic sarcoma, from a review of our autopsy cases. The neoplastic cells that proliferated in organs throughout the body were large cells containing eosinophilic cytoplasm and pleomorphic nuclei with prominent nucleoli. In the bone marrow, erythrophagocytosis by neoplastic cells was observed. The neoplastic cells were positive not only for lysozymes and CD68 (KP-1, PG-M1, and Ki-M1P) but also for a monocyte/macrophage-specific marker, CD163. In contrast, the results of tests for markers of myeloid cells, lymphoid cells, and epithelial cells were all negative. In a polymerase chain reaction study of paraffin-embedded tissues, analyses for the rearrangement of immunoglobulin heavy chain and T-cell receptor-gamma genes were negative. The current World Health Organization diagnostic criteria for histiocytic sarcoma regard immunohistochemical investigation as crucial. In this regard, the highly specific positivity for CD163 in this patient indicates that immunohistochemical staining of CD163 is very useful for the diagnosis of histiocytic sarcoma.

True malignant histiocytosis

OBJECTIVE

To attempt to distinguish cases of true malignant histiocytosis from the clinical syndromes of so-called malignant histiocytosis with use of recent methods.

DESIGN

We retrospectively studied the laboratory data and clinical course of Mayo patients who had clinical syndromes of so-called malignant histiocytosis and reviewed available paraffin-embedded tissue specimens to identify the nature of the malignant cells.

MATERIAL AND METHODS

After elimination of cases of infection-associated hemophagocytic syndrome, we reviewed and studied seven cases of so-called malignant histiocytosis in patients who had undergone assessment at Mayo Clinic Rochester between 1973 and 1993. We identified histiocytes by using current morphologic, cytochemical, and immunohistochemical methods. The clonal nature of the malignant cells was identified with morphologic, cytogenetic, and molecular genetic studies.

RESULTS

Only one of the seven cases had a true histiocytic origin. The malignant cells were T cells in three other cases (the cells were also CD30+ in two cases), CD30+ cells only in one case, epithelial cells in one case, and an undetermined cell type (stained positively only with antitrypsin) in one case.

CONCLUSION

True malignant histiocytosis is an exceedingly rare disease, and only a few reports have clearly identified the histiocytic origin of the malignant cells. Previously, the lack of monoclonal antibodies specific to histiocytes and the absence of techniques for performing molecular genetic studies on paraffin-embedded tissue prevented the study of such cases. With newer techniques cases of true malignant histiocytosis can now be identified.