The loss of histidine decarboxilase activity of plasma cells infiltrating the skin in a case of therapy resistant multiple myeloma. A common characteristic of epidermoinvasive malignant B-cell

J Varkonyi MD PhD^a, K Szocs, A Vereczkei MD PhD, MD Karadi, DSCI , Z Sapi MD, DSCI ^b, M Marschalko MD PhD^a, D Kovacs PhD^c, A Falus, DSCI

^aSemmelweis University Medical School, Budapest, Hungary, ^bDepartment of Pathology, St. Juhns's Hospital, Budapest, Hungary, ^cKenezy Gyula County Hospital, Debrecen, Hungary

Authors represent the case of a 70-year old women with therapy resistant multiple myeloma who developed plasma cell skin infiltrates in the course of the disease. The skin infiltrating plasma cells didn’t show histidine decarboxylase activity in comparison to what was found in bone marrow myeloma cells and reactive plasma cells in another skin sample. In the time of tissue invasion the monoclonal protein production, characteristic for the disease became undetectable. Loss of histidine decarboxylase activity in the infiltrating cells and also the loss of ability for monoclonal protein production serve further evidences of disease transformation to a more malignant form. Authors found identical enzyme changes in two other patients with B-cell chronic lymphocytic leukemia what seems not to be incidental finding but a characteristic phenomenon of epidermoinvasive malignant B-cells.

Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Nice, France; February 7 - 10, 2004; in oral session 893 (Molecular pathology - Part I).