Intracytoplasmic lysozyme in malignant hematologic disorders: an immunoperoxidase study.

Intracytoplasmic lysozyme was studied by the peroxidase antiperoxidase (PAP) and protein A-peroxidase methods in 130 cases of various myeloproliferative and lymphoproliferative disorders and 21 lymph nodes and bone marrow metastases from solid primary tumors. This marker, which can be identified in formalin or Zenker-fixed tissues, as well as in peripheral blood and bone marrow smears, proved useful to distinguish malignant myeloid and histiocytic tumors from malignant lymphoid and undifferentiated epithelial metastases. The diagnostic application of these findings are discussed.