An autopsy case of so-called midline malignant reticulosis followed by extensive dissemination with immunohistochemical evidence for its T cell malignancy.

An autopsy case of malignant midline reticulosis (MMR) is reported. The patient, a 42-year-old Japanese male, died after a clinical course of 22 months. Autopsy revealed extensive infiltration of generalized organs by the tumor cells, suggesting that the disease was highly malignant in nature. Staining with monoclonal antibodies against T-cell surface antigens Leu 4 on frozen sections and UCHL1 on paraffin-embedded sections enabled us to examine the phenotype of the tumor cells with good morphological preservation and to verify the T cell nature of the tumor.