[The origin of midline malignant reticulosis]

On the basis of light microscope examination and clinical pathological retrospective analysis, 32 cases of highly suspected midline malignant reticulosis (MMR) were investigated for immunophenotype expression (UCHL-1 for T lymphocytes and L26 for B cells) and TCR beta or IgH gene rearrangement. Scrapped tissue from stained and unstained formalin-fixed paraffin-embedded tissue sections were used for PCR gene rearrangement analysis. The results showed: Atypical lymphoid cells (ALC) in 24 cases of MMR expressed UCHL-1 marker, only one case was positive for L26. UCHL-1 and L26 positive cells often coexisted in the lesion. TCR and IgH gene rearrangement analysis using scrapped tissue showed 17 cases to be positive for TCR beta gene, which included 12 for UCHL-1 positive and 5 for UCHL-1 negative. The only one which was L26 positive showed IgH gene rearrangement. The gene rearrangement analysis further demonstrated that most MMR are T lymphocyte neoplastic proliferating disorder (extranodal T lymphoma) and could also originate from B lymphocytes.