AN IMMUNOHISTOCHEMICAL STUDY OF P53 PROTEIN EXPRESSION IN CLASSICAL KAPOSIS-SARCOMA

The present study was performed to determine the frequency of p53 prot ein immunoreactivity in classical Kaposi's sarcoma (KS) as a whole and in relation to the histological subtypes which are considered to corr espond to the developmental stages of the tumor. The accumulation of p 53 protein was studied immunohistochemically using monoclonal antibody BP53-12 on formalin-fixed paraffin-embedded sections of 36 KS lesions , of which 14 were classified histologically as early type and 22 as s pindle-cell or mixed type. No positive immunoreactivity was detected i n any of the 14 early-type lesions. Among the 22 spindle-cell and mixe d variants, positive staining was detected in 5-10% of the tumor cells in one lesion, 1-5% of the cells in six lesions, and in <1% of the ce lls in two lesions. These very small percentages of positively stained cells in less than half of the cases of the spindle-cell and mixed va riants do not support a significant role for p53 in tumor progression and evolution in KS.