p53 Protein and Proliferating Cell Nuclear Antigen (PCNA) Expression in Small Round Cell Tumors of Bone and Adjacent Soft Tissue A Study of 60 Cases

Sixty small cell tumors of bone and adjacent soft tissue were studied in an attempt to define the incidence of immunohistochemically detectable p53 protein and cor-relate these findings with the results of proliferating cell nuclear antigen (PCNA) immunohistochemical staining and mitotic counts. All of the lesions had been for-malin-fixed and paraffin-embedded; half were subjected to decalcification prior to processing. The study population included 12 Ewing’s sarcomas of bone, 3 atypical Ewing’s sarcomas of bone, 3 primitive neuroectodermal tumors of bone, 11 Askin tumors of the thoracopulmonary region, 11 small cell osteosarcomas of bone, 10 mesenchymal chondrosarcomas of bone, and 10 malignant lymphomas involving bone. The patients ranged in age at the time of presentation from 17 to 67 years. Overall, the incidence of p53 positivity was extremely low in these lesions, irre-spective of tumor type. Positive nuclear staining with an antibody to p53 was found in none of the 12 Ewing’s sarcomas, none of the 3 atypical Ewing’s sarcomas, none of the 3 primitive neuroectodermal tumors of bone, 1 of the 11 Askin tumors of the thoracopulmonary region (1.5 % of tumor cells positive), 1 of the 11 small cel