Abstract

Fibrohistiocytic tumors are a diverse group of benign and malignant soft tissue lesions, including dermatofibroma, dermatofibrosarcomaprotuberans, and malignant fibrous histiocytoma. On the clinical point of view, the distinction between benign and malignant lesions and malignancy grading is far more important. Therefore, we investigated 23 fibrohistiocytic tumors, using PCNA (PC10) which was a useful marker of proliferating activity, to differentiate the benign lesions from the malignant and correlate with other prognostic factors including tumor necrosis. cellularity, histologic grade, and mitotic counts. The results obtained were as follows 1) Positive tumor cells were clearly identified by the characteristic diffuse or granular nuclear staining. 2) The number of PCNA-positive tumor cells were 2.16+/-2.39% in dermatofibroma, 16.12+/-7.38% in dermatofibrosacoma protuberans, and 28.02+/-17.47% in the malignant fibrous histiocytoma. The numbers of PCNA-positive tumor cells in the malignant lesions higher than in the benign (p<0.001). 3) Deep seated, large size (>5 cm) and recurred or metastatic cases of MFH were more the high PCNA index (more than 20%) than the low index (less than 20%) groups. 4) PCNA index in MFHs had positive correlation with the number of mitotic counts (r=0.7582, p<0.001), cellularity (r=0.5908, p<0.05) and histologic grade (r=0.4164, p<0.05). These results suggested that reactivity on PCNA might assist in the distinction between benign and malignant lesions in fibrohistiocytic tumors, and could be a useful prognostic factor in the patients with malignant fibrous histiocytoma.

• Keywords: Fibrohistiocytic tumors;PCN A;Mitoses;Prognosis