[Clinicopathological study of twenty-two cases of benign chondroblastoma (author's transl)]

Benign chondroblastoma, a rare bone tumor clinically and histologically resembles giant cell tumor. We have experienced twenty-two cases of histologically confirmed benign chondroblastoma over the 25 year period from 1952 to 1978. The age of the patients ranged from 10 to 46 years, with an average of 20 years. Fifteen cases were in the second decade. Males were predominant to females with a ratio of 2.7:1. Location of the tumor varied widely. The tumor was located in the long bones in 18 out of 22 and limited to the epiphysis in 15. Detailed histological examination in twelve cases with hematoxylin-eosin, alucian blue, toluidine blue, silver impregnation and safranin-O staining, revealed positive staining with alucian blue and PAS. PAS positive granules wee found within cytoplasm and identified as glycogen granules by electron microscopy. However, metachromasia was not always positive and none of these cases stained positive with safranin-O. Rich reticulin fibers encircled each tumor cell and each group of cells. Electronmicroscopic study of 4 cases revealed two types of giant cells. The cell membrane had many microvilli-like protrusions, and the nuclei of the tumor cells were irregular in appearance and had large indentations. Sometimes many fine filaments and electron dense fine granules were observed in intercellular chondroid space. Morphological study of cultured cells was done in two cases. Morphology of these tumor cells proved to be different from fibroblasts, cultured chondrocytes and macrophages. Tumor cells moved rapidly and had undulating membranes at the pseudopodia. From these findings, we speculated that the origin of the benign chondroblastoma cell may be histiocytic cells. Surgical treatment of this tumor was carried out as follows. Curettage was performed in 16 cases, with bone graft in 15, resection 4 and amputation in two. Recurrence was noted on two cases, although no further recurrence occurred after reoperations for nine and twelve years respectively.