Common errors made by pathologists in the diagnosis of bone tumors

The potential of comparative genomic hybridization as a tool in the differential diagnosis of matrix-producing bone lesions

Matrix-producing bone lesions consist of a wide variety of benign and malignant conditions. With respect to morphology, an overlap exists between benign and malignant bone tumors that causes difficulties in the final determination of the tumor. This study was conducted to show the potential of comparative genomic hybridization as a tool in the differential diagnosis of matrix-producing bone lesions. Thirty benign bone tumors were evaluated by conventional comparative genomic hybridization. To test its diagnostic reliability, 5 additional cases were analyzed, all with differential diagnostic difficulties related to morphology and radiology. All were ultimately diagnosed as malignant sarcomas, and unbalanced alterations were detected. In contrast benign tumors or tumor-like lesions did not reveal any chromosomal alterations. Comparative genomic hybridization is a useful adjunct in the complicated differential diagnostic algorithms of matrix-producing bone tumors.

Chronic osteomyelitis mimicking sarcoma

This report describes a rare case of chronic osteomyelitis in a 60 year old man mimicking a soft tissue sarcoma. Chronic osteomyelitis is an infrequent cause of a soft tissue mass and is usually diagnosed clinically by a combination of radiology and microbiology. Rarely, COM can mimic a primary bony neoplasm, but this is the first reported case where it mimicked a soft tissue sarcoma. The clinical, radiological, and histological appearances of this case will be discussed.

Cytophotometric studies of the nuclear DNA content in cartilaginous tumors

The histopathological differentiation between chondromas and low-grade malignant chondrosarcomas can be difficult. For this reason we studied in 37 different cartilaginous tumors the mitotic index and the Feulgen DNA content using a scanning-integration cytophotometric technique. In 23 chondromas the Feulgen DNA content was diploid and showed a unimodal normal distribution. The number of mitoses was 0--0, 5%. The nuclei of a chondroblastoma were also diploid and the Feulgen DNA content was normally distributed. The mitotic index was 1% and few tetraploid nuclei, which were probably G2 nuclei, were observed. In two chondromyxoid fibromas, the average Feulgen DNA content was diploid and normally distributed. Several tetraploid nuclei were noted. The mitotic index was respectively 0.25% and 1.75%. Recurrence was noted in the first case. The Feulgen DNA content and mitotic index were clearly different in the chondrosarcomas. The distribution of the DNA content was bimodal or unimodal in low-grade chondrosarcomas. The mitotic index was less than 3%. In high-grade malignant chondrosarcomas, the histograms were broad unimodal or aneuploid. The mitotic index was above 5%.