ABSTRACT
<p><b>OBJECTIVE</b>To study the histochemical staining in the diagnosis of osteosarcoma.</p><p><b>METHODS</b>To compare the effectiveness of picrosirius red, improved Ponceau trichrome and Masson trichrome staining methods on bone formation tissues in conventional osteosarcoma, paraosteal osteosarcoma, periosteal osteosarcoma, extraskeletal osteosarcoma, inflammatory myofibroblastic tumour, malignant fibrohistiocytoma, chondrosarcoma, fibrosis with ossification and calcification.</p><p><b>RESULTS</b>With modified Ponceau trichrome staining, bone formation tissues showed a homogenous, orange-red interblended with blue in color. From osteoid to mature bone the color changed from orange-red, light blue to dark blue. Fibrotic tissue was stained blue in color with striated appearance. Cartilage was not stained. Picrosirius red method gave bone formation tissues homogenous staining. Along with bone maturation, from osteoid tissue to mineralized bones, the color showed changes from light red, yellow, orange-red, red to dark purple. The cartilage demonstrated homogenous light red in color. Fibrous tissue stained red interblended with yellow in color, striated in shape. With Masson trichrome staining osteoid displayed pale blue and mineralized bone showed dark blue in color. Fibrotic tissue showed a striated blue staining.</p><p><b>CONCLUSION</b>The modified Ponceau trichrome and Picrosirius red staining methods are better than Masson trichrome to demonstrate bone formation tissue in osteosarcoma. The former two methods could be also used in study on bone formation.</p>