A histomorphological study on epiphyseal involvement caused by osteosarcoma around the knee joint in children

CAO Bin; WANG Zhen; GUO Zheng; LI Jing; LI Xiang-dong; FAN Hong-bin

doi:10.3969/j.issn.2095-252X.2016.02.013

Abstract：Objective To observe and analyze the forms and mechanism of osteosarcoma infringing on epiphyses and growth plate. Methods Specimens of osteosarcoma from 6 cases with osteosarcoma ( 2 were male and 4 were female ) were observed from 2013 to 2014 through optical microscope and micro-CT scans; the thickness and blood vessels of the growth plate were measured and a statistical analysis was performed. The average age of the patients was 11.5 years ( range: 7 - 14 years ). Four cases had distal femoral and 2 cases had proximal tibial osteosarcoma. All cases were of Enneking stage II B stage and San Julian type III. Results Histomorphometry: the mean thickness of the femur epiphyses with invasion was significantly lower than that without invasion in the same specimen ( 1.60 ± 1.03 ) mm, ( 1.03 ± 0.45 ) mm ( t = -3.17, P = 0.002 ). The mean thickness of the epiphyseal plate with invasion was significantly lower that without invasion in the same specimen [ No.3 specimen: ( 0.99 ±0.51 ) mm, ( 2.16 ± 0.50 ) mm; No.5 specimen: ( 0.78 ± 0.25 ) mm, ( 1.33 ± 0.41 ) mm ] ( t = 4.74, P = 0.001 ) ( t = 6.59, P =0.001 ). The number of blood vessels in areas with invasion was larger than that in areas without invasion in the same specimen [ No.3 specimen: ( 2.32 ± 1.32 ), ( 0.82 ± 0.85 ); No.5 specimen: ( 1.80 ± 1.19 ), ( 0.65 ± 0.67 ) ] ( t = 4.46, P = 0.000) ( t = 3.74, P = 0.001 ). There were four forms of changes in histomorphological observation: ( 1 ) the calcified layer of epiphyseal plate disappeared; ( 2 ) sieve-pore-like invasion; ( 3 ) dumbbell-like invasion; ( 4 ) the full-layer lysis. Conclusions The thickness of the epiphyseal plate becomes thin in areas of osteosarcoma invasion. Vascularizing reaction on the edge of the osteosarcoma tissue can accelerate the invasion. There is a diversity and selective perforation phenomenon in the process of damage to the epiphyseal plate. The epiphyseal plate has a barrier effect against the growth of osteosarcoma into the epiphyses.