Mast cells density in fibrotic capsule of enchondroma and well-differentiated chondrosarcoma: a method for histopathologic differentiation

An enchondroma is a benign and a well-differentiated chondrosarcoma is an invasive chondroid tumor with high recurrence potential. In spite of biologic differences, these two tumors have very similar histopathologic appearance. It has been shown that the biologic nature of the connective tissue around benign and malignant tumors varies in the number of mast cells. The aim of this study was to study the histopathologic distinction of enchondroma and well-differentiated chondrosarcoma using the density of the mast cells in fibrotic capsule. Twelve enchondroma and 15 well-differentiated chondrosarcoma were collected from Pathology department of Cancer Institute and Central Pathology department of Imam Khomeini Hospital in Tehran. 3 micron paraffin embedded tissue sections were stained by toluidine blue for mast cells counting. Mast cells were counted in fibrous capsule of all cases. Mast cells counts were accomplished in 10 high power fields .The average number of mast cells in 10HPF was determined as an index for each lesion. Mann-Whitney U test was used for statistical analysis. Mean index in enchondroma and well-differentiated chondrosarcoma groups were 0.1 +/- 0.12 and 0.31 +/- 0.33 respectively, showing a significant difference between number of mast cells in the fibrotic capsule in these two lesions [p=0.028]. Comparison of the corresponding points in ROC curve, showed a cut-off point = 0.15, with positive predictive value of 61%, negative predictive value 71%, specificity of 33.3% and sensitivity of 66.7%, [p=0.025]. Average density of the mast cells in the surrounding fibrotic capsules of enchondroma and well-differentiated chondrosarcoma along with other criterions, could be a beneficial factor for histologically differentiation between these two lesions

Comparison of bovine fascia and ''evolution" membrane in regeneration on parietal bone of rabbit

Use of bone substitutes and membranes is an increasingly popular technique to stimulate new bone formation for treatment of orthopedic disorders resulting from bone defects and deficits and has been accepted as a standard treatment modality. Considering the use of bovine fascia as an absorbable membrane, this study compared the rate of bone formation after using bovine fascia and a collagen membrane [Evolution] in a rabbit model. In this experimental study 4 male New Zealand rabbits with a mean weight of 2.5 kg were used. After anesthetizing, three bone defects with 8 mm diameter were created bicortically in the parietal bone of the animals. Two defects were covered randomly with bovine fascia or ''Evolution" membrane and one remained uncovered as the control. After 12 weeks the rabbits were sacrificed and the bone formation was determined histologically. The bone type, inflammation, necrosis and fibrosis were also compared in the three groups and the data was analyzed using Jonckheere-Terpstra test. Out of 4 bovine fascia specimens, half of them showed no bone formation, one showed 33%-36% bone formation and the remaining one showed more than 66% bone formation. Half of the defects covered by "Evolution" membrane showed no bone formation, and the remaining two showed bone formation of less than 33%. In the control group, half showed no bone formation, and the remainder of the samples showed bone formation of more than 66%. No statistically significant difference in terms of bone formation was found between the three groups. From the aspect of type of bone, bovine fascia samples showed the formation of woven and lamellar bone each in one sample, two specimens in "Evolution" membrane group showed lamellar bone and two specimens in the control group showed woven bone formation. The three groups had no significant differences with regard to bone type, inflammation, necrosis or fibrosis. The present study showed that bone regeneration occurred in the defects covered with bovine fascia, "Evolution" membrane and control group was similar without any significant difference. Thus, the bovine fascia can be used as an alternative for "Evolution" membrane to induce bone formation. However, neither bovine fascia nor the "Evolution" membrane could facilitate bone formation as well as the control group