Statement of the Problem: The biologic behavior and histopathological features of fibromatosis are intermediate between those of fibroma and fibrosarcoma.
Purpose: The aim of the present study was to determine useful histopathologic and immunohistochemical characteristics for the differentiation of these lesions.
Materials and Method: In this cross-sectional descriptive study, 40 specimens comprising 20 fibrosarcoma and 20 fibromatosis biopsies were selected. The histopathologic characteristics of these lesions were identified and immunohistochemical staining for Ki67 and β-catenin markers was performed. Sections were examined by light microscopy and positively stained cells were counted. Results were analyzed by SPSS 20 using Chi-square test, Mann-whitney test, and t-test (p< 0.05).
Results: Statistical significant differences were observed between fibromatosis and fibrosarcoma in terms of distribution frequency, mitotic rate, herringbone pattern, cellularity, overlapping of nuclei, mean Ki67 score, and atypia rate. The other features including age, gender, necrosis, clarity of nucleoli and mean β-catenin were not significantly different.
Conclusion: The present findings suggest the mitotic figures, Ki67, herringbone pattern, cellularity, and atypia are useful to differentiate fibromatosis from fibrosarcoma.