INFLAMMATORY MYOFIBROBLASTIC TUMOR OF BONE - REPORT OF 2 CASES WITH EVIDENCE OF CLONAL CHROMOSOMAL CHANGES

Inflammatory myofibroblastic tumor (inflammatory pseudotumor) is a pse udosarcomatous lesion that is recognized with increasing frequency in various anatomic locations. However, this lesion has not been previous ly reported in bone. We report on two cases of inflammatory myofibrobl astic tumor occurring in bone in young adults. Both tumors presented a s slightly painful, osteolytic, and well-delineated lesions of the dis tal femur, with a hyperintense signal on T-2-weighted magnetic resonan ce imaging. The patients had an uneventful recovery after curettage. T he follow-up time was 11 months for both patients, and no recurrence w as noted. On histologic examination, the lesions were characterized by collagen-rich and generally poorly cellular tissue containing spindle d to plump (myo)fibroblast-like cells and a variable admixture of infl ammatory cells. Focal calcifications and reactive bone formation were present. Clonal, albeit different, chromosomal changes were found in b oth cases (47,XY,-9,-12,add(21)(q21),+der(?)t(?;9)(?;q11), +mar,+r and 47, XY, +r/47. idem, add(12)(p13)). The present and other reported cy togenetic findings suggest that inflammatory myofibroblastic tumors co uld well be neoplastic.