Comparison of DNA ploidy, histologic, and immunohistochemical findings with clinical outcome in inflammatory myofibroblastic tumors

Inflammatory myofibroblastic tumors (IMTs) are uncommon spindle cell prolif erations that occur in the viscera and soft tissue of children and young ad ults. Their biologic potential is indeterminate: 25% of IMTs recur, and rar e examples undergo malignant transformation (MT). This study investigates h istologic features, DNA ploidy, and expression of apoptotic regulatory and oncogenic proteins in IMTs in an attempt to identify those deviances that m ight correlate with aggressive behavior or MT. Twenty-four formalin-fixed, paraffin-embedded IMTs for which clinical outcome was known were evaluated for cellularity, cytologic atypia, mitoses, ganglion-like cells, inflammato ry infiltrate, DNA ploidy by now cytometric examination, and bar, bcl-2, p5 3, and c-myc expression by immunohistochemical analysis. Sixteen (67%) of t he IMTs did not recur, 6 (25%) recurred, and 2 (8%) underwent MT. Cellular atypia was observed in 69% of the cases without recurrence, 100% with recur rence, and 100% with MT. Ganglion-like cells were present in 56, 100, and 1 00% of the IMTs without recurrence, with recurrence, and with MT, respectiv ely. There was no difference in the degree of cellularity, mitoses, or infl ammatory infiltrate among the outcome groups. All of the tumors expressed b ar, and none expressed c-myc. Two (8%) were immunoreactive for p53, one of which recurred and one of which underwent MT. bcl-2 expression was observed in 9 (37%) of the IMTs, with no difference among the three groups. Two IMT s were aneuploid, one of which underwent MT. Neither morphologic evaluation for cellularity, mitosis, or inflammatory infiltrate nor expression of bar or c-myc were useful for prediction of clinical outcome. The combination o f atypia, ganglion-like cells, p53 expression and DNA ploidy analysis, howe ver, might be useful to identify IMTs that might undergo MT or pursue a mor e aggressive clinical course with recurrences.