Inflammatory myofibroblastic tumor with HMGIC rearrangement.

Inflammatory pseudotumors or inflammatory myofibroblastic tumors (IMT) are lesions of extreme heterogeneity showing a highly variable mixture of bland-looking spindle cells, inflammatory cells, and collagen fibers. We describe our results of molecular cytogenetic and rapid amplification of cDNA ends (RACE-PCR) studies on an IMT characterized by a translocation involving 12q15. Chromosomal aberrations involving this region are very frequent among other benign tumors, such as lipomas, uterine leiomyomas, or pulmonary chondroid hamartomas. Recently, we have shown that, by these structural chromosomal aberrations, the HMGIC gene is affected. Fluorescence in situ hybridization (FISH) analysis and 3' RACE-PCR on cells of the present case of an inflammatory myofibroblastic tumor indicated an intragenic rearrangement of HMGIC, resulting in an aberrant transcript of that gene. Clonal cytogenetic aberrations have been described in very few cases of IMT. The results presented herein indicate that this case of IMT represents a true benign mesenchymal neoplasm associated with, or due to, a rearrangement of HMGIC.