Consistent t(1;10) with rearrangements of TGFBR3 and MGEA5 in both myxoinflammatory fibroblastic sarcoma and hemosiderotic fibrolipomatous tumor.

Despite their shared predilection for superficial soft tissue of distal extremities and frequent local recurrences, myxoinflammatory fibroblastic sarcoma (MIFS) and hemosiderotic fibrolipomatous tumor (HFLT) have distinct morphologic appearances. Recent studies have identified an identical t(1;10)(p22;q24) in five cases of MIFS and two of HFLT, as well as common amplifications on 3p11-12. To investigate further their potential relationship and to determine the incidence of t(1;10) in a larger cohort, we subjected seven MIFS, 14 HFLT, and three cases with mixed morphology, to molecular and cytogenetic analysis. Fluorescence in situ hybridization (FISH) analysis for rearrangements of TGFBR3 on 1p22 and of MGEA5 on 10q24 was performed in all cases, whereas the status of VGLL3 gene amplification on 3p12.1 was investigated in 12 cases. Conventional karyotyping was performed in one HFLT and two cases with mixed MIFS/HFLT histology. Overall 83% of cases showed rearrangements in both TGFBR3 and MGEA5. All three cases with mixed features of MIFS and HFLT were positive. Cytogenetic analysis performed in three cases confirmed an unbalanced der(10)t(1;10)(p22;q24). VGLL3 gene amplification was noted in 10/12 cases of both histologies. The high incidence of t(1;10) in MIFS and HFLT reinforces a shared pathogenetic relationship. Furthermore, the co-existence of both components either synchronously or metachronously in a primary or subsequent recurrence, suggest either different morphologic variants or different levels of tumor progression of a single biologic entity. FISH analysis for TGFBR3 and MGEA5 rearrangements can be applied as a reliable diagnostic molecular test when confronted with limited material or a challenging diagnosis.