Low-grade Myofibroblasts Sarcomas Of The Maxilla

Aims:Low-grade myofibroblastic sarcoma (LGMS) is a distinct mesenchymal entity of myofibroblastic malignancies, which occurs at a variety of sites, but has a predilection for the head and neck region. Among the two maxillary sarcomas analyzed in the present study, one was misdiagnosed as inflammatory myofibroblastic tumor (IMT) during preoperative excision biopsy and presented with a different immunophenotype on recurrence.Methods:Representative paraffin blocks from formalin-fixed tissues were selected from each patient (designated as Case1and Case2). Immunohistochemical studies were performed on3μm-thick sections, using primary antibodies that included a-SMA, MSA, desmin, vimentin, calponin, h-caldesmon, fibronectin, cytokeratin, CD34, s-100protein, ALK, EMA and Ki-67. Immunohistochemistry was performed using the streptavidin-biotin peroxidase complex method.Results:Tumor cells were positive for vimentin and fibronectin, and negative for S-100protein, CD34, EMA, h-caldesmon, ALK, MSA and calponin in the two maxillary LGMS (including the recurrent lesion). Tumor cells in Case1demonstrated positive staining for a-SMA protein and negative staining for desmin. Tumor cells from the primary lesion in Case2presented with negative staining for a-SMA and positive staining for desmin of the primary lesion, while the recurrent lesion cells were a-SMA-positive and desmin-negative.Conclusion:We hypothesize that LGMS that presents itself with alterations in their immunoprofile takes on a relatively worse prognosis.