An update on myofibromas and myofibromatosis affecting the oral regions with report of 24 new cases

STAT6 Reliably Distinguishes Solitary Fibrous Tumors from Myofibromas

“…Case specifics for 20 of our 24 MFs have been reported previously in the literature (Smith et al [14], cases 1-11, 13, 15-17, 19-21, 23, 24 are cases 1-20 in the present paper). Distinct nuclear positivity for STAT6 was lacking in all 24 MFs.…”

“…Since the discovery of NAB2/STAT6's role in SFT tumorigenesis [5][6][7] and the subsequent advent of STAT6 immunohistochemical marker, SFTs are more easily Table 2 Previously performed IHC results for 24 cases of MF; Cases 1-20 have been published prior in the literature [14] MF Previous IHC 1 αSMA+, desmin-, S100-, focal calponin+ 2 αSMA+, desmin-, vimentin+, CD34-, S100-3 αSMA+, desmin-, vimentin +, S100-4 αSMA+, MSA+, desmin-, S100-, CD34-5 αSMA+, MSA+, desmin-, vimentin +, S100-6 αSMA+, desmin-,S100-7 αSMA+, desmin-,S100-8 αSMA+, desmin-,S100-, CD34-9 αSMA+, MSA+, desmin-, H-caldesmon-, S100-10 αSMA+, MSA+, desmin-, vimentin+, AE1/3-, S100-11 αSMA+, desmin-,CD68-, AE1/3-, Cam 5.2-, S100-12 αSMA+, MSA+, desmin-, vimentin +, S100-13 αSMA+, desmin-,S100-, CD34-14 αSMA+, desmin-,S100-, CD68-15 αSMA+, MSA-, desmin-, S100-16 αSMA+, desmin-, CD34-, S100-, CD68-17 αSMA+, desmin-, CD34-, CD68-18 αSMA+, MSA+, desmin-, vimentin +, S100-, Factor 8-, CD68-19 αSMA+, desmin-,S100-, CD34-20 αSMA+, MSA+, desmin-,vimentin+ 21 αSMA+, MSA+, desmin-, CD68-, CD34-, S100-22 αSMA+, desmin-, S100-, CD68-23 αSMA+, desmin-, S100-24 αSMA+, S100- differentiated from other soft tissue tumors. While multiple researchers have reported the sensitivity and specificity of STAT6 expression in SFTs and its histopathologic mimickers [8][9][10][11][12][13], we were only able to find information about its expressivity in MFs for five cases in the literature: one case in a large series by Demicco et al (which reported negative STAT6 expressivity) [8] and four cases in a study by Yoshida et al [13].…”

“…Additionally, Demicco et al [8] reported that 4/17 cases of scar tissue expressed nuclear STAT6 antibody. Because trauma vaguely has been associated with MF [14], STAT6 expression in scar tissue further begs the question whether MFs may demonstrate STAT6 expression, as well. Some of the histopathologic overlap between SFTs and MFs includes the presence of ovoid to spindled cells, "staghorn"-like vessels, variable areas of collagenized or hyalinized stroma (also known as ropey collagen, keloidlike collagen, or amianthoid fibers), multinucleated giant cells, perinuclear clearing, densely hyalinized areas (also known as pseudochondroid areas) and mixed hyper-and paucicellular zones.…”

Odontogenic myxomas lack PDGFRB mutations reported in myofibromas

“…Myofibromas are benign tumors composed of myofibroblastic cells . One‐third of the lesions occur in the head and neck region, gnathic bones being occasionally affected . Solitary intra‐osseous myofibroma usually appears as a well‐defined unilocular or multilocular radiolucency in the posterior mandible of children and adolescents .…”

“…6 One-third of the lesions occur in the head and neck region, gnathic bones being occasionally affected. 7 Solitary intra-osseous myofibroma usually appears as a well-defined unilocular or multilocular radiolucency in the posterior mandible of children and adolescents. 6 It usually shows a histopathologic biphasic pattern composed of elongated spindle to polygonal cells in a fibromyxoid stroma interspersed with bands of collagen, forming a zoning effect, which may not be evident in some cases.…”