Ossifying fibromyxoid tumor of soft parts: Clinicopathologic, immunohistochemical and ultrastructural study of four cases

Abstract

Four cases of uncommon soft tissue tumors were investigated histopathologically. All of them consisted of fibrous and myxoid components, and mature bone showed shell-like characteristics. Histological features revealed these tumors were well circumscribed by a thick collagenous fibrous capsule and composed of uniform-sized fusiform cells with eosinophilic cytoplasm and a round or oval nucleus in the myxoid matrix. An incomplete shell of mature bone with lamellar structure was also observed at the periphery. Immunohistochemical and ultrastructural studies were performed. The major component of the proliferating cells in the tumors had positive staining for vimentin, S-100 protein, neuron-specific enolase and synaptophysin. The myxoid matrix was stained by alcian blue and was digested completely by pretreatment with hyaluronidase. Electron microscopy showed the cytoplasm contained dense-core granules measuring 100-200 nm and abundant filaments of an intermediate size. It is suggested that these uncommon tumors might be diagnosed as the 'ossifying fibromyxoid tumor of soft parts' previously described by Enzinger et al., which were derived from peripheral nerve sheath tumors such as neurofibroma and myxoid neurofibroma.

Ossifying Fibromyxoid Tumor: An Update

“…Evidence exists for a schwannian or neuronal differentiation but this has not been well proven. [18][19][20] Similarly, cartilaginous or myoepithelial differentiation was proposed by Enzinger et al 2 and Kilpatrick et al, 15 respectively. From these hypotheses, Graham et al 7 suggested a ''scrambled'' phenotype for these tumors.…”

Ossifying fibromyxoid tumor of the skin: A report of 2 cases with light microscopic, immunohistochemical, and electron microscopic characterization

“…In the majority of reported cases the tumor cells have shown positive immunoreaction for neural differentiation markers such as S-100 protein, neuronspecific enolase, glial fibrillary acidic protein, and Leu-7 (CD-57). 5,6,[9][10][11][12] In addition, in many cases the ultrastructural studies have demonstrated either abundant intermediate filaments or basal lamina that were partial and reduplicated, or both. [9][10][11][12] These facts mostly support neural or Schwannian differentiation.…”

Cytologic diagnosis of ossifying fibromyxoid tumor of soft tissue: A case report

“…Neural, cartilaginous, osteoblastic, myogenic, and fibroblasic origins have been postulated on the basis of immunochemistry and ultrastructural features. [1][2][3][4][5]9,11,12 The index case showed focal immunoreactivity for S-100 protein, suggesting a peripheral nerve sheath derivation.…”