Nerve sheath myxoma (neurothekeoma) arising in the oral cavity: histological and immunohistochemical features of 3 cases.

This report describes the histological and immunohistochemical characteristics of 3 cases of nerve sheath myxoma (NSM)/neurothekeoma arising in the oral cavity. Histopathologically, 3 distinct variants were observed based on the amount of myxoid matrix: classic/hypocellular, cellular, and mixed types. Immunohistochemically, all types expressed strong immunoreactivity to S-100 protein (3/3), NSE (neuron-specific enolase) (3/3), and NGFR (nerve growth factor receptor) (3/3), whereas all cases were negative for SMA (smooth muscle actin) and FVIII. The number of Ki-67 positive cells was less than 5% in all lesions confirming the slow growing characteristics of NSM. The results suggest that NSMs of the oral cavity are true peripheral nerve sheath tumors and show close relationship to schwannoma.

A male infant case of lipofibromatosis in the submental region exhibited the expression of the connective tissue growth factor.

PURPOSE: We encountered a case of lipofibromatosis in a 21-month-old male patient and examined its histopathologic properties. METHODS: We examined morphological aspects of the tumor and immunohistochemical patterns. RESULTS: Tumor proliferation was infiltrative, which did not show apparent encapsulation. Positive immunoreactivity was found for CD-34, CD-99, Ki-67, and connective tissue growth factor/CCN2 in the fibrous region, S-100 in the adipose region, and Notch1 stain was observed in the eccrine sweat gland cells juxtaposed to the tumor adipose tissue, but no reactivity for Bcl-2, alphaSMA, Notch 2-4, CCN1, and CCN3. CONCLUSIONS: The clinical process and immunohistochemical pattern of this case was consistent with the criteria of reported lipofibromatosis. Specific expression of CCN2 might be significant for the development of the tumor.