The malignant schwannoma is the primary malignant tumor, which originating from the schwann cell. The incidence is markedly rare. This malignancy is not uncommonly accompanied by von Recklinghausen's disease with the worse prognosis. Although lung is the common site of the distant metastasis, bone metastasis is extremely rare. Histologically this malignancy is composed mainly of spindle cells, but occasionally the rare type, called malignant epitheloid schwannoma, which is composed of many epitheloid cells and scant spindle cells, is found as in this case. It is difficult to differentiate the malignant epitheloid schwannoma with the amelanotic melanoma histologically. The authors have experienced one case (16 years old female) of malignant epitheloid schwannoma originating from the scalp on the occipital area and metastasizing to the proximal part of the right humerus.
Humerus ; Incidence ; Lung ; Melanoma, Amelanotic ; Neoplasm Metastasis ; Neurilemmoma ; Neurofibromatosis 1 ; Prognosis ; Scalp