Abstract

A malignant schwannoma is a relatively rare malignant neoplasm of nerve sheath origin that locally infiltrates and also metastasizes, the intercellular matrix containing collagen and mucin. The diagnosis of malignant schwannoma should be primacy consideration in only two following circumstances in the presence of a malignant tumor of soft tissue composed of spindle cells : 1) when the tumor develops in patient with von Recklinghausen’s disease, and 2) When tumor is obviously arising within the anatomic compartment of a major nerve or in continuity with a unquestionable neurofibroma. In the usual case, a plexiform neurofibroma is closely associated with a malignant schwannoma. According to some investigators, notably Hosoi. the incidence of malignant transformation of neurofibromatasis is as high as 13%. The case reported herein is an example of malignant schwannoma to meet the above criteria satisfactorily, grossly as well as microscopically. This 42-year-old widow who is known to have von Recklinghausen’s neurofibromatosis for the past 10 years has developed a gradually growing subcutaneous tumor in the volar surface of the left forearm with radiating and tingling pain in the 2nd and 3rd finger’s of the left hand. The tumor had recurred three times artier local excisions. This time it recurred 7 months after last excision. A disarticulated left forearm was sent to laboratory which demonstrated the tumor to be arising from the neurofibromatous median nerve and composed of large spindle cells with whorl formation and organoid pattern. Individual cells show irregular hyperchromatic nuclei and frequent mitotic figures. About 2 months after amputation, a rapidly growing tumor on the left shoulder which was diagnosed as neurofibrosarcoma elsewhere. And chest X-ray shows a diffuse radio-opaque shadow on the right lung field which is suspected of a metastatic lesion. Malignant schwannoma recurs as a rule and metastasizes at a late stage to fun by blood stream and rarely to regional lymph node and centripedal metastasis to proximal nerve. The treatment of choice is one stage radical surgery. And excisional biopsy for diagnostic or therapeutic purpose is condemned. The prognosis usually is Poor.