Malignant mesenchymoma of median nerve: combined nerve sheath sarcoma and liposarcoma.

A malignant mesenchymoma consisting of nerve sheath sarcoma and liposarcoma occurred in the right median nerve of a 29-year-old man who did not have stigmata of von Recklinghausen neurofibromatosis. It produced pain at the affected part, referred pain to the palm, and weakness of muscles supplied by branches of this nerve. The tumor was first excised 1 month after its initial manifestation, but recurred twice and eventually metastasized to the lung within 19 months. It is suggested that aberrant differentiation of the mesenchymal component of the neural crest, the ectomesenchymal structure, has created this combined sarcoma of nerve sheath and liposarcoma, forming a malignant mesenchymoma.