Triton tumors, malignant schwannomas with a rhabdomyoblastic component, are rare. This article reports the clinical course, therapeutic approach, and histopathologic aspects of three cases. Immunoperoxidase staining for the Schwann's cell marker S-100 protein and for the skeletal muscle proteins desmin, myosin, and myoglobin proved to be useful for diagnosis. The clinical histories of 24 previously reported cases are analyzed, and the therapeutic possibilities are discussed.
Cancer 58:1350-1356, 1986.
OR MANY YEARS, it has been recognized that malig-F nant schwannomas eventually contain metaplastic components, which are histologically interpreted as either benign or malignant.'-3 A special variant is the malignant schwannoma with rhabdomyoblastic elements, a so-called triton t ~m o r . ~, ~ Until recently, only 24 cases had been reported in the literature. Due to the extreme rarity of this tumor, the question arises whether it is warranted to distinguish this tumor type from other neurogenic tumors with mesenchymal components, i. e., metaplastic schwannomas.
We report three cases that were either referred to our Institute, or on which therapeutic advice was given. Their clinical history is presented, together with a detailed macroscopic and histologic description of the tumors. A survey of both clinical and pathologic literature data is given, and therapeutic recommendations are proposed.
Case Reports
Case 1
Clinical history: A 32-year-old man, who suffered from Von Recklinghausen's disease, was seen in March 1981 in a local hospital with a huge painful tumor in the right calf. Histologic