Malignant Schwannoma in von Recklinghausen's Disease: A Case Showing Glandular and Rhabdomyoblastic Differentiation

Unusual tissue elements may be encountered occasionally in malignant nerve sheath tumors. For instance, cartilaginous differentiation is seen in 11 %, the foci of rhabdomyosarcoma in 15%, and areas showing bone formation may be seen in 4% of these tumors (Warner et a/., 1983). Rarely is more than one type of heterologous element discovered in the same tumor (Agostino et a/., 1963). Besides the above-mentioned histologic types, a glandular component can be seen, and in such cases the term glandular schwannoma has been applied. This is an exceedingly rare occurrence, and, to our knowledge, only 10 such instances have been reported to date. The histogenesis of these unusual variants of nerve sheath tumor is controversial. We report herein a malignant nerve sheath tumor that shows heterologous elements comprised of true and pseudoglandular structure as well as rhabdomyosarcomatous element. This type of mixed components, to our knowledge, is the first case to be reported.