Neurilemoma-like uterine myomas: an ultrastructural reaffirmation of their non-Schwannian nature.

Some uterine leiomyomas demonstrate a curious rhythmic pattern of cellular arrangement, suggesting the appearance of nerve sheath tumors. Leiomyomas of similar appearance are more frequently found in the gastrointestinal tract. Ultrastructural examination of two such tumors from the uterus, one simulating the Antoni type A pattern and the other predominantly of the Antoni type B pattern, showed features of smooth muscle cells to be present in both. There also was a close fine structural resemblance to light microscopically similar tumors of the gastrointestinal tract. This study should dispel the implications that these tumors are of Schwannian origin.