Ultrastructure and steroid-binding studies in leiomyomatosis peritonealis disseminata.

Leiomyomatosis peritonealis disseminata (LPD) is characterized by the development of numerous leiomyomata throughout the peritoneal cavity which appear grossly malignant but histologically benign. The etiology of this disorder has been controversial. The tenth reported case of LPD is presented with ultrastructural evidence that these tumors arise from smooth muscle cells. The cytoplasmic estrogen and progesterone bindings by these tumors were ninefold and twofold greater than receptor concentrations in normal myometrium from the same patient. In addition to the steroid binding data, the strong association of this disorder with pregnancy or, as in this case, oral contraceptives suggests that the stimulus for neoplastic initiation and growth is hormonally related.