Inflammatory pituitary gland changes in cases of Rathke's cleft cyst associated with panhypopituitarism

Object: Pituitary dysfunction associated with Rathke cleft cyst is not necessarily related to the size of the lesion. We hypothesized that any other factors could affect decreased pituitary function in cases with Rathke cleft cyst. Methods and Results: We studied 27 cases of Rathke cleft cyst we surgically treated between 1983 and 2002. The diameter of Rathke cleft cyst, which was calculated from MR images, was not significantly correlated to pituitary dysfunction. HE section of 6 surgical cases with panhypopituitarism demonstrated remarkable destruction of the acinar structures of the anterior pituitary lobe adjacent to each Rathke cleft cyst, which included lymphocyte and macrophage infiltration, decreased collagen tissue and calcification. In contrast, HE findings of 4 surgical cases and 4 autopsy cases with normal pituitary function showed that intact acinar structures surrounded Rathke cleft cyst. Conclusion: There is the possibility that pituitary dysfunction in cases of Rathke cleft cyst is caused by an inflammatory reaction, which may be induced by cyst contents leaking into the surrounding pituitary tissue.