Pituitary granuloma and chronic inflammation of hypophysis: Clinical and immunohistochemical studies

Summary

We describe five patients with chronic inflammation of the hypophysis including three pituitary granulomas of unknown aetiology. In contrast to the previously reported cases, the involvement of neurohypophysis or hypothalamus was a distinct clinical feature in these patients. Impairment of anterior pituitary function was less prominent, while polyuria and polydipsia occurred in all cases. Enlargement of the sella turcica was absent in three and slight in two cases. CT scan and MR images demonstrated a contrast-enhanced sellar mass in all patients; abnormally thickened pituitary stalk and infundibulum with contrast-enhancement was observed in four. The fibrous tissues were removed by the transsphenoidal approach in four patients, and by the subfrontal approach in one case. In all patients, the endocrinological dysfunction was prolonged. No increase in the size of the remaining pituitary mass was demonstrated on repeated MR images in any of the patients.

On histological examination, granulomatous formation was present in three samples, and multinucleated Langhans' giant cells were seen in one. The epithelioid cells and multinucleated giant cells constituting the granulomas were positive for anti-macrophage antibody. No firm laboratory or histological evidence was obtained supporting the presence of systemic disease leading to granulomas. In the other two cases, the pituitary lesions were composed of chronic inflammation tissue, and serum antipituitary antibodies were present in a patient with concurrent Hashimoto's thyroiditis.

Our experiences with chronic inflammation of the hypophysis indicate that these patients are best managed by histological confirmation of the lesion followed by adequate hormonal replacement.

Based on our findings and those reported in the literature, we propose that patients with granulomatous hypophysitis or chronic inflammation of the hypophysis be managed as follows: When an underlying disease is detected, the patient should begin to receive conservative treatment for the causative disease plus hormonal replacement therapy, as necessary. However, when visual disturbance is progressive and uncontrollable by conservative means, surgical decompression of the chiasma is required. If the pathogenesis of the pituitary lesion cannot be identified, surgical exploration is essential for a precise pathological diagnosis. When a granulomatous or chronic inflammatory process is evident intra-operatively, partial removal or biopsy are recommended. Radical resection of fibrous and adhesive tissue with infundibular impairment will lead not only to exacerbation of the pre-existing anterior- and/or posterior pituitary dysfunction, but also to grave hypothalamic injury.