In 2 women with known
Addison's disease, progressive
hyperpigmentation reappeared years after an initial remission under conventional substitution
therapy with
cortisone. Excessively elevated plasma
ACTH concentrations and radiological evidence of sella turcica deformation led to the diagnosis of
ACTH-producing
adenomas and prompted their removal by transsphenoidal microsurgery. In one patient, a large Crooke's cell
adenoma with extensive extrasellar expansion had caused severe and irreversible bilateral defects of the visual fields and unilateral
optic atrophy. Surgical removal of the tumour and
radiotherapy brought about a permanent disappearance of the
hyperpigmentation, but eventually led to
secondary hypothyroidism. In the second patients, the selective removal of a small intrasellar
eosinophilic adenoma consisting of
ACTH-producing cells did not alleviate the
hyperpigmentation and did not lower the plasma
ACTH concentration. However,
hyperpigmentation regressed markedly within a year of treatment with a higher dose of
cortisone. The rarity of similar cases in the literature seems to indicate that insufficient feedback suppression of
ACTH-producing cells in treated
Addison's disease does not by itself induce the development of a
pituitary adenoma, but might promote the growth of an independently and coincidentally occurring microadenoma, which would have caused
Cushing's disease in a person with intact adrenal glands.