BACKGROUND: No significant differences in gross and light- microscopic features have been reported between preclinical and overt Cushing's adenomas. In this study, the ultrastructural differences between the two syndromes was attempted to be clarified. METHODS: Two preclinical Cushing's syndrome adenomas and two overt Cushing's syndrome adenomas obtained from surgical extirpation were examined in an electron microscopic study. RESULTS: Light microscopically, the adenomas of both syndromes were composed predominantly of clear cells, with few compact cells. Ultrastructurally, the prominent differences were of development in each organelle: the preclinical Cushing's adenomas had undeveloped mitochondria, which were smaller in size and had sparse cristae, lysosomes and polysomes, whereas the overt Cushing's adenomas contained well-developed mitochondria which were larger in size and were filled with abundant cristae, smooth endoplasmic reticulum (SER), lysosomes and polysomes. CONCLUSIONS: Preclinical Cushing's syndrome adenomas were ultrastructurally characterized by a reduced number of cellular organelles such as mitochondria and SER, which are necessary to synthesize glucocorticoid hormones. However, examination of a greater number of adenomas will be required to be able to draw conclusions on the ultrastructural differences between the two syndromes.
BACKGROUND: No significant differences in gross and light- microscopic features have been reported between preclinical and overt Cushing's adenomas. In this study, the ultrastructural differences between the two syndromes was attempted to be clarified. METHODS: Two preclinical Cushing's syndrome adenomas and two overt Cushing's syndrome adenomas obtained from surgical extirpation were examined in an electron microscopic study. RESULTS: Light microscopically, the adenomas of both syndromes were composed predominantly of clear cells, with few compact cells. Ultrastructurally, the prominent differences were of development in each organelle: the preclinical Cushing's adenomas had undeveloped mitochondria, which were smaller in size and had sparse cristae, lysosomes and polysomes, whereas the overt Cushing's adenomas contained well-developed mitochondria which were larger in size and were filled with abundant cristae, smooth endoplasmic reticulum (SER), lysosomes and polysomes. CONCLUSIONS: Preclinical Cushing's syndrome adenomas were ultrastructurally characterized by a reduced number of cellular organelles such as mitochondria and SER, which are necessary to synthesize glucocorticoid hormones. However, examination of a greater number of adenomas will be required to be able to draw conclusions on the ultrastructural differences between the two syndromes.