The adrenal cortex in ectopic adrenocorticotropic hormone syndrome: A morphological study with histology, transmission and scanning electron microscopy, flow cytometry, and image analysis.

The surgically removed adrenal glands of an 83-year-old woman with ectopic adrenocorticotropic hormone syndrome were studied by light microscopy, transmission and scanning electron microscopy, and flow-cytometric and image analyses for DNA ploidy. Light microscopy revealed marked adrenocortical hyperplasia. The majority of the large fasciculata cells were lipid-depleted compact cells, some with large nuclei. By transmission electron microscopy, marked abundance of smooth endoplasmic reticulum was noted. Mitochondria were large, had vesicular or tubulovesicular cristae, and showed focal cavitation in their internal compartments. Lysosomes were numerous in many large cells. Long microvilli were prominent on the cell surfaces and interdigitating with adjacent cells. Scanning electron microscopy disclosed many conspicuous microvilli and small pits on the cell membranes. The microvillous hyperplasia is most likely destined to facilitate uptake of hormone precursors or discharge of synthesized hormones by increasing the cell surface area; the small pits on cell membranes may reflect endocytosis of hormone precursors required for accelerated corticosteroid synthesis. Flow-cytometric and image analysis of the adrenocortical cells showed aneuploid and polyploid DNA populations, providing evidence that aneuploidy and polyploidy may occur not only in neoplastic but also in hyperplastic cells.