The MACS group compared to the NFAI one was significantly older at diagnosis (67.2 ± 8.7 years vs. 64.0 ± 9.8 years; p = 0.009) and showed lower basal ACTH levels (14.1 ± 9.9 ng/L vs. 18.6 ± 11.2 ng/L; p = 0.003), a higher mean diameter of the largest adrenal nodule at CT (22.7 ± 7.3 mm vs. 18.1 ± 6.1 mm; p < 0.001), and a higher percentage of patients affected by osteoporosis 16% vs. 6%; p = 0.015). The gene discussed is POMC; the disease is osteoporosis.