POMC and primary pigmented nodular adrenocortical disease: Patients with PPNAD presented with an ACTH-independent form of CS, characterized by decreased or undetectable ACTH levels, elevated serum cortisol concentrations with loss of circadian rhythm, and paradoxical increase in UFC excretion after HDDST (Liddle test), with a maximum specificity of 100% (6, 39, 73, 74).