Hypertension, hypokalemia, and left adrenal tumor mimicking primary aldosteronism in a patient with 17α-hydroxylase deficiency

17 α -hydroxylase deficiency (17OHD) is a rare disorder of secondary hypertension caused by congenital adrenal hyperplasia. In addition, co-occurrence of an adrenal tumor with 17OHD is extremely rare and easily misdiagnosed. A 33-year-old female with sicca syndrome, persistent hypertension, hypokalemia, and a left adrenal tumor was referred for confirmation of primary aldosteronism. However, the absence of secondary sexual characteristics, persistent growth beyond puberty, and laboratory data of low plasma renin activity, high aldosterone, low cortisol, low sex hormones, elevated adrenocorticotropic hormone, elevated luteinizing hormone, elevated follicle-stimulating hormone, and most importantly, decreased 17-hydroxypregnenolone, supported a diagnosis of 17OHD. We sequenced the CYP17A1 gene of the patient and her parents, which demonstrated genetic defects (D487-S,488-F489 deletion and Y329K418X). 17OHD was diagnosed. The left adrenal tumor was assessed, and a non-functional adrenal incidentaloma was confirmed; NP-59 adrenal cortical scintigraphy and adrenal venous sampling showed no functional activity and non-lateralization. Hormone replacements with estrogen, spironolactone, and prednisolone were given. The patient became more feminized and confident, and her hypertension was controlled. Early diagnosis and treatment of 17OHD not only can prevent delay development of secondary sexual characteristics but also help the patient maintain mental health and improve their quality of life. In addition, the concomitant presence of a left adrenal tumor makes misdiagnosis of a functional adenoma more likely, possibly causing unnecessary surgery and delay inappropriate treatment.