Abstract
A diagnosis of congenital adrenal hyperplasia (CAH) in a '46, XX' newborn with ambiguous genitalia is like a 'knee jerk reaction' of the paediatrician because of its higher frequency and life-threatening consequences if remain undiagnosed and hence untreated. Aromatase deficiency (AD), a rare cause of '46, XX' disorder of sex development, mimics virilising CAH in many aspects; thus, the disease is often overlooked. Diagnosis of AD in women is much easier around puberty due to the presence of primary amenorrhoea, undeveloped breasts, androgen excess and tall stature with eunuchoid proportions. Diagnosing AD with confidence immediately after birth or during early childhood is a challenging task without genetic analysis. In resource-restricted settings, AD remains a diagnosis of exclusion particularly in this age group and history of maternal virilisation, non-progressive genital ambiguity, elevated gonadotrophins (follicle-stimulating hormone >>luteinising hormone), mildly delayed bone age with/without enlarged polycystic ovaries serve as important clues to the underlying AD.