Red herring: Undervirilisation of male foetus due to maternal oestrogen-producing tumour or an intrinsic problem?

Disorders of sexual differentiation (DSD) are a cause for significant anxiety. A structured and rapid investigation strategy gives the family solace and the opportunity to institute appropriate therapy. We describe a 46XY undervirilised DSD that was attributed to an estrogen-secreting maternal ovarian cystadenoma tumour. However, diligent and complete workup revealed a different diagnosis altogether. Conservative therapy to support this preterm neonate was first followed; confirmation of the diagnosis helped institute an endocrine consult, anticipatory guidance and regular follow up. Initially apparent causes of DSD must not hamper a detailed algorithmic approach toward a definitive diagnosis.