Unilateral jugular stenosis is easily mistaken as jugular hypoplasia for their similar jugular appearances. This study aimed to propose a scheme to differentiate acquired internal jugular vein stenosis (IJVS) from congenital jugular variation through two case examples.We presented a dynamic evolution process of the IJVS formation, through a case of a 17-year-old female with paroxysmal nocturnal hemoglobinuria (PNH)-associated right internal jugular venous thrombosis (IJVT), which resulted in post-thrombotic IJVS in the rare context of rapid recanalization. Meanwhile, we compared her images with images of a 39-year-old healthy male with hypoplastic IJV to determine the differences between the acquired IJVS and congenital dysplasia.Based on the first case, we noticed the whole formative process of acquired IJVS from nothing to something. Meantime, we found that acquired IJVS was surrounded by abnormal corkscrew collaterals as imaged on contrast-enhanced magnetic resonance venography (CE-MRV), and the ipsilateral jugular foramen (JF) was normal-sized as displayed on computer tomography (CT). Conversely, jugular hypoplasia was with ipsilateral stenotic JF and without serpentine collaterals.JF morphology and venous collaterals may be deemed as surrogate identifiers to distinguish acquired unilateral IJVS from jugular hypoplasia.© 2022. The Author(s).