SummaryUnilateral Nevoid Telangiectasia Syndrome (UNTS) is a rare vascular dermatosis characterized by linearly arranged telangiectasias in a unilateral, dermatomal, or blaschkoid pattern that can be congenital or acquired. We report on a 36-year-old Caucasian female who presented UNTS localized in the supraclavicular dermatomal region. The lesions were present since puberty, but suddenly worsened during pregnancy, and completely resolved after delivery. Histological examination revealed ectatic blood vessels in the dermis. Immunochemistry showed the expression of estrogen receptors limited to perivascular cells of ectatic vessels but not on endothelial cells. UNTS associated with pregnancy may be due to excessive estrogenic stimulation of pericytes, which in turn allow vasodilatation. This may also explain the spontaneous resolution of the lesions following delivery.