Tram-line calcification on skull X-ray is characteristically seen in the following condition:

Sturge-Weber syndrome consists of a congenital, usually unilateral, cutaneous capillary angioma involving the upper face, leptomeningeal angiomatosis and choroidal angioma. There may be contralateral homonymous hemianopia, hemiparesis and hemisensory disturbance, ipsilateral glaucoma, seizures and mental subnormality. Skull radiographs taken after the first 2 years of life usually reveal gyriform ("tramline") intracranial calcification, especially in the parieto-occipital region, due to mineral deposition in the coex beneath the intracranial angioma. Ref: Aminoff M.J., Kerchner G.A. (2013). Chapter 24. Nervous System Disorders. In M.A. Papadakis, S.J. McPhee, M.W. Rabow, T.G. Berger (Eds), CURRENT Medical Diagnosis & Treatment 2014.