Thistle-tube appearance is a characteristic feature of:

Radiographic features of type II (coronal) dentin dysplasia: The permanent teeth exhibit an abnormally large pulp chamber in the coronal portion of the tooth, often described as ‘thistle-tube’ in shape, and within such areas radiopaque foci resembling pulp stones may be found. Ref: Shafer's textbook of oral pathology 7th edition page 57