<prompt> Rhinolith can cause perforation of nasal septum by-Pressure necrosisMalignant transformationAutoimmune reactionHypersensitivity reaction  <response>: Ans. is a i.e., Pressure necrosis A rhinolith usually forms around the nucleus of a small exogenous foreign body, blood clot or inspissated secretions by slow deposition of calcium and magnesium salts. Over a period of time, it grows into a large, irregular mass, which fills the nasal cavity and then may cause pressure necrosis of the septum andor lateral wall of nose. 