<prompt> In which of the following conditions acquired secondary megacolon seen?Fissure in-anoComplete absence of parasympathetic ganglion cellsAbsence of sympathetic ganglion cellsRectal malignancy  <response>: Acquired megacolon - marked dilatation of the entire colon or its segment due to acquired causesrectum and sigmoid colon are dilated. Normal ganglions are present in all levels. It is seen in children with faulty toilet training resulting in chronic bowel dilatation. Causes include: Obstructive- tumours rectal malignancy, post inflammatory strictures Endocrine- myxoedema, cretinism CNS disorders- spina bifida, paraplegia, parkinsonism Psychogenic- emotional disturbances, psychiatric disorders Chagas disease dt infection with Trypanosoma cruzi- acquired loss of ganglion cells Congenital absence of ganglion cells in the bowel wall results in congenital megacolonHirschsprungs disease. Fissure in ano causes anal sphincter spasm, but does not result in megacolon. Reference : page 580 Textbook of pathology Harshmohan 6th edition 