Focal cortical dysplasia (FCD) is a congenital abnormality of brain development where the neurons in an area of the brain failed to migrate in the proper formation in utero. Focal means that it is limited to a focal zone in any lobe. Focal cortical dysplasia is a common cause of intractable epilepsy in children and is a frequent cause of epilepsy in adults. There are three types of FCD with subtypes, including type 1a, 1b, 1c, 2a, 2b, 3a, 3b, 3c, and 3d, each with distinct histopathological features. All forms of focal cortical dysplasia lead to disorganization of the normal structure of the cerebral cortex :

Type 1 FCD exhibits subtle alterations in cortical lamination. Type 2a FCD exhibits neurons that are larger than normal that are called dysmorphic neurons (DN). FCD type 2b exhibits complete loss of laminar structure, and the presence of DN and enlarged cells are called balloon cells (BC) for their large elliptical cell body shape, laterally displaced nucleus, and lack of dendrites or axons. The developmental origin of balloon cells is currently believed to be derived from neuronal or glial progenitor cells. Balloon cells are similar in structure to giant cells in the disorder tuberous sclerosis complex. Type 3 FCDs are cortical disorganisation associated with other lesions such as hippocampal sclerosis (type 3a), long-term epilepsy-associated tumors (3b), vascular malformations (3c) or scar/hypoxic damages (3d).Recent studies have demonstrated that FCD types 2a and 2b result from somatic mutations in genes that encode components of the mammalian target of rapamycin (mTOR) pathway.
Ectopic ureter (or ureteral ectopia) is a medical condition where the ureter, rather than terminating at the urinary bladder, terminates at a different site. In males this site is usually the urethra, in females this is usually the urethra or vagina. It can be associated with renal dysplasia, frequent urinary tract infections, and urinary incontinence (usually continuous drip incontinence). Ectopic ureters are found in 1 of every 2000–4000 patients, and can be difficult to diagnose, but are most often seen on CT scans.Ectopic ureter is commonly a result of a duplicated renal collecting system, a duplex kidney with 2 ureters. In this case, usually one ureter drains correctly to the bladder, with the duplicated ureter presenting as ectopic.The embryology that explains the pathology of an ectopic ureter is a cephalad origin of the ureteral bud on the mesonephric duct. With an abnormally long common excretory duct, the ureter never becomes incorporated into the bladder, and, therefore, remains ectopic. In the female, the most common locations of an ectopic ureter are the bladder neck, urethra, or Gartners duct which lies between the urethra and the anterior vaginal wall. See also
Ectopia (disambiguation)

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