Pathophysiology
In terms of the mechanism of congenital hyperinsulinism one sees that channel trafficking requires KATP channels need the shielding of ER retention signal.E282K prevents the KATP channel surface expression, the C-terminus (SUR1 subunit) is needed in KATP channel mechanism.R1215Q mutations (ABCC8 gene) affect ADP gating which in turn inhibits KATP channel. Diagnostic
In terms of the investigation of congenital hyperinsulinism, valuable diagnostic information is obtained from a blood sample drawn during hypoglycemia,  detectable amounts of insulin during hypoglycemia are abnormal and indicate that hyperinsulinism is likely to be the cause. Inappropriately low levels of free fatty acids and ketones provide additional evidence of insulin excess. An additional piece of evidence indicating hyperinsulinism is a usually high requirement for intravenous glucose to maintain adequate glucose levels, the minimum glucose required to maintain a plasma glucose above 70 mg/dl. A GIR above 8 mg/kg/minute in infancy suggests hyperinsulinism. A third form of evidence suggesting hyperinsulinism is a rise of the glucose level after injection of glucagon at the time of the low glucose.Diagnostic efforts then shift to determining the type- elevated ammonia levels or abnormal organic acids can indicate specific, rare types. Intrauterine growth retardation and other perinatal problems raise the possibility of transience, while large birthweight suggests one of the more persistent conditions. Genetic screening is now available within a useful time frame for some of the specific conditions. It is worthwhile to identify the minority of severe cases with focal forms of hyperinsulinism because these can be completely cured by partial pancreatectomy.
Fetus in fetu differs from fetiform teratoma in having an apparent spine and bilateral symmetry.Most authorities agree that fetiform teratomas are highly developed mature teratomas;  the natural history of fetus in fetu is controversial. There also may be a cultural difference, with fetiform teratoma being reported more often in ovarian teratomas (by gynecologists) and fetus in fetu being reported more often in retroperitoneal teratomas (by general surgeons). Fetus in fetu has often been interpreted as a fetus growing within its twin. As such, this interpretation assumes a special complication of twinning, one of several grouped under the term parasitic twin. In this regard, in many cases the fetus in fetu is reported to occupy a fluid-filled cyst within a mature teratoma. Cysts within mature teratoma may have partially developed organ systems; reports include cases of partial cranial bones, long bones and a rudimentary beating heart.Regardless of whether fetus in fetu and fetiform teratoma are one entity or two, they are distinct from and not to be confused with ectopic pregnancy. Struma ovarii
A struma ovarii (also known as goitre of the ovary or ovarian goiter) is a rare form of mature teratoma that contains mostly thyroid tissue. Epignathus
Epignathus is a rare teratoma originating in the oropharyngeal area that occurs in utero. It presents with a mass protruding from the mouth at birth. Untreated, breathing is impossible. An EXIT procedure is the recommended initial treatment. Signs and symptoms
Teratomas may be found in babies, children, and adults.