Duodenal lymphocytosis, sometimes called lymphocytic duodenitis, lymphocytic duodenosis, or duodenal intraepithelial lymphocytosis, is a condition where an increased number of intra-epithelial lymphocytes is seen in biopsies of the duodenal mucosa when these are examined microscopically. This form of lymphocytosis is often a feature of coeliac disease but may be found in other disorders. Presentation
The condition is characterised by an increased proportion of lymphocytes in the epithelium of the duodenum, usually when this is greater than 20-25 per 100 enterocytes. Intra-epithelial lymphocyte (IEL) are normally present in intestine and numbers are normally greater in the crypts and in the jejunum; these are distinct from those found in the lamina propria of the intestinal mucosa. IELs are mostly T cells. Increased numbers of IELs are reported in around 3% of in duodenal biopsies, depending on case mix, but may be increasingly being found, in up to 7%. Causes
The list of possible causes is wide, including coeliac disease, environmental enteropathy (tropical sprue), autoimmune enteropathy, small intestinal bacterial overgrowth, NSAID damage, Helicobacter pylori, other infections and Crohns disease. Diagnosis
Diagnosis is made by accurate counting of intraepithelial lymphocytes during histological examination of the duodenum. The definition of the condition includes the requirement that the duodenal histological appearances are otherwise unremarkable, specifically with normal villous architecture.In coeliac disease (also known as gluten-sensitive enteropathy), duodenal lymphocytosis is found in untreated or partially treated cases. This is the least severe type of change, known as the Marsh I stage, in the classification of histological changes in coeliac disease.
People with 17q12 microdeletions who have normal fertility have a 50% chance of passing the deletion down to their offspring. Environmental factors have not been implicated in the syndrome. Diagnosis
Like other chromosomal microdeletions, 17q12 microdeletion syndrome is diagnosed via fluorescence in situ hybridization. Traditional karyotyping, used to diagnose major chromosomal disorders such as aneuploidy, is rarely sensitive enough to detect microdeletions. Treatment
As the underlying 17q12 microdeletion is an innate genetic disorder, it cannot by itself be treated. Rather, treatment is symptomatic and supportive. The high prevalence of kidney disease indicates routine monitoring of renal function, particularly in people taking potentially nephrotoxic medications such as lithium. The comorbities involved in 17q12 microdeletion syndrome require caution in medical treatment; for instance, the increased risk of diabetes requires strict monitoring for post-transplantation diabetes mellitus in kidney transplant patients, as does the risk of weight gain and diabetes from neuroleptic drugs in those with a mental health diagnosis. Epidemiology
The prevalence of 17q12 microdeletion syndrome is unknown, and it is likely to be underdiagnosed. 17q12 microdeletions are estimated to occur in approximately 1 in 600 people on the autism spectrum and 1 in 1,600 with schizophrenia, but are far rarer in the general population. General prevalence is estimated to be between 1 in 14,000 and 1 in 62,500.In addition to the increased prevalence in autism and schizophrenia, some other clinical populations have increased prevalence of 17q12 microdeletion syndrome. The condition occurs in approximately 2% of those with congenital kidney abnormalities and 3-6% of women with Müllerian agenesis.