Diagnosis and Management of Adult Celiac Disease
Diagnosis and Management of Adult Celiac Disease
While the current standard tests of serology and conventional histology are usually adequate to reach a diagnosis of CD, there are patients whose tests are equivocal and diagnostic uncertainty remains. Several novel diagnostic approaches have been undertaken. The deposition of IgA antibodies in close proximity to TG2 in the small intestine has shown promise as a way of defining early or potential CD in patients who are seropositive but lack any of the usual histological markers for CD. Recent work from Finland on IgA-TG2 autoantibody deposition in the small intestine in such patients shows promise in delivery of an early prediction of development of CD. However, this is currently experimental and the methodology requires tissue sections frozen in liquid nitrogen. Another diagnostic method meriting further evaluation is EmA assay in the culture medium of small intestinal biopsies. Other investigators have reported their findings using new techniques associated with endoscopy to enhance the diagnosis of CD. These include confocal microscopy, high-resolution magnification endoscopy, optical band imaging and optimal coherence tomography. These novel techniques are still limited by availability, tolerability and cost. However, the immersion technique and dye enhancement in which the endoscopist instills water or a contrast dye (for example, indigo carmine or methylene blue) into the bowel lumen, with or without the assistance of magnification endoscopy, enhancing the visualisation of the villus can be readily used and improves visualisation of villi, thus increasing the sensitivity for detection of villous atrophy.
Dermatitis herpetiformis (DH) is the cutaneous manifestation of gluten-sensitive enteropathy precipitated by exposure to dietary gluten. It is characterised clinically by herpetiform clusters of intensely itchy urticated papules and small blisters distributed on the extensor aspects of the elbows and knees and over the buttocks and on the scalp. The commonest age of onset is between the third and fourth decade, though the condition may occur at any age after weaning. Male patients are affected twice as often as female patients. For the majority of patients the disease is lifelong with varying periods of activity, potentially due to varying degrees of dietary adherence.
The major diagnostic criterion for diagnosis is the presence of granular IgA deposits in the dermal papillae of uninvolved perilesional skin as shown by direct immunofluorescence, and the diagnosis should not be made unless this has been confirmed.
Less than 10% of patients with DH have symptoms or signs of malabsorption but most have evidence of CD that responds to a GFD and relapses on gluten challenge. Patients with DH present with their skin manifestations and are not usually troubled by the underlying small bowel problem at the time of presentation. Abnormality of the small intestinal mucosa with either total or subtotal villous atrophy is found in approximately 70% of patients with DH. A further 25% have normal villous architecture with increased IELs.
DH shares with CD an increased risk of developing lymphomas but this seems to be confined to those with severe gut involvement. The risk similarly declines with time on a strict GFD.
Due to rash and itch, dapsone is often initiated. More than 70% of patients on a strict GFD are however able to slowly wean off dapsone over a period of 24 months.
Novel Diagnostic Methods
While the current standard tests of serology and conventional histology are usually adequate to reach a diagnosis of CD, there are patients whose tests are equivocal and diagnostic uncertainty remains. Several novel diagnostic approaches have been undertaken. The deposition of IgA antibodies in close proximity to TG2 in the small intestine has shown promise as a way of defining early or potential CD in patients who are seropositive but lack any of the usual histological markers for CD. Recent work from Finland on IgA-TG2 autoantibody deposition in the small intestine in such patients shows promise in delivery of an early prediction of development of CD. However, this is currently experimental and the methodology requires tissue sections frozen in liquid nitrogen. Another diagnostic method meriting further evaluation is EmA assay in the culture medium of small intestinal biopsies. Other investigators have reported their findings using new techniques associated with endoscopy to enhance the diagnosis of CD. These include confocal microscopy, high-resolution magnification endoscopy, optical band imaging and optimal coherence tomography. These novel techniques are still limited by availability, tolerability and cost. However, the immersion technique and dye enhancement in which the endoscopist instills water or a contrast dye (for example, indigo carmine or methylene blue) into the bowel lumen, with or without the assistance of magnification endoscopy, enhancing the visualisation of the villus can be readily used and improves visualisation of villi, thus increasing the sensitivity for detection of villous atrophy.
Dermatitis Herpetiformis
Dermatitis herpetiformis (DH) is the cutaneous manifestation of gluten-sensitive enteropathy precipitated by exposure to dietary gluten. It is characterised clinically by herpetiform clusters of intensely itchy urticated papules and small blisters distributed on the extensor aspects of the elbows and knees and over the buttocks and on the scalp. The commonest age of onset is between the third and fourth decade, though the condition may occur at any age after weaning. Male patients are affected twice as often as female patients. For the majority of patients the disease is lifelong with varying periods of activity, potentially due to varying degrees of dietary adherence.
The major diagnostic criterion for diagnosis is the presence of granular IgA deposits in the dermal papillae of uninvolved perilesional skin as shown by direct immunofluorescence, and the diagnosis should not be made unless this has been confirmed.
Less than 10% of patients with DH have symptoms or signs of malabsorption but most have evidence of CD that responds to a GFD and relapses on gluten challenge. Patients with DH present with their skin manifestations and are not usually troubled by the underlying small bowel problem at the time of presentation. Abnormality of the small intestinal mucosa with either total or subtotal villous atrophy is found in approximately 70% of patients with DH. A further 25% have normal villous architecture with increased IELs.
DH shares with CD an increased risk of developing lymphomas but this seems to be confined to those with severe gut involvement. The risk similarly declines with time on a strict GFD.
Due to rash and itch, dapsone is often initiated. More than 70% of patients on a strict GFD are however able to slowly wean off dapsone over a period of 24 months.
