What is the diagnostic evaluation for a patient with suspected celiac disease (CD) presenting with oral ulcers and an elbow rash, possibly dermatitis herpetiformis (DH)?

From the Guidelines

The diagnostic evaluation for a patient with suspected celiac disease presenting with oral ulcers and possible dermatitis herpetiformis should begin with serologic testing while the patient remains on a gluten-containing diet, as recommended by the most recent guidelines 1. The initial blood tests should include tissue transglutaminase antibodies (tTG-IgA) and total IgA levels.

• If the patient is IgA deficient, deamidated gliadin peptide antibodies (DGP-IgG) or tTG-IgG should be ordered.
• For the suspected dermatitis herpetiformis, a skin biopsy from perilesional skin (not from the blister itself) should be performed for direct immunofluorescence to detect granular IgA deposits in the dermal papillae.
• Confirmation of celiac disease requires an upper endoscopy with multiple duodenal biopsies (at least four from the second part of the duodenum and two from the duodenal bulb) while the patient is still consuming gluten, as supported by the guidelines from the British Society of Gastroenterology 1.
• For patients with dermatitis herpetiformis, the skin biopsy may be sufficient for diagnosis without intestinal biopsy.
• HLA-DQ2 and DQ8 testing can be helpful in certain cases, particularly to rule out celiac disease if negative, as stated in the guidelines 1. These diagnostic steps are essential because both conditions respond to strict gluten elimination, and proper diagnosis guides long-term management and monitoring for complications, ultimately improving morbidity, mortality, and quality of life. The most recent and highest quality study 1 provides the best evidence for these recommendations, and its findings should be prioritized in clinical practice.

From the Research

Diagnostic Evaluation for Suspected Celiac Disease with Oral Ulcers and Elbow Rash

The diagnostic evaluation for a patient with suspected celiac disease (CD) presenting with oral ulcers and an elbow rash, possibly dermatitis herpetiformis (DH), involves several steps:

• Clinical presentation: The patient's symptoms, such as oral ulcers and elbow rash, should be evaluated in the context of CD and DH 2, 3.
• Serologic tests: Serum antibodies against tissue transglutaminase (tTG) can be used in the serologic screening and follow-up of dietary compliance of patients with CD 3, 4, 5, 6.
• Intestinal biopsy: Traditionally, small intestinal biopsy has been considered the gold standard for the diagnosis of CD 4, 5.
• Dermatitis herpetiformis diagnosis: DH diagnosis is confirmed by showing granular immunoglobulin A deposits in the papillary dermis 2.

Diagnostic Tests

The following diagnostic tests can be used to evaluate a patient with suspected CD and DH:

• Anti-tissue-transglutaminase antibodies (tTGA): High titres of tTGA can reduce the need for intestinal biopsy for diagnosis of CD 5.
• Anti-endomysial antibodies: These antibodies can be used to detect gluten sensitivity in patients with DH 6.
• Anti-gliadin antibodies: These antibodies can be used to detect gluten sensitivity in patients with DH, but their performance may vary depending on the degree of enteropathy 6.
• Deamidated synthetic gliadin-derived peptides (a-GDP): The detection of a-GDP antibodies was found to be the most reliable tool to identify gluten sensitivity in DH patients presenting a wide range of intestinal damage 6.

Treatment and Management

The treatment of choice for patients with DH is a gluten-free diet (GFD) in which uncontaminated oats are allowed 2, 3.

• Additional treatment with dapsone may be necessary to rapidly control the rash and itching in patients with DH 2, 3.
• A strict lifelong GFD alone is required after the initial treatment with dapsone 2.