Lymphoma in patients with dermatitis herpetiformis and their first-degree relatives

Background The risk for lymphoma is increased in both dermatitis herpetiformis (DH) and in coeliac disease. The lymphoma most associated with coeliac disease is enteropathy-associated T-cell lymphoma. Objectives To study the occurrence and type of lymphoma in a large series of patients with DH and their first-degree relatives. Methods The occurrence of lymphoma was studied in 1104 patients consecutively diagnosed with DH in two university hospitals during 1969-2001. A questionnaire was sent to 341 patients to examine the occurrence of lymphoma in their 1825 first-degree relatives. To analyse whether the DH patients with lymphoma had adhered to a gluten-free diet similarly to the patients without lymphoma, two age- and sex-matched patients with DH served as controls for each index case. Data on the gluten-free diet were collected from prospectively completed dietary forms and also from medical records. Results Eleven (1%) patients contracted lymphoma 2-31 years after the diagnosis of DH. Eight had B-cell-type lymphoma, two enteropathy-associated T-cell lymphoma and one remained unclassified due to missing material. Three (0.2%) of the first-degree relatives contracted lymphoma, all B-cell type. The I I DH patients with lymphoma had adhered to a gluten-free diet significantly less strictly than the DH controls without lymphoma. Conclusions The present study documents that patients with DH can have both B- and T-cell lymphoma. The DH patients with lymphoma had not adhered as strictly to the gluten-free diet as the control patients without lymphoma. The occurrence of lymphoma in the first-degree relatives was lower than in the patients with DH.