Letter: Dermatitis herpetiformis, iodine compounds and thyrotoxicosis

Prevalence of thyroid abnormalities in patients with dermatitis herpetiformis and in control subjects with HLA-B8/-DR3

PURPOSE

The prevalence of thyroid dysfunction as measured by the presence of overt thyroid disease, abnormal results of thyroid function tests, or antithyroid antibodies was compared in patients with dermatitis herpetiformis (DH) and a normal control group who had the HLA-B8/-DR3 haplotype.

PATIENTS AND METHODS

The study population consisted of 56 patients with DH and 26 control subjects with the HLA-B8/-DR3 haplotype. All were examined for thyroid function abnormalities and thyroid autoantibodies.

RESULTS

Patients with DH had a statistically significant increase in the prevalence of abnormal thyroid function test results and autoantibodies: 32% versus 4% for controls (Z = 2.01, p less than 0.02). In patients with DH, hypothyroidism was the most common thyroid abnormality (12 of 56) followed by hyperthyroidism (four of 56). Two patients had normal thyroid function test results with thyroid autoantibodies. Risk factors for thyroid abnormalities in patients with DH were increasing age (chi 2 = 6.55, p less than 0.02, significant) and the presence of thyroid microsomal antibodies. The HLA-B8/-DR3 haplotype was not a risk factor for thyroid abnormalities.

CONCLUSION

The findings suggest that thyroid disease is independently associated with DH. Examination of patients with DH should include thyroid function tests along with assays for antithyroid antibodies.

The prevalence of thyroid autoantibodies in dermatitis herpetiformis

The prevalence of IgG class thyroglobulin and microsomal antibodies, estimated using a sensitive ELISA, was 48% in 115 patients with dermatitis herpetiformis, which was significantly greater than the prevalence of 16% in 107 unselected controls without dermatitis herpetiformis. IgA class thyroid antibodies were found in 29% of dermatitis herpetiformis patients. Overt thyroid disease had been diagnosed in six (5%) of the dermatitis herpetiformis group and a further six patients had elevated TSH levels. The presence of thyroid antibodies was not associated with particular HLA-DR antigens. These results demonstrate the frequent occurrence of thyroid antibodies in dermatitis herpetiformis, although thyroid failure is less commonly associated with this condition. Immune response genes outside the HLA-DR region may be involved in the immune hyper-responsiveness seen in dermatitis herpetiformis which is reflected in the high prevalence of thyroid autoimmunity.

Dermatitis herpetiformis: effects of sulfones and sulfonamides on neutrophil myeloperoxidase-mediated iodination and cytotoxicity

The effects of sulfones and sulfonamides on neutrophil myeloperoxidase-mediated iodination and cytotoxicity were studied using in vitro assays to measure these parameters. Leukocyte iodination was documented using a quantitative assay to measure the iodination of protein by human neutrophils undergoing phagocytosis. Cytotoxicity for the tumor cell line LSTRA by human neutrophils activated by exposure to phorbol myristate acetate was measured by a 51Cr release assay. Dapsone, diasone, and sulfapyridine, at concentrations comparable to serum levels obtained by therapeutic doses of drug, effectively inhibited iodination and cytotoxicity mediated by human neutrophils. Other sulfonamides showed little inhibition of either iodination or cytotoxicity. The amount of inhibition was comparable to that seen with the inhibitors azide or cyanide and occurred in a dose dependent manner with all three drugs. A cell-free cytotoxic system using myeloperoxidase, iodide, a H2O2 generating system, and target cells also showed inhibition by dapsone, diasone and sulfapyridine in a similar fashion. The active drugs inhibited both the intra- and the extracellular myeloperoxidase-H2O2-halide cytotoxic systems. Serial iodination studies of four dermatitis herpetiformis patients, evaluated while taking dapsone or sulfapyridine, showed inhibition of iodination by either drug. Levels of IgA immune complexes, as measured by the Raji cell radioimmune assay adapted for IgA, did not change when medication was withheld. These studies demonstrate that dapsone, diasone, and sulfapyridine inhibit both neutrophil iodination and cytotoxicity for tumor cells, while other sulfonamides have no effect. This confirms previous studies showing inhibition by myeloperoxidase mediated iodination by dapsone. Furthermore, the effect on neutrophils is quickly reversible; in vivo administered drug has no effect on in vitro function. The active drugs inhibit both intra- and extracellular cytotoxic systems. This may represent an important mechanism by which these drugs produce their therapeutic effects when used to treat inflammatory skin diseases.

Treatment of dermatitis herpetiformis with cholestyramine

Two patients with clinically and histologically typical dermatitis herpetiformis showed a dramatic clearing of their skin lesions in association with an oral dose of 4 g of cholestyramine three times a day. Reappearance of the lesions occurred on the discontinuance of the therapy, followed by remission on resumption of cholestyramine. It is postulated that the non-absorbable anion exchange resin, cholestyramine, may have bound and hence blocked absorption of an unidentified compound (possibly gluten, iodine, or endotoxin) critical to the pathogenesis of dermatitis herpetiformis.

Internal disorders associated with bullous disease of the skin. A critical review

Acquired bullous dermatoses, including pemphigus, bullous pemphigoid (BP), dermatitis herpetiformis (DH), and porphyria cutanea tarda (PCT), have been reported in association with multiple internal disorders. These associations, as well as those cases of bullous lesions in specific systemic disorders, may prove to be important markers of internal disease. Patients with acquired bullous disorders may require specialized evaluation or follow-up. Pemphigus is associated with thymoma and/or myasthenia gravis; however, the course of disease is rarely affected. Pemphigus, pemphigoid, and DH are associated with other autoimmune disorders. Particularly important are the associations of pemphigoid and rheumatoid arthritis (RA) and DH and thyroid disorders. PCT may occur with cutaneous lupus erythematosus (LE). Malignancy is rarely associated with bullous dermatoses except coincidentally, with the exception of porphyria and hepatic tumors, and DH and lymphoma of the gastrointestinal tract.

Dermatitis herpetiformis and thyrotoxicosis

Dermatitis herpetiformis has been associated with a variety of thyroid abnormalties. A case of thyrotoxicosis in a patient with pre-existing dermatitis herpetiformis is reported. Thyroid antibodies were present in the serum. This may suggest an immunologic relationship between dermatitis herpetiformis and thyroid disorders, that may be more than fortuitous.