Granuloma annulare: relationship to diabetes mellitus, thyroid disorders and tuberculin skin test

Background: Granuloma annulare is a benign inflammatory disease of the skin. The etiology and pathogenesis of the disease are not yet determined, but some authors have proposed that it might be associated with a variety of underlying conditions such as thyroid disorders, diabetes mellitus and positive tuberculin skin test. Objective: This study was conducted to find the probable relationship between granuloma annulare and diabetes mellitus, thyroid disorders and positive tuberculin skin test. Patients and methods: A total of 28 patients with granuloma annulare were recruited from our dermatology outpatient clinic, and data on sex, age and distribution of granuloma annulare lesions were collected. Forty-one age-and sex-matched apparently healthy volunteers serving as controls were also included. Thyroid stimulating hormone (TSH), fasting blood sugar (FBS) and tuberculin skin tests were performed for both groups. Results: Mean serum level of FBS in the patient group was significantly higher than the mean serum level of FBS in the control group (110.60 +/- 46.31 mg/dL versus 88.39 +/- 10.58 mg/dL, respectively, p=0.004). Mean serum level of TSH in the patient group was 3.43 +/- 2.73 mIU/L, which was not significantly different from the mean serum level of TSH in the control group (3.26 +/- 2.11 mIU/L, p=0.772). Four individuals in the patient group and only 1 in the control group had a positive tuberculin skin test. Conclusion: Granuloma annulare patients are better to be assessed for diabetes mellitus, but the relationship between this skin disease and thyroid disorders or tuberculin skin test still needs to be investigated.