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.