Association of oral lichen planus with thyroid disease in a Finnish population: a retrospective case-control study.

OBJECTIVE: The objective of this study was to estimate the association between the history of thyroid disease and the prevalence of oral lichen planus (OLP)/oral lichenoid lesions (OLL).

STUDY DESIGN: This was a retrospective case-control study using data from the medical records of 222 OLP/OLL patients and 222 age- and sex-matched controls who had visited the Institute of Dentistry, University of Oulu or the Oral and Maxillofacial Department, Oulu University Hospital, from 1992 to 2001. Clinical characteristics of OLP/OLL lesions, other oral mucosal diseases, presence of cutaneous LP, history of allergies, medical history, and the use of regular medications were recorded. The relative odds of OLP, OLL, and OLP/OLL associated with selected patient characteristics were estimated by logistic regression.

RESULTS: History of any thyroid gland pathosis was found in 15% (n=22) of the 152 cases with OLP, in 13% (n=9) of the 70 cases with OLL, and in 8% (n=18) of the control subjects; the estimated odds ratios (with 95% confidence intervals) being 2.12 (1.06 to 4.21) for OLP and 1.57 (0.62 to 3.73) for OLL. When confined to hypothyroidism only, this disease was found in 10% (n=15) of the OLP cases, 9% (n=6) of the OLL cases, and 5% (n=11) of the controls; the estimated odds ratios being 2.39 (1.05 to 5.61) for OLP and 1.73 (0.56 to 4.90) for OLL.

CONCLUSION: The association of OLP/OLL and thyroid disease, especially between hypothyroidism and OLP, calls for further investigations in other populations and into the possible mechanisms behind this association.