Lichen Planus Pigmentosus: A study for association of Thyroid Dysfunction.

Background Lichen planus pigmentosus (LPP) is considered a chronic and progressive variant of lichen planus. Although pigmentation occurs in the sun exposed areas, the etiology remains unknown and there are no appropriate treatment guidelines. Association with thyroid disorder has been described in various disorders of pigmentation. Objective The objective of this study was to find the association between LPP and thyroid dysfunction. Method A total of 54 clinically diagnosed cases of LPP and 54 age and sex matched healthy control volunteers were included in this case control study. Thyroid function test and thyroid peroxidase antibody were analysed to determine the probable association between thyroid diseases and LPP. Result Seventeen (31.7%) patients had biochemical evidence of hypothyroidism and 3 had hyperthyroidism among the diseased group. Among the control group two persons were tested positive for hypothyroidism (c2 = 0.34; p <0.05). Similarly, the levels of thyroid peroxidase antibody in the LPP patients were found to be significantly higher than those of controls (p <0.05). Conclusion Thyroid disorder was found to be an associated factor in LPP. Hence, we recommend routine thyroid function tests in patients with LPP. Further research is warranted among large number of patients to elucidate the exact association.