Thyroid Dysfunction in Lichen Disorders: A Cross-Sectional Study of Clinical Associations in a North African Cohort

Background: Lichen disorders have been linked to thyroid dysfunction, but most studies treat them as a single entity, and data from North African populations with darker phototypes remain limited.
Objective: To evaluate thyroid dysfunction prevalence across clinical subtypes of lichen disorders in a North African cohort.
Methods: A cross-sectional study (retrospective and prospective, February 2023–February 2026) was conducted at CHU Ibn Sina, Rabat, Morocco, including 302 patients with confirmed lichen disorders. Thyroid dysfunction was defined as a previously diagnosed disorder or an abnormal thyroid assessment (TSH, FT4, anti-TPO, anti-Tg). Associations were assessed using Chi-square/Fisher’s exact tests and odds ratios (OR).
Results: Mean age was 52 years (IQR: 43–62); 93.7% were female. Frontal fibrosing alopecia (FFA) was the most frequent subtype (42.4%), followed by lichen planus pigmentosus (LPP, 38.4%) and classical lichen planus (23.5%). Thyroid dysfunction occurred in 14.6% of patients: hypothyroidism (10.0%), hyperthyroidism (3.6%), and isolated autoimmune thyroiditis (2.3%). FFA was the only subtype significantly associated with thyroid dysfunction (20.3% vs. 10.3%; p = 0.024, OR = 2.2), driven by hyperthyroidism (8.6% vs. 0%; p < 0.001). LPP showed a significantly lower hypothyroidism prevalence (4.3%; p = 0.010, OR = 0.29). Oral mucosal involvement more than doubled thyroid dysfunction prevalence (27.3%; p = 0.028, OR = 2.51).
Conclusion: Thyroid dysfunction is a significant, phenotype-specific comorbidity of lichen disorders. The novel FFA-hyperthyroidism association warrants confirmation in larger prospective studies, and supports systematic thyroid screening, particularly in patients with FFA or oral mucosal involvement.