Acquired Ichthyosis and Rhabdomyolysis as Unusual Manifestations of Severe Hashimoto’s Hypothyroidism: A Case Report

Acquired ichthyosis is an uncommon dermatological manifestation that may occasionally reveal an underlying systemic disorder, including endocrine diseases. We report the case of a 31-year-old man with no significant dermatological or family history, admitted for severe asthenia, diffuse myalgia, dysphonia, and progressive psychomotor slowing evolving over several months. Clinical examination revealed marked acquired ichthyosis characterized by thick polygonal scales predominantly affecting the extensor surfaces, associated with bradycardia and cognitive slowing. Laboratory investigations demonstrated profound hypothyroidism with thyroid-stimulating hormone (TSH) levels >100 mIU/L and markedly decreased free thyroxine (FT4 = 0.45 ng/dL). Creatine phosphokinase (CPK) levels were markedly elevated (7245 IU/L), consistent with rhabdomyolysis, in the absence of trauma, intense physical exertion, or myotoxic drug exposure. Autoimmune work-up showed strongly positive anti-thyroid peroxidase (>1200 IU/mL) and anti-thyroglobulin antibodies (300 IU/mL), confirming Hashimoto’s thyroiditis. In the absence of any alternative cause, both the muscular involvement and acquired ichthyosis were attributed to severe thyroid hormone deficiency. Treatment with levothyroxine resulted in progressive clinical improvement, normalization of CPK levels, and marked regression of skin lesions. This case highlights the importance of considering severe hypothyroidism in the diagnostic work-up of acquired ichthyosis associated with muscular manifestations.