Recurrent Facial Miliaria Crystallina Revealing Underlying Hyperthyroidism: A Report of Two Cases

Miliaria crystallina is a superficial sweat retention disorder typically associated with fever, heat exposure, or excessive sweating and usually follows a transient course. Recurrent facial involvement without identifiable triggering factors is uncommon. We report two postmenopausal women aged 46 and 54 years presenting with recurrent asymptomatic facial eruptions evolving over several months. Dermatological examination revealed multiple superficial translucent vesicles localized predominantly to the forehead and cheeks. Both patients reported associated heat intolerance and excessive sweating. Laboratory investigations demonstrated suppressed thyroid-stimulating hormone levels with elevated thyroid hormone levels, leading to the diagnosis of hyperthyroidism. Following initiation of antithyroid therapy, the frequency of cutaneous flares progressively decreased, with subsequent cessation of recurrences and improvement in sweating and heat intolerance. Hyperthyroidism-induced hyperhidrosis may contribute to eccrine duct obstruction and promote the development of miliaria crystallina. Recurrent facial miliaria crystallina may represent an unusual cutaneous presentation associated with hyperthyroidism. Recognition of this atypical presentation may facilitate identification and appropriate management of previously unrecognized thyroid dysfunction.