Abstract: Olmsted syndrome (OS) is a rare genodermatosis. The disease is debilitating and progressive keratoderma and auto-amputation of digits can prevent patients from grasping and walking, and confine them to a wheelchair. New therapeutic options are therefore crucial and are expected from a better understanding of the disease mechanisms. The inventors show an abnormal mTOR pathway activation in OS lesional skin. Topical treatment with 1% Sirolimus shows good tolerance and partial but real efficacy on budding, inflammatory and hyperkeratotic lesions of the sole was observed in the treated patient. Accordingly, the present invention relates to a method of treating Olmsted syndrome in a patient in need thereof comprising administering to the patient a therapeutically effective amount of an mTOR inhibitor.