Mastocytosis refers to a group of diseases characterized by a clonal proliferation and accumulation of mast cells in one or more tissues/organs with different clinical presentations. In children, limited cutaneous forms of mastocytosis are rather frequent, while systemic mastocytosis is rare. The diagnosis of cutaneous mastocytosis is based on clinical findings and histopathology. We present a patient who developed skin lesions at the age of 18 months. Clinical findings, confirmed by histopathology, were consistent with diffuse cutaneous mastocytosis. The follow-up period was 7 years. The treatment included oral antihistamines in combination with mast cell stabilizers, mild topical steroids and avoidance of friction. During the follow-up period, there were no signs of systemic involvement, and the quality of life was preserved, despite the large surface of affected skin. This case report should increase the awareness and knowledge of clinicians about this rare form of cutaneous mastocytosis in the pediatric population.