Acquired tumors of lymphatic vessels are rare. Clinically, progressive lymphangioma usually appears as circumscribed plaques of small to medium size. In contrast, our case of a 13-year-old boy demonstrates a case of progressive lymphangioma with a solitary large indurated plaque. No extracutaneous manifestation was found. Systemic therapy with corticosteroids and methotrexate resulted in an improvement of the patient's condition. Dependent on clinical course and appearance of the disease, therapy with mTOR inhibitors may be considered as a therapeutic option.