47-year-old women was admitted to the clinic for diagnosis of an incidentally X-ray detected enlargement of the medistinum shadow. In the past, the patient had been operated for lymphangioma of the right forearm. Chest computer tomography (CT) showed an abnormal mass in the front mediastinum with spherical structures, which density could indicate high-protein contents. In the right mammarian gland an oval cyst (23-15 mm), similar in character to the lesion in the mediastinum was found. The lymphangiomatic character of the lesion with the extension up to the superior aperture of the thorax was confirmed with magnetic resonans imaging (MRI). Due to the extensive changes and lack of symptoms, the patient was disqualified for surgical treatment and remains under further observation.