A diffuse angiomatosis affecting thoracal organs is a rare, frequently fatal disorder occurring mainly in childhood. The definite diagnosis is usually made by autopsy. A specific treatment does not exist. In the case report presented here we describe the course of an 37-year old patient presenting initially with dyspnea and hemoptysis. Radiological investigations showed a mass lesion in the anterior superior mediastinum, bihilar masses and a periesophageal mass with soft tissue density and a pericardial effusion. Bilateral interstitial infiltrations were also present. CT-guided mediastinal biopsies and bronchial mucosal biopsies were nonspecific. Open-lung biopsy revealed the diagnosis of an extensive diffuse angiomatosis affecting mediastinum, pericardium and pleura. During the 18-month monotherapy with interferon-alpha 2a the patient showed significant improvements of clinical as well as laboratory and radiological parameters. The presented case confirms the experience of several authors, that the diagnosis of a diffuse thoracal authors can only be made by open lung biopsy or autopsy. The presented case also underlines the possibility of a palliative therapy of aggressive angiomatous diseases with interferon-alpha 2a.