Bronchiolitis obliterans organizing pneumonia (BOOP) represents a kaleidoscope of concepts and morphologies, often being confused with a series of conditions, among which the most feared are Hodgkin's lymphoma and bronchioloalveolar carcinoma. We shall present the case of a 56-year-old patient, diagnosed in August 2013 with a pulmonary tumour of the right upper lobe, which was CTstaged - T4N0M0 (IIIA), who underwent a video-assisted thoracotomy for histopathological confirmation. A mediastino-pulmonary formation had been detected intraoperatively and multiple biopsies had been collected. The information brought by the histopathological examination suggested the presence of 2 synchronous pathologies, namely: the mediastinal biopsy showed an advanced degree of dense, compact fibrosis and the pulmonary biopsy highlighted the presence of granulation tissue and Masson bodies in the distal airspace with destruction of vascular and alveolar structures, an aspect which was compatible with organizing pneumonia (BOOP). Once a diagnosis was established, an oral corticosteroid therapy was initiated (Prednisone 30 mg/day) over a period of one month, but the symptomatology of the patient worsened. A new thoracic CT carried out in November 2013 highlighted the progression and extension of the paramediastinal tumoral formation, exhibiting central necrosis and invading the mediastinal vessels, causing their compression (superior vena cava syndrome) associated with multiple mediastinal and hilar adenopathies. The non-favorable evolution and the extensive array of conditions that may mimic the BOOP histopathological pattern have been the key elements, which were the basis of our persistence in getting a real diagnosis. Therefore, in this respect, the biopsy parts performed by thoracotomy were sent for immunohistochemical testing. The CD30 and CD15 positive markers distinctive for Reed-Sternberg cells allowed the diagnosis of Hodgkin's lymphoma.