A 73 year-old man was referred by his general practitioner to our ambulatory for worsening dyspnea. He also reported substantial weight loss (almost 20 kg during the last three months), new onset dysphonia and dry cough. The patient’s medical history also included a former tobacco addiction, arterial hypertension and dyslipidemia. There was not history of cardiomiopathy. Electrocardiogram, showed: sinus rhythm, 60/min with inferior and anterior-lateral abnormality of repolarization. No laboratory exams were available at the first visit. An echocardiogram was performed, showing: marked septal hypertrophy (IVSd= 23 mm), septal hypokinesia, with an ejection fraction at lower limits of normality (EF= 54%), neither systolic anterior motion of the mitral valve. Minimal pericardial effusion was seen. We required a CT scan of the chest, that showed a large (5x8x11cm) mass in the left upper lobe with ipsilateral mediastinal lymphadenopathy. The mass directly extended into the mediastinum with infiltration of pericardial leaflet, left atrium and the left wall of the aortic arch. A hypodense formation of approximately 4 cm in the interventricular septum in the apical portion was reported. PET-CT with FDG was performed, which documented hypercaptation of the radioactive tracer at the level of the above-mentioned lesions. The patient underwent fine-needle aspiration biopsy of the lung mass and the histological examination led to the diagnosis of squamous cell carcinoma of the lung. Systemic treatment with carboplatin plus placlitaxel and pembrolizumab was subsequently started. A cardiac CMR was performed, which documented an area of 30x17x31 mm located at the septal (mid-apical portion), apex and parapical portion of the free wall of the right ventricle with transmural extension. At this area, extensive late gadolinium enanchement (LGE) at marginal level with a central non-capillary core and hyperintense in T2 sequences (compatible with central necrotic lesion). The pericardium also showed LGE and a mild pericardial effusion (maximum 8 mm); left atrium involvement, seen on CT, was not documented . After he completed the third cycle of CHT, at 5 months from the diagnosis, the echocardiogram showed a substantial disappearance of the mass infiltrating the interventricular septum without evidence of pericardial effusion. The ecg was substantially unchanged. The patient stopped carboplatin and paclitaxel after 3 cycles and kept maintenance pembrolizumab still ongoing.