In heart failure localized interlober pleural effusion is rare but well-known finding. But there is not enough case reports in the literature. This radiological finding seems like a mass and undergoes resolution quickly, It is also known as vanishing tumor, pseudotumor or phantom tumor. It is difficult to estimate the incidence due to the small number of reported cases. Determination of the mass appearance in chest X-ray should be reminded the phantom tumor especially in heart failure patient. This diagnosis would prevent unnecessary expensive diagnostic procedures, wrong diagnosis and treatment. Copyright (C) 2017 The Emergency Medicine Association of Turkey. Production and hosting by Elsevier B.V. on behalf of the Owner.