Tehran University of Medical Sciences Acta Medica Iranica 0044-6025 53 12 2015 10 20 789 792 EN Vitorino Modesto dos Santos Department of Internal Medicine, Armed Forces Hospital and Catholic University, Brasília-DF, Brazil . Christiane Aires Teixeira Department of Pneumology, Armed Forces Hospital, Brasília-DF, Brazil. Ana Carla Andrade Almeida Department of Pneumology, Armed Forces Hospital, Brasília-DF, Brazil. Alessandra Maria Rodrigues Oliveira Santos Department of Internal Medicine, Armed Forces Hospital and Catholic University, Brasília-DF, Brazil . Kátia Rejane Marques Brito Department of Internal Medicine, Hospital of West, Barreiras-BA, Brazil. Valerio Alves Ferreira Department of Radiology, Armed Forces Hospital, Brasília-DF, Brazil. 2015 10 20 Yellow nail syndrome (YNS) is an uncommon condition characterized by nail changes, lymphedema, in addition to pulmonary disorders and pleural effusion. Pericarditis and non-cardiac disorders can evolve with pericardial effusions including autoimmune conditions, hypothyroidism, malignancies, tuberculosis, and uremia. A 72-year-old Brazilian woman under treatment for arterial hypertension and hypothyroidism was admitted with pericarditis and pericardial effusion concomitant with yellow nail syndrome. She denied tobacco smoking, alcohol abuse, and similar disorders in her family. Clinical and complementary evaluation ruled out infectious diseases, malignancies, and autoimmune disorders as etiologic factors in this case. Hypothyroidism is a well-known cause of pericardial effusion, the vast majority in the absence of pericarditis, and has been described as an associated condition in some individuals with YNS. Case studies might contribute to better understanding of these causal or casual relationships. https://acta.tums.ac.ir/index.php/acta/article/view/5016 https://acta.tums.ac.ir/index.php/acta/article/download/5016/4688