A 30 years old male was referred to the authors' department with complaints of a fever (39,5ºC), non-productive cough, myalgias and fatigue for 10 days before his admission to the hospital. Upon admission, a chest radiograph was performed showing bilateral hilar lymphadenopathy accompanied by fluffy nodular and micronodular opacities predominating in the middle lung fields (figure 1). The patient received one course of antibiotics for common bacterial pathogens, before he sought our medical assistance, with no remission of the above-mentioned symptoms. He was an active smoker (10 pack/years). He worked as an employee in an office in a private company. He had been in good health previously.A thorough physical examination and laboratory evaluation at the time of the admission was normal. Briefly, there were no abnormal findings from the examination of the respiratory system, and there were no signs of involvement of peripheral lymph nodes, hepatic disease or skin lesions. Complete blood count and standard serum biochemistry tests were normal. Serum angiotensin converting enzyme (SACE) was within normal limits (55 U/L). Serum and urine calcium levels were normal. Laboratory tests for collagen-vascular diseases (i.e. C3 and C4 complement components, antinuclear antibodies, c and p ANCA), as well as erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were normal. Serologic tests for EbsteinBarr virus (EBV), cytomegalovirus (CMV) and Toxoplasma and Brucella were negative. Additionally, serologic tests for hepatitis A, B and C, as well as for human immunodeficiency virus were negative. Arterial blood gases were normal. Electrocardiogram and echocardiogram were normal, excluding any heart involvement. An ultrasonographic exKeywords: Fever, bilateral hilar lymphadenopathy, nodular opacities, GLUS.