TABLE 3 ].

Differential Diagnosis

Differential Diagnosis	Clinical Features	Radiologic Features
Disseminated TB	Weeks to months of failure to thrive, fever of unknown origin, night sweats, organ dysfunction. Can have joint pains, neurologic manifestations, and adrenal insufficiency.	Reticulonodular opacities, cavitary lesion or widespread miliary nodules, and pleural disease; leptomeningeal involvement; spondylodiscitis.
Pneumoconiosis	Nonspecific clinical manifestations such as shortness of breath, decreased exercise tolerance, and nonproductive cough. In coal worker’s pneumoconiosis, black pigmented sputum can be expectorated.	Diffuse small nodules throughout the lungs, most common in the upper lobes. Calcified nodules and lymphadenopathy also are common.
Disseminated histoplasmosis	Exposure to endemic area, fever, respiratory symptoms, anorexia, and weight loss. Hepatosplenomegaly and lymphadenopathy are common. Neurologic symptoms less common, but when present, chronic meningitis is the most common manifestation.	Diffuse upper lobe predominant small pulmonary nodules, calcified lymph nodes or granulomas, hepatosplenomegaly, CNS ring enhancing lesions, and leptomeningeal involvement.
Disseminated coccidiomycosis	Exposure to endemic area. Malaise, fevers, respiratory involvement. Up to 50% have skeletal involvement. If there is neurologic involvement, then less likely to have other organ involvement.	Consolidation is the most common pulmonary finding; associated nodules, hilar lymphadenopathy, and pleural effusions; meningitis; lytic bone lesions.
Invasive aspergillosis	Solid organ transplant increases risk of disease. Fever, cough, sputum production, and dyspnea. Can also be asymptomatic. Hemoptysis can occur.	Nodular opacity or consolidation. Halo of hemorrhage may be seen around the nodule. Peripheral wedgelike areas of consolidation representing hemorrhagic pulmonary infarcts or direct invasion into adjacent chest wall or mediastinal structures.
Small-vessel vasculitis	Sinus disease, lower airway involvement with cough or hemoptysis, glomerulonephritis, ocular involvement, and cutaneous manifestations are common. Neurological symptoms related to lacunar infarcts, white matter lesions, large hemorrhages, and microbleeds.	Ground-glass opacity, consolidations, nodules with or without cavitation; CNS vasculitis.
Posttransplant lymphoproliferative disorder	Associated with EBV infection. Can occur anywhere from weeks to years after transplant. Symptoms diverse and related to type of disorder and location—could be related to mass effect, organ dysfunction, or lymphoma-related B symptoms.	Marked lymphadenopathy, masslike consolidation, or nodules; pleural effusion.
Sarcoidosis	Nonspecific clinical manifestations that can affect any organ system. Common symptoms include dry cough, weight loss, fatigue, night sweats, and erythema nodosum.	Variable. Hilar and mediastinal lymphadenopathy most common, could have parenchymal micronodules or airspace opacities.
Acute hypersensitivity pneumonitis	Fever, malaise, cough, weight loss, and dyspnea. If the exposure to the offending antigen is acute, symptoms will resolve after several days of antigen avoidance.	Upper and middle lobe predominant patchy ground-glass or nodular opacities in a bronchovascular distribution. Mosaic attenuation on expiratory cuts signifying air trapping.

EBV = Epstein-Barr virus.