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Body CT is not a useful imaging study in the detection of occult metastases in patients with primary melanoma. Although body CT commonly shows suspicious radiologic abnormalities in patients with early melanoma, these abnormalities most likely represent benign processes or a second primary tumor, rather than metastatic melanoma. The value of body CT in patients who present with nodal metastases needs further study.

Pulmonary infection in immunocompromised patients is frequently difficult to diagnose. Therapy for the more common pathogens differs greatly from that for infection with unusual opportunistic organisms. However, neither of these infectious agents offers specific radiographic signs. The authors report on 4 patients with acute leukemia and invasive aspergillosis whose radiographs demonstrated a distinctive feature of one or more air crescents within an area of pulmonary infiltrate. Autopsy studies correlated the radiographic changes with an infection due to Aspergillus species fungi. While the sign is not pathognomonic for Aspergillus infection, seen in a suitable host, it would suggest the possibility of invasive aspergillosis.

Medical records and radiographs of 103 adults with primary tuberculosis were reviewed. The shift toward delayed presentation appears to be related to decreasing childhood exposure and an increasing number of compromised hosts. Compared with classic "childhood" tuberculosis, there is a higher incidence of lower-lobe disease, but infiltrates also commonly involve the upper lobe or upper segments of the lower lobe. Adenopathy, cavitation, and tuberculoma are rare. If a pleural effusion is present and tuberculosis is suspected, pleural biopsy is mandatory. Adult respiratory distress syndrome can be a complication, particularly in miliary tuberculosis, and disseminated intravascular coagulopathy usually follows. A normal chest radiograph or clinical improvement of the patient with bed rest and penicillin does not exclude tuberculosis. Increased awareness of adult-onset tuberculosis on the part of radiologists could lead to a more rapid diagnosis and successful management.

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