PURPOSE: In endemic areas, up to 40% of solitary pulmonary nodules (SPN) are due to coccidioidomycosis and are difficult to distinguish from malignancy by imaging. The objective of this study was to determine if additional diagnostic information could be obtained from positron emission tomography (PET) in the evaluation of SPN due to coccidioidomycosis.
METHODS: We performed a retrospective review of all biopsied SPN at the Southern Arizona Veterans Affairs Health Care System between January 2008 and April 2010.
RESULTS: 173 pulmonary nodule biopsies were reviewed. 153 nodules (88%) were malignant and 20 were benign. Of the 20 benign nodules, 14 were confirmed to be coccidioidal (8%) and 6 were granulomatous without a specific diagnosis. 15 of 20 patients with benign nodules were Caucasians, 17/20 (85%) were smokers, and 7/20 (35%) had a history of immunosuppression. Mean age was 63.3 years and all were male. All had negative coccidioidomycosis serology. PET was performed in 10 of 20 cases with confirmed non-malignant SPN. Seven were done in the coccidioidomycosis group and 3 in the granuloma group. Six of the 7 PET scans (86%) performed in the coccidioidomycosis group were positive and so were 2 of the 3 in the granuloma group. Of the 6 positive PET scans in the coccidioidomycosis group, 4 patients (67%) had both PET-positive lung nodule and mediastinal nodes while 2 patients had PET-positive lung nodule but PET-negative mediastinal nodes. Among the 2 positive PET scans in the granuloma group, 1 patient had PET-positive lung nodule only and the other had PET-positive mediastinal nodes only.
CONCLUSIONS: In this endemic area, fewer than 10% of biopsied SPN were due to coccidioidomycosis. PET was positive in 86% of these patients with uptake in both the nodule and mediastinum. PET did not reliably distinguish between malignant and non-malignant pulmonary nodules.
CLINICAL IMPLICATIONS: Although subject to bias, PET does not appear to be useful in the evaluation of solitary pulmonary nodules due to coccidioidomycosis.
DISCLOSURE: The following authors have nothing to disclose: Oluwole Onadeko, Margaret Rennels, Travis Walsh, Kenneth Knox, Neil Ampel
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