FDG-PET/CT Demonstrates Superior Detection of Multiorgan Involvement in Paracoccidioidomycosis Compared With Conventional Staging.

Abstract

Background: Paracoccidioidomycosis (PCM) is a neglected systemic mycosis in which accurate staging is critical but challenging with conventional methods. This study evaluated 18F-FDG PET/CT compared with standard evaluation for PCM staging and assessed its impact on disease severity classification.

Methods: Thirty-four patients with confirmed PCM (treatment-naïve or with suspected treatment failure) underwent conventional staging and whole-body 18F-FDG PET/CT. Disease severity was classified as mild, moderate, or severe. PET/CT images were analyzed qualitatively and quantitatively (SUVmax, TMLV, TLG).

Results: PET/CT detected more than twice as many lesions as conventional evaluation (150 vs 62; mean 4.4 ± 1.6 vs 1.8 ± 0.9 affected organ systems per patient), with statistically significant superiority for lymph node, pulmonary, and adrenal involvement (McNemar's test, P < .05). PET/CT reclassified 97% of patients as multifocal versus 59% by conventional staging and produced a significant unidirectional shift toward higher severity-the proportion classified as severe increased from 70.6% to 91.2% (P = .016). Patients with suspected treatment failure showed significantly lower TMLV and TLG than treatment-naïve patients (P < .05). Quantitative PET parameters correlated with serological titers and inflammatory markers (P < .05), and PET/CT detected four times as many sites as gallium-67 scintigraphy.

Conclusions: 18F-FDG PET/CT systematically reveals greater disease burden than conventional evaluation in PCM, reclassifying most patients toward higher severity with direct implications for treatment duration and follow-up. Where available, it should be considered an important complementary modality for initial disease assessment.