The role of gallium-67 scan in defining the extent of disease in an endemic deep mycosis, paracoccidioidomycosis: a predominantly multifocal disease

The tools currently used to evaluate the extent of paracoccidioidomycosis (PCM) may be of limited value in detecting subclinical lesions. The aim of this study was to verify the role of gallium-67 whole-body scan in evaluating the extent of disease of 65 patients with active PCM. The 67Ga scan findings were compared with the results of clinical evaluation, chest radiography and/or high-resolution computed tomography (CT), abdominal ultrasound (US) or CT, laryngoscopy, CT or magnetic resonance imaging (MRI) of the head, and technetium-99m methylene diphosphonate bone scan, obtained before treatment. Clinically unsuspected lesions were detected by imaging procedures in 21 patients (32%), mainly in the lungs (n=11), adrenals (n=6), and superficial (n=3) and deep lymph nodes (n=14). 67Ga scan detected 100% of the cases with subclinical involvement in the lungs. Scintigraphy was superior to chest radiography in demonstrating lung disease (94% vs 81%). The lymphatic lesions were demonstrated by 67Ga scan in all the clinically suspected cases and in nearly all unsuspected cases, and also revealed more extensive involvement than was clinically suspected in many of them. There was good agreement between 67Ga scan and the other imaging procedures for the initial detection of thoracic and abdominal lymph nodes and bone involvement. 67Ga imaging detected most cases of laryngopharyngeal disease with active inflammatory lesions found at indirect laryngoscopy. On the other hand, 67Ga scan failed to demonstrate most of the adrenal and CNS lesions detected by abdominal US/CT and head CT/MRI. In conclusion, 67Ga imaging is a useful tool for evaluating the location and extent of suspected and unsuspected lesions in PCM. It could serve as a screening method before the use of other diagnostic procedures, particularly in the detection of lung, superficial and deep lymph node and bone involvement.