Correct!
5. Treat for mycobacterial infection and observe
Treating for mycobacterial infection and observing is reasonable. Therapy for fungal infection is not indicated as all studies to date for possible fungal infection have failed to disclose such. At this point, it is reasonable to entertain the notion of obtaining a larger tissue sample in the hopes of providing a definitive diagnosis, but it remains unclear which of the two lesions, or, if one were exceedingly aggressive, both lesions, should be resected. Instead, a potential benign diagnosis that can be targeted with therapy has been suggested for the left apical lesion, so it is reasonable to institute such therapy and observe closely. The right lower lobe lesion shares some histopathological characteristics in common with the left apical lesion, although the right lower lobe lesion should be regarded as indeterminate, as no definitive histopathological diagnosis, either benign or malignant, has been established. Nevertheless, the likelihood of malignancy in this lesion has been reduced substantially in light of the lower tracer utilization at 18FDG-PET scan and the lack of malignancy at histopathological examination following a successful percutaneous transthoracic needle biopsy procedure, so surgical intervention, while not unreasonable, may be deferred in favor of imaging surveillance. Because the left apical lesion will be followed closely with CT, the right lower lobe mass can be reassessed simultaneously with the same CT scan obtained to follow the left apical mass.
Some prior records were located and the patient subsequently recalled right parotic surgery for resection of a benign pleomorphic adenoma. The patient was started on clarithromycin, ethambutol, and rifampin for treatment of the MAC obtained from the left apical mass. He subsequently underwent repeat thoracic CT (images not shown) one month after the biopsy of the right lower lobe mass and institution of the antibiotic therapy, which showed no clear change in the left apical or right lower lobe lesions. Repeat thoracic CT approximately 6 months later (Figure 4) showed decrease in size of the left apical lesion but no clear change in the right lower lobe lesion.
Figure 4. Panels A-F: Axial enhanced thoracic CT displayed in lung windows 6-7 months following biopsy of the left upper lobe mass. Lower panel: video of axial thoracic CT scan.
Given the data available, which of the following represents the most appropriate management step for the evaluation of this patient? (Click on the correct answer to proceed to the tenth and final page)