Pulmonary lymphatic drainage to the mediastinum based on computed tomographic observations of the primary complex of pulmonary histoplasmosis

Chronic Cavitary Pulmonary Histoplasmosis in an Immunocompetent Patient

Histoplasma capsulatum is a fungal organism that causes systemic histoplasmosis. It is commonly asymptomatic in healthy immunocompetent individuals. The clinical symptoms of chronic cavitary histoplasmosis are typically seen in the immunodeficient population, particularly in smokers with pre-existing structural lung disease. We report a case of chronic cavitary histoplasmosis in an immunocompetent patient from an endemic area without pre-existing structural lung pathology. She presented complaining of right hypochondrial pain and had no history of respiratory symptoms nor history suggestive of immunosuppression, tuberculosis, or recent travel. CT scan revealed a cavitary lung lesion and a hilar mediastinal mass. Biopsies obtained by bronchoscopy revealed signs of necrosis, granulomas, and the presence of fungal organisms consistent with histoplasmosis. Histoplasma antibodies by complement fixation for yeast antibodies test were positive establishing the diagnosis of chronic cavitary pulmonary histoplasmosis (CCPH). She was then started on itraconazole with good tolerance. On follow-up three months later, a chest CT done along with measurement of inflammatory markers and liver enzymes demonstrated complete clinical recovery. This case emphasizes the importance of expanding our current understanding of the clinical presentation and manifestations of histoplasmosis beyond the conventional assumption that severe disease only affects immunocompromised individuals.

F-18-FDG-avid lymph node metastasis along preferential lymphatic drainage pathways from the tumor-bearing lung lobe on F-18-FDG PET/CT in patients with non-small-cell lung cancer

OBJECTIVE

F-18-FDG-avid lymph node (LN) metastasis may preferentially occur along the lymphatic drainage pathway (LDP) from the tumor-bearing lobe in patients with non-small cell lung cancer (NSCLC) on FDG PET/CT. This study evaluated whether the identification of metastatic LNs according to LDP-based visual image interpretation can improve LN staging on FDG PET/CT in these patients.

METHODS

FDG PET/CT study was performed in 265 patients with NSCLC. The presence and LN station of metastatic LNs were determined by surgery or the clinical course. In the LDP-based interpretation, FDG-avid LNs, which were located along the preferential LDP from each tumor-bearing lobe and visually more intense in FDG uptake compared with the remaining LNs straying away from the preferential LDP, were diagnosed as metastatic. The result was compared with the quantitative method using a cutoff value of 2.5 for the maximum standardized uptake value.

RESULTS

Of the total 1031 mediastinal and hilar LN stations with FDG-avid LNs in 265 patients, 179 stations in 66 patients were metastatic and the remaining 852 were benign. All the metastatic LN stations except for 2 stations showing skip metastasis were located along the main preferential LDP or another preferential LDP via a direct anatomic pathway from each tumor-bearing lung lobe. The specificity, accuracy, and PPV for identifying metastatic LN stations by LDP-based interpretation were 97.9, 95.7 and 89.5 %, respectively, which were significantly greater compared with those of 92.7, 90.8 and 70.3 % by the SUV-based method (P < 0.001).

CONCLUSIONS

The present study shows that FDG-avid LN metastasis preferentially occurs along the LDP from the tumor-bearing lobe in NSCLC patients. LDP-based visual image interpretation on FDG PET/CT can improve LN staging in these patients.