Applied Radiology

Prepared by Robert D. Pugatch, MD and Stuart E. Mirvis, MD, FACR, Department of Radiology, University of Maryland School of Medicine, Baltimore, MD.

CASE SUMMARY

A 31-year-old man from Western Maryland presented with recurrent hemoptysis of a 2-month duration.

DIAGNOSIS

Histoplasmosis with broncholithiasis

IMAGING FINDINGS

The frontal and lateral chest radiographs show a few scattered nodules with focal calcification in the right hilar area (figure 1). There is fullness of the hila on the lateral view. There is no evidence of lung consolidation or pleural effusion. The CT image viewed in lung windows shows scattered calcified nodules bilaterally with slight hypodensity in the right middle lobe (figure 2A). The CT image in soft-tissue windows (figure 2B) demonstrates a soft-tissue mass with dense central calcification located in the middle mediastinum, anterior to the vertebral body and surrounding the right intermediate bronchus. This finding is consistent with calcified and enlarged hilar and mediastinal lymph nodes. The enlarged lymph nodes are restricting the right intermediate bronchus with possible erosion into the airway by calcification. The pericardium is normal.

DISCUSSION

Histoplasmosis is caused by the organism Histoplasma capsulatum, which is endemic in the central United States and is found in soil excrement of birds (especially pigeons) and bats. Within endemic areas, 80% of the population test positive for histoplasmosis, but most remain asymptomatic. ¹ Inhalation of spores results in a localized infection of the lung that will migrate to involve the hilar and mediastinal lymph nodes, and eventually to the liver and spleen. ¹ Usually the organism is destroyed with no residual infection, but a scar or focal calcification may remain.

There are a wide variety of radiologic manifestations of histoplasmosis. The acute phase is characterized by single or multiple areas of consolidation and, possibly, associated hilar or mediastinal adenopathy. This usually resolves without treatment within weeks to months. Radiographically, there may be complete clearing, or a focus of calcification may persist. The epidemic form shows multiple discrete nodules throughout both lungs and may be associated with hilar adenopathy. When the nodules and lymph nodes begin to heal, they become calcified. A third radiographic pattern consists of a histoplasmoma (solitary granuloma), which is a well-defined necrotic focus of infection surrounded by an inflammatory reaction usually found in the lower lobes.

Complications from calcified lymph nodes include fibrosing mediastinitis and broncholithiasis. ^1,2 Fibrosing mediastinitis is due to the effects of large calcified lymph nodes and a surrounding fibrotic reaction that constrict and encase important mediastinal structures. ^1,2 Broncholithiasis occurs when calcified nodes erode into a bronchus, which can lead to unexplained chronic cough, hemoptysis, distal atelectasis, and distal lung parenchymal infection. ² A differential diagnosis for broncholithiasis includes tuberculosis, actinomycosis, coccidiodomycosis, crytococcosis, and silicosis.

In the present case, the patient underwent an emergent right pneumonectomy for an episode of uncontrollable life-threatening hemoptysis.