대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Pulmonary histoplasmosis

Radiologic Findings

Well defined multiple nodules with variable sizes are scattered in both lung fields. Nodules show low attenuation in their central portion, and some of them have cavitation.

H-E stain: There are air spaces (arrowheads), and histiocytes which contain yeast formed fungi in their cytoplasm (arrows).
GMS stain: There are Histoplasmosis capsulatum which are stained black at GMS (Gomori Methenamine Silver) stain.

HE stain

GMS stain

Brief Review

Histoplasmosis is caused by the dimorphic fungus, Histoplasma capsulatum. Infections are acquired through inhalation of airborne spores.
It is endemic in the Mississippi and Ohio river valleys, south America and Africa. It is very rare disease in Korea, there are only 3 case reports.
The majority of infected persons have an asymptomatic, self-limiting illness in 99.5% of infected individuals. The most common clinical presentation is solitary nodule on chest radiographs or CT images. These nodules correspond histologically to an encapsulated focus of necrotizing granulomatous inflammation, and show central (target) or diffuse calcification radiologically, as a result of dystrophic calcification of necrotic material. CT is also very useful in the evaluation of patients with suspected fibrosing mediastinitis.
Chronic disease of histoplasmosis, which mimics tuberculosis, occurs almost exclusively in patients with chronic obstructive pulmonary disease. It presents radiologically as patchy areas of consolidation, nodules, sometimes with cavitation, involving mainly the apical and posterior segments of the upper lobes.
After heavy exposure or in patients with deficient cell-mediated immunity, radiographs can show widely disseminated, diffuse, fairly discrete nodular shadows throughout the lungs.

References

1.Gurney JW, Conces DJ. Pulmonary histoplasmosis. Radiology 1996;199:297-306
2.Salzman SH, Smith RL, Aranda CP. Histoplasmosis in patients at risk for the acquired immunodeficiency syndrome in a nonendemic setting. CHEST Journal 1988;93:916-921
3.Jeong HW, Sohn J-W, Kim MJ, Choi JW, Kim CH, Choi S-H et al. Disseminated histoplasmosis and tuberculosis in a patient with hiv infection. Yonsei medical journal 2007;48:531-534

Keywords

Lung, infection, Fungal infection,