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Pulmonary Histoplasmosis


Clinical Features

Symptomatic Pulmonary Histoplasmosis: This fungal lung infection is notably linked to inhalation of dust ridden with fungal spores from bird or bat droppings from excavation, construction, or cleaning of farm buildings. Less than 5% of those exposed to H. capsulatum develop symptoms. Often the symptoms present weeks following exposure and are mild in nature. On radiological exam, the lung fields will show focal infiltrates and mediastinal or hilar lymphadenopathy but may also be normal. Histoplasmosis should be considered as a differential diagnosis for CAP that does not respond to empirical antibacterial therapy. The most common symptoms include fever, chills, headache, myalgias, anorexia, cough, and pleuritic chest pain (Kauffman, 2020). The physical examination is typically unremarkable with potential for fever, rales, and evidence of consolidation by percussion or tactile fremitus. 

Acute Diffuse Pulmonary Histoplasmosis: This type of H. capsulatum infection occurs following a heavy exposure to soil that is saturated with droppings from birds or bats. On x-ray, diffuse reticulonodular pulmonary infiltrates are present and the disease can progress quickly to a respiratory emergency. Treatment is recommended for this level of infection and following recovery, the patient may complain of symptoms of shortness of breath and exhaustion for months. 

Chronic Pulmonary Histoplasmosis: The chronic nature of a H. capsulatum infection correlates with chronic lung disease. These patients often have a chronic productive cough, dyspnea, chest pain, fatigue, fevers, and sweats (Kauffman, 2020). X-rays or CT scans reveal fibrotic apical infiltrates with cavitation and the findings are alike those with reactivation tuberculosis. With this infection, the cavities continue to grow and gravitate towards new areas of the lung and can result in complications such as fistulas. Of clinical importance is the disproportionate level of inflammatory response in the lung fields. It is critical to evaluate for both tuberculosis and histoplasmosis for proper treatment. Potential complications complicate treatment and require evaluation and treatment. Due to the prevalence of tobacco abuse in these patients, lung cancer should be considered in all patients that have nodular lesions that are not responsive to treatment or that spontaneously develop during the course of treatment. 

Broncholithiasis: Calcification of the lymph nodes and pulmonary nodules may occur within several years in adults. Occasionally, the calcification can cause damage to the bronchi leading to chronic cough, wheezing, hemoptysis, fever, chills, purulent sputum, or expectoration of gravel-like stones (Kauffman, 2020).

Risk Factors

Testing

Diagnosis

Treatment

Precautions, Identification, & Prevention

References