A 48-year-old automobile mechanic in Kentucky in good previous health presented with a 2-month history of cough, fever, weight loss, and fatigue. His x-ray showed cavitary pneumonia and a coin lesion in the right upper lobe. Smear and culture of a bronchoalveolar lavage revealed evidence of a fungal infection.
A. Aspergillosis B. Histoplasmosis C. Cryptococcosis D. Pneumocystis E. Coccidioidomycosis
Histoplasmosis-https://upload.wikimedia.org/wikipedia/commons/thumb/a/ad/chest_x-ray_acute_pulmonary_histoplasmosis_phil_3954.jpg/459px-chest_x-ray_acute_pulmonary_histoplasmosis_phil_3954.jpgepidemiology histoplasma capsulatum is found throughout the world. it is endemic in certain areas of the united states, particularly in states bordering the ohio river valley and the lower mississippi river. it is also common in caves in southern and east africa. positive histoplasmin skin tests occur in as many as 90% of the people living in areas where h. capsulatum is common, such as the eastern and central united states. disease mechanism h. capsulatum grows in soil and material contaminated with bird or bat droppings (guano). the fungus has been found in poultry house litter, caves, areas harboring bats, and in bird roosts (particularly those of starlings). the fungus is thermally dimorphic: in the environment it grows as a brownish mycelium, and at body temperature (37 °c in humans) it morphs into a yeast. the inoculum is represented principally by microconidia that, once inhaled into the alveolar spaces, germinate and then transform into budding yeast cells. histoplasmosis is not contagious, but is contracted by inhalation of the spores from disturbed soil or guano. diagnosis histoplasmosis can be diagnosed by samples containing the fungus taken from sputum, blood, or infected organs. it can also be diagnosed by detection of antigens in blood or urine samples by elisa or pcr. it can also be diagnosed by a test for antibodies against histoplasma in the blood. histoplasma skin tests indicate whether a person has been exposed, but do not indicate whether they have the disease. formal histoplasmosis diagnoses are often confirmed only by culturing the fungus directly. cutaneous manifestations of disseminated disease are diverse and often present as a nondescript rash with systemic complaints. diagnosis is best established by urine antigen testing. blood cultures may take up to 6 weeks for diagnostic growth to occur and serum antigen testing often comes back with a false negative before 4 weeks of disseminated infection if symptoms of histoplasmosis infection occur, they will start within 3 to 17 days after exposure; the average is 12–14 days. most affected individuals have clinically silent manifestations and show no apparent ill effects. the acute phase of histoplasmosis is characterized by non-specific respiratory symptoms, often cough or flu-like. chest x-ray findings are normal in 40–70% of cases. chronic histoplasmosis cases can resemble tuberculosis; disseminated histoplasmosis affects multiple organ systems and is fatal unless treated. while histoplasmosis is the most common cause of mediastinitis, this remains a relatively rare disease. severe infections can cause hepatosplenomegaly, lymphadenopathy, and adrenal enlargement. lesions have a tendency to calcify as they heal. ocular histoplasmosis damages the retina of the eyes. scar tissue is left on the retina which can experience leakage, resulting in a loss of vision not unlike macular degeneration