Internal Medicine

0521779407-09 CUNY1086/Karliner 0 521 77940 7 June 4, 2007 21:13

720 Histoplasma Capsulatum

■Massively elevated serum ferritin levels may indicate disease, espe-

cially in HIV/AIDS patients

■CSF (with meningitis):

➣Pleocytosis: cell counts 10–100, lymphocyte predominance

➣Hypoglycorrhachia, elevated protein 80%

Specific Tests

■Cultures:

➣Sputum – 10–15% acute, 60% of cavitary disease, yield increases

with number of specimens

➣AIDS with pulmonary disease – 90% of bronchoscopy specimens

positive, BM and Blood cx 50% positive

➣Meningitis – 20–65% recovery

➣Pericardial/pleural disease – fluid low recovery, tissue better

■Antigen detection – urine (occ. serum): mainstay of diagnosis, 90%

of patients with PDH will be positive, 40% with cavitary disease, 20%

with acute disease. Excellent test for immunosuppressed

■Serology: Comp-fix (CF) 1:8 positive, 1:32 strongly suggests active

infection; four-fold rise in titer indicative of infection. False-positive

rate 15%, commonly observed with coccidioidomycosis or blasto-

mycosis.

Imaging (CXR)

■Acute: patchy pneumonitis that calcifies and hilar LAN (heavy expo-

sure leads to “buckshot” appearance). Ghon complex and pul-

monary calcifications with healed disease.

■Acute reinfection: numerous small nodules that are diffusely scat-

tered throughout both lung fields.

■Histoplasmoma: central core of calcium, rings of calcium, clusters

(“mulberry” calcifications)

■Cavitary disease: cavitary lesions in upper lobes, distinguish from

preexisting bullae

■Acute Progressive Disseminated Histo: patchy pneumonitis with

hilar node enlargement

differential diagnosis

■Acute pulmonary histo: distinguish influenza, other forms of

community-acquired pneumonia

■Mediastinal lymphadenopathy: often considered hematologic

malignancy when actually is histo

■Sarcoidosis difficult to distinguish