Internal Medicine

0521779407-C04 CUNY1086/Karliner 0 521 77940 7 June 14, 2007 20:37

428 Cryptococcus Neoformans

➣Urine – consider

➣Sputum – consider

➣Blood – most often positive in AIDS, indicative of extensive infec-

tion

■Serology

➣Cryptococcal antigen (CrAg) – detection of cryptococcal polysac-

charide capsular antigen is clinically very useful

➣False-positive results possible, but usually with titer <1:8

➣CSF and serum testing provides >90% sensitivity for CNS

cryptococcosis; CSF CrAg has better specificity; serum CrAg

specificity for non-CNS infections is lower

➣In HIV patients, a positive serum CrAg always prompts CSF eval-

uation

■Histopathology

➣Organisms easily detected in tissue specimens, especially with

special stains

Imaging

■CT or MRI helpful for defining ventricular system and evaluating

presence of hydrocephalus

■CNS imaging may reveal “cryptococcomas”

■CXR: without AIDS, resembles tumor; AIDS – lymphadenopathy,

pleural effusions, diffuse mixed interstitial and intra-alveolar infil-

trates

differential diagnosis

■Early CNS cryptococcosis may resemble other fungal infections,

tuberculosis, viral meningoencephalitis, or meningeal metastases

■Distinguish cryptococcal masses from other causes of intracranial

lesions: pyogenic, nocardial, aspergillomas, TB, toxo, lymphoma,

neoplasm

■Pulmonary disease hard to distinguish from PCP, tuberculosis,

Histoplasma capsulatum, others – bronchoscopy helps to clarify

management

What to Do First

■Examine CSF, manage high intracranial pressure by serial taps

or consult neurology/neurosurgery for possible shunting, begin

empiric therapy

General Measures

■Begin therapy with Amphotericin B