Cryptococcosis

Pathophysiology

1) caused by infection with the yeast-like fungus Cryptococcus neoformans 2) two distinct subtypes 3) most commonly seen in USA as late complication of AIDS 4) primarily causes meningoencephalitis and lung disease

Signs and Symptoms

1) fever 2) headache 3) nausea 4) ataxia 5) papilledema 6) cranial nerve palsies 7) irritability 8) confusion 9) visual problems 10) chest pain 11) cough 12) skin lesions that slowly expand and ulcerate

Characteristic Test Findings

Laboratory – 1) positive capsular antigen by laxtex agglutination 2) best diagnostic test is lumbar puncture with India ink smear of centrigued CSF 3) decreased glucose in CSF 4) increased protein in CSF Radiology – 5) one or more well-circumscribed dense infiltrates on chest radiography

Histology/Gross Pathology

1) capsular serotypes – A, B, C, and D 2) organisms are encapsulated, round yeasts that reproduce by budding 3) best cultured on Sabourad’s medium or Niger seed agar 4) localize in brain in basal ganglia, meninges, and perivascular gray matter 5) causes an intense granulomatous response around lung lesions

Associated Conditions

1) increased incidence with – HIV, immunosuppression after solid organ transplantation, glucocorticoid therapy, sarcoidosis 2) unusual sequelae – hepatitis, renal abscess, prostatitis, pericarditis, endophthalmitis

Inheritance/Epidemiology

1) transmission is most likely through inhalation 2) for non-high risk patients exposure is through contact with infected pigeon droppings and from around base of eucalyptus trees in Australia

Treatment

1) in AIDS – IV amphotericin B with flucystosine for at least 2 weeks or until symptoms resolved and then fluconazole chronically 2) nonimmunosuppressed patient – IV amphotericin B with fluconazole until cultures from previously postive sources are repeatedly negative

Tips for USMLE

1) if a 43-year old AIDS patient develops confusion, nausea, staggering gait, and headache with a lumbar puncture that shows organisms seen on India ink stain, think cryptococcosis 2) if pigeon droppings are mentioned (pigeon droppings can carry other diseases), consider cryptococcosis