CYSTIC FORM OF PNEUMOCYSTIS-CARINII PNEUM ONIA

Basic problem and objective: In rare instances Pneumocystis carinii pn eumonia (PCP) can occur in a cystic form, characterized by an acute co urse. The correct diagnosis is often missed. An analysis of a large co hort of patients with PCP was undertaken to determine the incidence an d clinical manifestations of this form of the disease. Patients and me thods: Data on all HIV-positive patients on the hospital registry, hos pitalized with the diagnosis of PCP between January 1988 and July 1996 , were retrospectively analysed. To be included in the study, PCP had to have been confirmed microscopically on bronchial ravage or histolog ically by lung biopsy. The chest radiogram and (if available) computed tomogram of these patients were examined for possible cystic changes, and clinical as well as laboratory findings recorded. Results: Five o f 180 patients with PCP had cystic changes (2.8%). The interval betwee n first symptoms and diagnosis ranged from 30 to 200 days (median: 32 days). All five patients (age: 24-49 years; all males) had a far advan ced immunological disorder (median CD4 count: 10/mu l) and were in sta ge C3 (Centers for Disease Control). Three of the five patients had pr ophylactically inhaled pentamidine (300 mg/month). Bronchial lavage wa s false-negative in three of the five cases. One patient had a spontan eous pneumothorax. Lactate dehydrogenase levels were normal or only sl ightly elevated (207-417 U/l; median 305 U/l). Both the cavities and t hin-walled cysts were demonstrated radiologically, but were more visib le on CT than on the X-ray film. All patients responded well to the me dication with cotrimoxazole, but the prognosis was poor with a surviva l time of only 0.3 to 16 months. Conclusion: PCP should be included in the differential diagnosis when HIV patients have cystic lung changes . Invasive diagnostic methods are often required to avoid wrong diagno sis and superfluous therapeutic interventions.