Lesion size as a prognostic factor in the antifungal treatment of pulmonary cryptococcosis: a retrospective study with chest CT pictorial review of 2-year follow up

Abstract

Background: Pulmonary cryptococcosis (PC) is a fungal infection that can have a variable prognosis depending on several factors. The objective of this study was to analyse the characteristics of pulmonary lesions and identify prognostic factors in patients with PC who were human immunodeficiency virus (HIV) -negative and underwent antifungal treatment.

Methods: The study enrolled patients diagnosed with PC who were negative for HIV. Symptoms, CT characteristics of pulmonary lesions, serum cryptococcal capsular antigen (CrAg) titre, underlying diseases, and duration of antifungal treatment were evaluated over a 2-year follow-up.

Results: A total of 63 patients (40 men and 23 women) with a mean age of 50.4 years were included. Half of the patients (50.8%) were asymptomatic, and the most common symptoms were cough (44.4%), expectoration (27.0%), and fever (17.5%). Pulmonary lesions were mainly present in the peripheral and lower lobes of the lung, with 35 cases classified as nodular-type lesions and 28 cases classified as mass-type lesions. At the first, third, sixth, 12th, and 24th-month follow-ups, the median proportion of residual pulmonary lesions were 59.6%, 29.9%, 12.2%, 9.6%, and 0.0%, respectively. During antifungal treatment, the lesions of 33 patients achieved complete response, while the remaining 30 patients did not. Compared with the non-CR group, the CR group had a lower baseline serum CrAg titre (median, 1:20 vs 1:80, P < 0.01), smaller pulmonary lesion size (median area, 1.6 cm² vs 6.3 cm², P < 0.01), lower Hounsfield-units (HU) radiodensity (median, - 60.0 HU vs - 28.5 HU, P < 0.05), more nodular-type lesions (72.7% vs 36.7%, P < 0.01), and fewer air-bronchogram signs (18.2% vs 43.3%, P < 0.05). Multivariate logistic regression analysis showed that a larger lesion size on chest CT scans was associated with a lower likelihood of achieving complete response [OR: 0.89; 95% CI (0.81-0.97); P < 0.05].

Conclusions: PC was more commonly observed in HIV-negative men, and chest CT scans mostly revealed nodular-type lesions. After antifungal treatment, patients with smaller lesions had a better prognosis.

Keywords: Computed tomography; Cryptococcal capsular antigen; Prognostic factors; Pulmonary cryptococcosis; Pulmonary lesions.