Elsevier

Clinical Imaging

Volume 28, Issue 3, May–June 2004, Pages 191-195
Clinical Imaging

Pulmonary cryptococcosis in immunocompetent patients: HRCT characteristics

https://doi.org/10.1016/S0899-7071(03)00145-1Get rights and content

Abstract

We analyzed the high-resolution CT (HRCT) findings of cryptococcosis in immunocompetent patients. The predominant manifestations were multiple nodules (n=6) and a single nodule (n=7). Regarding the pattern of multiple nodules, two cases of cavities or necrosis, four cases of surrounding centrilobular micronodules and five cases of “acinar” nodules were seen. No “tree-in-bud” appearance was detected. Five of seven cases of a single nodule were classified as polygonal, and two of them were round. Two cases accompanied micronodules and one case cavitation. Although no “tree-in-bud” appearance was observed, pulmonary cryptococcosis mimics tuberculosis.

Introduction

Cryptococcus neoformans is a nonmycelial budding yeast that is isolated from soil contaminated by pigeon and chicken excreta [1]. Cryptococcosis is most widely known for infection of the central nervous system, especially meningitis, but it is introduced basically through inhalation of C. neoformans [2]. Pulmonary infection with C. neoformans can be asymptomatic and subclinical, mild and self-limited or severe and progressive. A study of one large series of patients with normal immunity revealed that only half the patients presented with cough or chest pain. Weight loss and fever were seen in approximately one fourth of the patients. One third of the patients were asymptomatic [3]. Pulmonary cryptococcosis is an infectious disease developed in both immunocompromized hosts, and those without obvious predisposing factors. The radiographic findings in pulmonary cryptococcosis are varied. The immunocompromized hosts demonstrated a wide variety of radiographic abnormalities including single nodules, multiple nodules, single or multiple consolidations. Cavitations, adenopathy and pleural effusions have also been seen [4]. On the other hand, immunocompetent hosts, usually with mild pulmonary symptoms, tended to have a single nodule or multiple nodules [4], which sometimes mimic pulmonary tuberculosis or cancer [5], [6], [7]. The pathogenesis of cryptococcosis is thought to be similar to that of tuberculosis. Inhaled aerosolized organisms are delivered to the lung periphery, and subpleural infection ensues [5]. The purpose of this study was to analyze the findings of high-resolution CT (HRCT) of cryptococcosis in immunocompetent patients to search for the imaging characteristics, especially aspects that can distinguish it from pulmonary tuberculosis.

Section snippets

Materials and methods

The subjects were 13 immunocompetent patients with pulmonary cryptococcosis, who were gathered from multiple institutions from July 1992 to December 1998. The diagnosis of cryptococcosis was confirmed by surgery (n=3), transbronchial biopsy or alveolar lavage (n=5) or serological study for cryptococcal antigen titers (n=5). The 13 patients consisted of six men and seven women with a mean age of 52 years, ranging from 27 to 80 years old. No patient had predisposing factors of immunosuppression.

Results

The main manifestations of cryptococcosis were classified into two patterns: multiple nodules (n=6) and a single nodule (n=7). Consolidation pattern (n=2) accompanied several nodules around the consolidation or other lobes, then it was classified as multiple nodules (Fig. 1). Cavities or necrosis were detected in one case. Regarding the pattern of multiple nodules including cases with consolidation (n=6), two cases of cavities or necrosis, four cases of surrounding centrilobular micronodules

Discussion

McDonell and Hutchins [9] reported four distinct histologic patterns of pulmonary cryptococcosis in their autopsy cases: (1) peripheral pulmonary granuloma, (2) granulomatous pneumonia, (3) intracapillary/interstitial infection and (4) massive pulmonary involvement. Intracapillary/interstitial infection and massive pulmonary involvement are believed to reflect hematogenous dissemination, which occurs in immunocompromized patients. Peripheral pulmonary granuloma and granulomatous pneumonia

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