CASE 13619 Published on 05.05.2016

Classic simple silicosis with bacterial bronchopneumonia

Section

Chest imaging

Case Type

Clinical Cases

Authors

Eleonora Tricarico1, Francesco Tricarico2, Carlo Florio3

(1) University of Bari Medical School,
DIM - Section of Diagnostic Imaging;
Piazza Giulio Cesare 11
70124 Bari, Italy;
Email:eleonoratric@gmail.com
(2) P.O. San Paolo, Dpt of Diagnostic Imaging;
Via Caposcardicchio,
70123, Bari, Italy
(3) C.B.H. Mater Dei,
Dpt of Diagnostic Imaging;
Via Hahnemann,
70124, Bari, Italy
Patient

55 years, male

Categories
Area of Interest Lung ; Imaging Technique CT
Clinical History
A 55-year-old male patient who had worked as a stonemason for 18 years was admitted to the emergency department for acute onset of dyspnoea and fever (39°C). Blood tests revealed an elevation of CPR and leucocytosis. Following the radiographic suspicion of diffuse interstitial lung disease, chest computed tomography (CT) was performed.
Imaging Findings
Chest CT showed diffuse multiple small lung nodules with perilymphatic distribution, predominantly located in the upper lobes, and multiple patchy confluent areas of ground glass and airspace consolidations of the right lower lobe, with associated thickening of the interlobular septa (Fig. 1, 2, 3). Mediastinal window revealed enlarged mediastinal and hilar lymph nodes with eccentric calcifications (Fig. 4). The tuberculin skin test was negative. According with the patient’s occupational anamnesis the diagnostic suspicion of silicosis with associated bronchopneumonia was expressed. Bronchoalveolar lavage (BAL) revealed positive culture for Streptococcus pneumoniae, excluded tuberculosis and showed alveolar macrophages containing dust particles, typical of silicosis. Antibiotic (amoxicillin) therapy was performed, with good clinical outcome. Follow-up chest CT, performed after 20 days, showed a significant reduction of parenchymal consolidations and of thickening of interlobular septa and confirmed the multiple small lung nodules and the enlarged mediastinal and hilar lymph nodes, suggestive of classic simple silicosis (Fig. 5).
Discussion
Silicosis is an occupational respiratory disease caused by inhalation of crystalline silica that determines a fibrotic response in the lung parenchyma. Occupations associated are mining, quarrying, and tunnelling [1]. The risk of developing silicosis is related to the period of exposure to crystalline silica and genetic factors, and removing the source of silica exposure is important to prevent the disease’s progression [1, 2].
Silicosis occurs in three forms, acute, which is progressive and may cause respiratory failure, classic, which could be asymptomatic or manifest with cough and dyspnoea, and accelerated, characterized by a rapid progression [1].
The diagnosis of silicosis is based on occupational anamnesis and radiological findings.
Although chest radiograph is considered the most important diagnostic tool, CT is more sensitive and specific in detection of parenchymal abnormalities [3].
In acute silicosis CT shows perihilar bilateral centrilobular nodular ground-glass opacities and multifocal patchy consolidation with occasional “crazy paving” pattern [4].
Classic silicosis is classified on the basis of radiological findings as simple or complicated.
Simple silicosis is characterized on CT by multiple small nodules, sometimes calcified, with perilymphatic distribution and main involvement of upper lobes. Hilar and mediastinal lymph node enlargement, usually with peripheral calcifications (“eggshell pattern”) is typical.
Complicated silicosis presents focal soft-tissue masses, with irregular margins, indicative of fibrosis, surrounded by areas of emphysematous changes. Because of the mass-like appearance, a problem of differential diagnosis with lung cancer may occur; the imaging features suggesting lung cancer are unilaterality of the mass, absence of calcification and rapid growth rate, while complicated silicosis reveals bilateral and symmetrical masses, sometimes with calcifications, and presents slow progression [5].
Accelerated silicosis shows radiological characteristics of both acute and classic silicosis [4].
Patients with silicosis have an increased risk of developing pulmonary tuberculosis and other mycobacteria-related diseases, maybe because of modified immune response determined by silica. The diagnosis of superimposed tuberculosis could be difficult in the early stage of the infection, because of its radiological pattern very similar to silicosis. In case of clinical suspicion in a patient with known silicosis, a sputum culture and chest radiograph must be performed, and if both investigations don’t rule out the infection, bronchoscopy with BAL and eventual biopsy are necessary. CT may be useful in the diagnosis of silicotuberculosis, showing centrilobular nodules with a "tree in bud" pattern and a rapid progression of parenchymal abnormalities [4, 6].
Differential Diagnosis List
Classic simple silicosis with bacterial bronchopneumonia
Sarcoidosis
Tuberculosis
Final Diagnosis
Classic simple silicosis with bacterial bronchopneumonia
Case information
URL: https://www.eurorad.org/case/13619
DOI: 10.1594/EURORAD/CASE.13619
ISSN: 1563-4086
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