Silicosis in a marble worker diagnosed by transbronchial lung cryobiopsy| Rassegna di Patologia dell'Apparato Respiratorio

Abstract

In this case report an histopathologic diagnosis of nodular chronic silicosis was achieved in a exposed worker, with suggestive radiological fidings, by performing a transbrochial lung cryobiopsy.

Introduction

Silicosis is a pneumoconiosis due to inhalation of silica (SiO2) over time, mainly observed in occupational settings. It is a fibrotic lung disease that has a long latency period and may clinically present as an acute, accelerated, or chronic form ^1,2.

Case report

A 63-yr-old male, non-smoker marble worker for the past 45 year, presented with a screening Chest X-Ray (CXR) (prescribed by occupational medicine), showing small nodular opacities. Subsequently a Thorax CT scan was carried out (Figs. 1-5): solid and sub-solid nodular lesions were detected, mainly distributed in upper lobes, around 3-6mm in size, some of which were confluent (particularly in the upper segment of the lower right lobe) reaching 10-12 mm diameter; pleural thickening in the upper lobes; and ilo-mediastinal calcified lymphadenopathies were shown.

His comorbidities were: type2 diabetes treated with gliclazide, hypercholesterolemia treated with pravastatin and hyperuricemia treated with allopurinol. He was also on preventive treatment with acetylsalicylic acid (ASA).

In March 2022 he had paucisymptomatic SARS-CoV-2 infection, against which he was vaccinated with 3 doses.

No respiratory symptoms or sign were present. Pulmonary Function Tests were normal (FVC 3.88 L 107%, FEV₁ 3.33L 116%, FEV₁/FVC 82, DL_CO 86%) and Arterial Blood Gas (ABG) test showed a normal gas exchanges (PaO₂ 78.8 mmHg, PaCO₂ 39.4 mmHg, pH 7.43).

Complete laboratory examination revealed slight positivity for anti-ASMA antibodies (1:80) and lactate dehydrogenase (LDH) just above the normal upper limit (226 U/L).

A rigid bronchoscopy was performed with Bronchoalveolar Lavage (BAL) and Transbronchial Cryo Biopsies (TBB cryo) carried out. The cytofluorimetric analysis of BAL showed an increased number of cells with normal cytological profile, except for macrophages with cytoplasmatic brownish granules. Lung biopsies were retrieved from the anterior and the posterior segments of the right lower lobe. Histopathologic aspects were typical silicosis nodules with onion-like collagen deposition and histiocytes containing brownish pigment. Birefringent particles were documented inside the silicotic nodules and in the histiocytic aggregates (Figs. 6, 7).

The final multidisciplinary diagnosis was Classic Nodular Chronic Silicosis and ceasing silica dust exposure was recommended. The patient will be followed with regular imaging, PFT and respiratory examination to state the clinical course of the disease.

Discussion

TBB lung cryobiopsy in interstitial disease has a diagnostic yield that may be close to 90% in very well trained Centers ³. This diagnostic yield is reached with a significantly lower rate of serious side effects compared to surgical lung biopsy ³. In this case report it has been performed to achieve a histopathologic diagnosis of nodular chronic silicosis.

Nowadays, in Italy, there’s a more diffuse knowledge about the prevention in exposed workers, both primary with the use of DPI, water spray and dry air filtering, and secondary with screening CXR and periodical respiratory examination. Therefore the incidence of this pneumoconiosis has significantly reduced over the last decades ^4,5. The case here reported underlines that a chronic exposure in settings not well identified as at risk may be a clinical challenge and that biopsy is still useful to reach e definite diagnosis ⁶.

Figure e tabelle

Figure 1.Upper lobes rounded defined nodules.

Figure 2.Confluent nodules in the right upper lobe.

Figure 3.Nodules and hilo-medistinal adenopathies.

Figure 4.Hilar adenopathies and rounded nodules.

Figure 5.Bases are almost spared.

Figure 6.Transbronchial cryobiopsy sample. Nodules characterized by concentric, acellular, whorled bundles of dense hyalinized collagen fibers. These nodules are located around a small bronchiole or along a lymphatic route (H&E, mid-power).

Figure 7.Transbronchial cryobiopsy sample. A cluster of macrophages around a postcapillary venule containing intracytoplasmic tiny brown particles (H&E, high-power).

Riferimenti bibliografici

1. Greenberg MI, Waksman J, Curtis J. Silicosis: a review. Dis Mon. 2007; 53:394-416. DOI
2. Leung CC, Yu ITS, Chen W. Silicosis. Lancet. 2012; 379:2008-2018. DOI
3. Ravaglia C, Wells AU, Tomassetti S.. Diagnostic yield and risk/benefit analysis of trans-bronchial lung cryobiopsy in diffuse parenchymal lung diseases: a large cohort of 699 patients. BMC Pulm Med. 2019; 19:16. DOI
4. Pesci A, Harari S. Malattie Interstiziali Polmonari. Springer Healthcare Education: Milano; 2018.
5. Li T, Yang X, Xu H, Liu H. Early identification, accurate diagnosis, and treatment of silicosis. Can Respir J. 2022; 2022:3769134. DOI
6. Canessa PA, Torraca A, Lavecchia MA. Pneumoconiosis (silicosis) in the confectionery industry. Sarcoidosis. 1990; 7:75-77.