Silicosis with Bilateral Spontaneous Pneumothorax in Rajasthan.

BACKGROUND AND AIMS: Silicosis is an occupational lung disease caused by inhalation of crystalline silica. People working in occupations like sandblasting, surface drilling, tunnelling, silica flour milling, ceramic making are predisposed to develop silicosis. Unilateral spontaneous pneumothorax is a pleural complication that can develop in such cases. Our aim is to see the prevalence of bilateral pneumothorax in silicosis in Rajasthan and associated predisposing factors.
METHODS: Fifty patients of silicosis prospectively reviewed by historical, clinical evaluation, and radiological evidence with increased dyspnea and chest pain in 1 year were included in the study. In all patients, chest X-ray was done immediately. Sputum for acid fast bacilli was done in all cases.
RESULTS: Cough and shortness of breath were most common symptoms and present in all cases. All cases were smokers. Chest radiograph revealed reticulonodular density with B/L pneumothorax in all patients. Tube thoracostomy was done in all cases except one in which conservative management was done.
CONCLUSIONS: Cases with silicosis can develop complications like tuberculosis, lung cancer, progressive massive fibrosis, cor pulmonale, broncholithiasis, or tracheobronchial compression by lymph nodes. Pleural involvement in silicosis is rare. Spontaneous pneumothorax is a pleural complication that can develop in such cases. Usually in silicosis pneumothorax is unilateral. We report here an original article with silicosis who presented with bilateral spontaneous pneumothoraxes occurring simultaneously. The rarity of its clinical presentation in the form of bilateral simultaneous spontaneous pneumothorax combined with the typical clinical and radiological features of silicosis will make us to report this article. Copyright:

INTRODUCTION

Silicosis is an occupational lung disease caused by the inhalation of crystalline silica. Crystalline silica is classified as a group 1 substance by the International Agency for Research on Cancer.[1] It usually presents after decades of exposure as a slowly progressing nodular fibrosing pneumoconiosis.[2] Silicosis is a worldwide problem that has been noted from various countries such as China, Brazil, UK, USA, Iran, and India.[34] Workers in certain occupations are exposed to high concentrations of silica due to its fibrogenicity which causes radiological and pathological abnormalities in the lungs. Exposure to large amounts of free silica can go unnoticed because silica is odorless, non-irritant, and does not cause any immediate health effect. Crystalline forms of silica are more fibrogenic than the amorphous forms, highlighting the importance of the physical form in pathogenesis. The disease has a long latency period and may clinically present as an acute, accelerated, or chronic disease. Although silicosis is a preventable disease, it continues to be an important health problem, especially in low-income communities.

Pleural involvement, including pleural effusion, pleural thickening, or pneumothorax is rarely seen in silico sis.

Pneumothorax is one of the most important complications of silicosis associated with pleura. It is usually seen unilaterally during the course of chronic silicosis and may sometimes be fatal. However, pneumothorax is uncommon in acute and accelerated forms of silicosis.

Involvement of pleura in silico sis is rare and secondary spontaneous pneumothorax (SSP) is the only recognized pleural complication of silicosis. SSP occurs late in the course of disease and may prove a fatal complication along with underlying grossly compromised pulmonary function. SSP. The incidence of SSP in silico sis as such is not known. SSP is usually unilateral, but sometimes may present as bilateral pneumothorax which is rare presentation.[23] Authors report a case series of bilateral SSP in a patient silicosis. In this study, we report 20 bilateral secondary spontaneous pneumothorax case complications of silicosis associated with pleura.

METHOD

We prospectively reviewed the clinical and imaging records of 20 patients of silicosis with B/L pneumothorax. Imaging studies available included chest radiograph. Chest radiograph revealed B/L pneumothorax in all patients. According to smoking history pack years is calculated. Sputum for acid fast bacilli is done by Z-N staining method in all cases.

RESULT

The mean duration of exposure to silica particles was 13.7 year. Most of the patient belonged to economically productive age group (20--45 years) and one patient above 60 years. In the diagnosis, silicosis confirmed with combinations of typical occupational, historical, clinical, and radiological evaluations were used in the diagnosis.[4] All of the patients had various degrees of dyspnoea (SOB) and bilateral (B/L) chest pain.

All patients had cough at presentation, out which 11 (55%) patients had dry cough and nine (45%) patient with productive coughs, eight (40%) patients experienced loss of appetite. Fifteen (75%) patients had a history of smoking. Chest X-rays of all patients revealed bilateral, widespread, reticulonodular, and nodular appearances. Twelve patients had work on crusher machine and eight patients as manual stone cutter. Pneumothorax was located bilaterally in all cases. One patient put on conservative treatment (refused consent for ICDT) while unilateral tube thoracstomy was done most of patients [Figures 1–4] and bilateral tube thoracostomy done in six patients9 [Figure 5]. Table 1 summarizes the age, duration of exposure, localization of pneumothorax, smoking habits, and type of stone worker, nature of stone, and treatment of the cases.

Figure 1

Chest radiography - Bilateral pneumothorax (case no 12)

Figure 4

Chest radiography - Bilateral pneumothorax (case no 13)

Figure 5

Chest radiography - Bilateral pneumothorax with right side ICDT (case no 14)

Table 1

Characteristics of the patients

Case	Age (years)	Chief complain	Exposure time (years)	Types of works	Types of stone dusts	Sputum AFB	Smoker (pack years)	Treatment given
1	30	SOB, b/L chest pain, dry cough	16	Mine Crusher	Dholpur	Neg	16	Rt ICDT
2	26	SOB, b/l chest pain, dry cough	5	Crusher	Dholpur	Neg	Non smoker	Lt ICDT
3	27	SOB, b/l chest pain, productive cough, fever. LOA, LOW	13	Crush machine	Karoli	Pos	1	Rt ICDT
4	35	SOB, b/l chest pain, dry cough, LOA, LOW	9	Crusher machine	Dholpur	Neg	5	B/l ICDT
5	30	SOB, b/l chest pain, productive cough, fever. LOA,	10	Stone cutter	Dholpur	Pos	5	Lt ICDT
6	65	SOB, b/l chest pain, dry cough, fever. LOA, LOW	20	Crush machine	Karoli	Pos	10	Conservative
7	45	SOB, b/l chest pain, dry cough	13	Stone cutter	Jodhpur	Neg	5	Rt ICDT
8	53	SOB, b/l chest pain, dry cough	24	Stone cutter	Karoli	Neg	30	Lt ICDT
9	42	SOB, b/l chest pain, dry cough, fever	18	Crusher machine	Dholpur	Neg	20	B/l ICDT
10	38	SOB, b/l chest pain, productive cough, fever.	15	Stone cutter	Jodhpur	Neg	Non smoker	Rt ICDT
11	45	SOB, b/l chest pain, productive cough, fever. LOA, LOW	10	Mine Crusher	Dholpur	Neg	11	b/l ICDT
12	40	SOB, b/l chest pain, dry cough	11	Stone cutter	Karoli	Positive	Non-smoker	Left ICDT
13	37	SOB, b/l chest pain, productive cough, fever.	12	Crusher machine	Jodhpur	Neg	20	B/L ICDT
14	28	SOB, B/L chest pain, cough with expectotarion, fever	8	Stone crushing	Dholpur	Positive	30	RT ICDT
15	30	SOB, b/l chest pain, productive cough, fever	13	Mine crusher	Jodhpur	Neg	Nonsmoker	Left ICDT
16	40	b/l chest, SOB, loss of appetite	10	Stone cutter	Dholpur	Neg	5	RT ICDT
17	45	SOB, b/l chest pain, dry cough	15	Crusher	Jodhpur	Neg	12	B/L ICDT
18	42	SOB, b/l chest pain, productive cough, fever. LOA, LOW	14	Mine crusher	Karoli	Positive	16	Left ICDT
19	29	SOB, b/l chest pain, dry cough, LOA, LOW	20	Stone cutter	Jodhpur	Neg	Non-smoker	B/L ICDT
20	45	SOB, b/l chest pain, dry cough	18	MINE cutter	Karoli	Neg	20	RT ICDT

B/l pneumothorax (case no 8)

Chest radiography - Bilateral pneumothorax (case no 5)

The average duration of hospitalization was 11 days (range 6--17 days). Sputum examination and cultures for Mycobacterium tuberculosis (M. tuberculosis) were negative except in six. On follow-up, none of the patients had complete expansion of lung on follow-up. Most of them refused for an operative intervention. One of the cases had died in hospital and another died a month after discharge from hospital. Others were extubated but with some degree of residual pneumothorax.

DISCUSSION

Silicosis commonly occurs in workers involved in quarrying, mining, sandblasting, tunnelling, foundry work, and ceramics industry.[5] Respirable crystalline silica is <10 micron in diameter and it can reach to the basal segments of the lung. It accumulates and induces silicosis although the exposure is low.[6]

There are studies, where, in advanced silicosis secondary spontaneous pneumothorax is shown to be associated with the presence of bullae.[3] Due to direct toxic injury by silica, products of inflammatory response affect the elastic fibere of the alveolar wall leading to formation of bleb.[7] Massive fibrosis of lung results in a stiff nondistensible lung with an increased elastic recoil. Secondary spontaneous pneumothorax may be due to the rupture of the bullae and can be facilitated by the increased elastic recoil of lung parenchyma.[3] Some congenital alveolar defects and dysfunction of type II cells have also been considered to lead to development of pneumothorax.[7]

Tuberculosis may contribute to the development of massive fibrosis in silico sis patients. This condition can be seen in 20--25% of silicosis patients during their lifetimes. Other complications are esophageal compression, and left recurrent laryngeal nerve palsy along with chronic cor pulmonale, pneumothorax, and bronchial tree perforation by calcified lymph nodes.

It is believed that crystalline silica is most pathogenic when it is smaller than 1 cm in diameter.[8] Direct tissue damage by silica particles causes an imbalance between the inflammatory response products. In turn, this has an effect on the elasticity of the alveolar walls, formation of alveolar blebs in the upper lobes, and some congenital defects. Thus, pneumothorax development can be seen with the dysfunction of type 2 alveolar cells. Pneumothorax is seen in the course of silicosis, but when it is present, it is usually unilateral. It commonly emerges during chronic silicosis and is accompanied by progressive massive fibrosis. Sporadic spontaneous pneumothorax cases have been reported in accelerated silicosis.[8]

The predictive factors for development of SSP in patients with silicosis have not been extensively described in literature. In one study a strong association was found between the occurrence of SSP and presence of bullae. Silicosis is also associated with emphysematous changes in lungs, independent of smoking. In advanced silicosis coalescence of perinodular emphysematous regions may lead to formation of macroscopic blebs which rupture causing pneumothorax.[9]

First thing is that there are chemical and physical properties behind pneumothorax in silico sis patients in Dholpur, Karoli, and Jodhpur. Stone in these areas are basically sand stone which is defined as stone made up of grains of quartz and other minerals of fairly uniform size and often smooth and rounded. Quartz, cristobalite, and some forms of tridymite are inherently piezoelectric. Piezoelectricity is a property that produces opposite electric charges on opposite sides of the physical structure when pressure is applied directly to the crystal. This phenomenon occurs in crystalline silica because the chemical structure does not have a center, reflecting an inversion symmetry. In addition, the opposite sides of these crystals have dissimilar surfaces and carry opposite electrical charges. It is theorized that these piezoelectric characteristics may play a role in the pathophysiology of silica-related illness by the generation of oxygen-free radicals produced on the cleaved surfaces of silica molecules and as a result of silica-damaged alveolar macrophages.[210] Table 2 shows chemical composition of different sand stone.

Table 2

Chemical composition of different sand stone[

Percentage	Jodhpur	Karoli	Dholpur
Sio2	96.60	96.20	98.20
Fe2O3	1.20	0.80	0.84
Al2O3	1.00	1.20	0.32
CaO	0.28	0.40	0.28
MgO	0.20	0.20	Nil
L.O.I	0.50	0.60	0.20

Table 2 shows that Dholpur stone contain highest percentage of silica followed by Jodhpur and Karoli stone. In our study, eight cases engaged with Jodhpur stone, six patients Karoli, and six with Dholpur stone. So density of Jodhpur stone is more than Karoli and Dholpur, so probably it could be the more chances to do pneumothorax in that area, proving the second hypothesis of this study [Table 3].[11]

Table 3

Technical information of sandstone

Properties	Jodhpur	Karoli	Dholpur
Density (Kg/m3)	2.42	2.38	2.40
Water Absorption (%)	1.25	1.20	1.20
Modulus of Rupture (Kg/cm3	220	210	208
Compressive Strength (kg/cm3)	390	358	460

Third thing in our study showed an increased prevalence of secondary pneumothorax in silico sis with smoker patients. It was also already proved by the study done by Bense et al.[11]

Fourth thing SBSP is an extremely rare occurrence. It tends to affect males more often than females, usually those in their late 20s as in our case all cases were male.[12]

As in other cases of secondary spontaneous pneumothorax, pneumothorax induced by silicosis requires an aggressive approach to treatment. However, there is no accepted consensus for the treatment. In these patients, tube thoracostomy should be applied in all cases, even in the first episodes, due to the presence of excessive pulmonary inflammation and fibrosis and the high tendency for recurrence.

CONCLUSION

This study shows that pneumothorax due to silicosis can cause serious morbidity and mortality. When chest pain and dyspnoea occur suddenly in silico sis patients, diagnosis must be made quickly, and pneumothorax should be kept in mind.

Our study showed an increased prevalence of secondary pneumothorax in silico sis patients. Smoking may be a risk factor for development of pneumothorax. Pneumothorax in silico sis patients can cause serious morbidity and mortality. Although the occurrence of SSP is rare in silico sis, but whenever chest pain and dyspnoea occur suddenly or has increased recently in a silicosis patient, the patient should be promptly investigated and pneumothorax should be kept in mind.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.