CONTENTS
- Asbestos
- Silicosis
- Coal workers pneumoconiosis
- Berylliosis
- Talcosis
- Silicone embolism syndrome
- Questions & discussion
abbreviations used in the pulmonary section: 8
- ABPA: Allergic bronchopulmonary aspergillosis 📖
- AE-ILD: Acute exacerbation of ILD 📖
- AEP: Acute eosinophilic pneumonia 📖
- AFB: Acid-fast bacilli
- AIP: Acute interstitial pneumonia (Hamman-Rich syndrome) 📖
- ANA: Antinuclear antibody 📖
- ANCA: Antineutrophil cytoplasmic antibodies 📖
- ARDS: Acute respiratory distress syndrome 📖
- ASS: Antisynthetase syndrome 📖
- BAL: Bronchoalveolar lavage 📖
- BiPAP: Bilevel positive airway pressure 📖
- CEP: Chronic eosinophilic pneumonia 📖
- CF: Cystic fibrosis 📖
- COP: Cryptogenic organizing pneumonia 📖
- CPAP: Continuous positive airway pressure 📖
- CPFE: Combined pulmonary fibrosis and emphysema 📖
- CTD-ILD: Connective tissue disease associated interstitial lung disease 📖
- CTEPH: Chronic thromboembolic pulmonary hypertension 📖
- DAD: Diffuse alveolar damage 📖
- DAH: Diffuse alveolar hemorrhage 📖
- DIP: Desquamative interstitial pneumonia 📖
- DLCO: Diffusing capacity for carbon monoxide 📖
- DRESS: Drug reaction with eosinophilia and systemic symptoms 📖
- EGPA: Eosinophilic granulomatosis with polyangiitis 📖
- FEV1: Forced expiratory volume in 1 second 📖
- FVC: Forced vital capacity 📖
- GGO: Ground-glass opacity 📖
- GLILD: Granulomatous and lymphocytic interstitial lung disease 📖
- HFNC: High flow nasal cannula 📖
- HP: Hypersensitivity pneumonitis 📖
- IPAF: Interstitial pneumonia with autoimmune features 📖
- IPF: Idiopathic pulmonary fibrosis 📖
- IVIG: Intravenous immunoglobulin 📖
- LAM: Lymphangioleiomyomatosis 📖
- LIP: Lymphocytic interstitial pneumonia 📖
- MAC: Mycobacterium avium complex 📖
- MCTD: Mixed connective tissue disease 📖
- NIV: Noninvasive ventilation (including CPAP or BiPAP) 📖
- NSIP: Nonspecific interstitial pneumonia 📖
- NTM: Non-tuberculous mycobacteria 📖
- OHS: Obesity hypoventilation syndrome 📖
- OP: Organizing pneumonia 📖
- OSA: Obstructive sleep apnea 📖
- PAP: Pulmonary alveolar proteinosis 📖
- PE: Pulmonary embolism 📖
- PFT: Pulmonary function test 📖
- PLCH: Pulmonary Langerhans cell histiocytosis 📖
- PPFE: Pleuroparenchymal fibroelastosis 📖
- PPF: Progressive pulmonary fibrosis 📖
- PVOD/PCH Pulmonary veno-occlusive disease/pulmonary capillary hemangiomatosis 📖
- RB-ILD: Respiratory bronchiolitis-associated interstitial lung disease 📖
- RP-ILD: Rapidly progressive interstitial lung disease 📖
- TNF: Tumor necrosis factor
- UIP: Usual interstitial pneumonia 📖
epidemiology: risk for contact with asbestos
- Mining, milling, or manufacture of asbestos.
- Construction workers (including plumbers, electricians, and pipe/boiler fitters).
- Car mechanics (especially with exposure to brake linings).
- Manufacturers and installers of floor tiling, insulation, fireproof textiles, and sheet metal.
- Demolition workers. (Shah 2019)
basics
- This is a relatively close mimic of IPF (idiopathic pulmonary fibrosis).
- Disease may continue to progress, even in the absence of ongoing asbestos exposure.
epidemiology
- Asbestosis usually develops after a latency of ~20-40 years following exposure. However, earlier cases may occur following unusually severe exposure. (Shepard 2019)
clinical presentation
- The primary symptom is insidious onset of dyspnea.
- Patients may have a nonproductive cough.
- Clubbing may be seen in about a third of patients.
- In advanced stages, features of cor pulmonale emerge.
radiology
- Distribution: Tends to be more prominent in lower lobes and subpleural areas. (Murray 2022)
- Key findings on CT scan:
- Curvilinear subpleural lines (may run parallel to the pleura).
- Parenchymal bands 2-5 cm long may course into the lung from the pleural surface. These bands are related to pleural thickening, fibrosis, and round atelectasis. (Shepard 2019)
- Reticulation (thickened interlobular septa) is usually mild.
- Honeycombing occurs late in the disease process (this may appear identical to IPF, with peripheral and basal predominance).
- Other findings:
- Centrilobular nodular opacities may occur (peribronchiolar fibrosis).
- Pleural plaques may be seen in ~85% of patients; this provides a clue to the diagnosis.
- Diffuse pleural thickening.
treatment
- There is no specific therapy, treatment is supportive.
- Management strategies for IPF may provide useful concepts for patient care: 📖
prognosis
- Asbestosis is usually slowly progressive, leading to respiratory failure.
- Risk factors for progression:
- Greater cumulative asbestos exposure.
- Crocidolite (blue asbestos) exposure.
epidemiology
- Plaques are usually identified >20 years after asbestos exposure.
- These are the most common manifestation of asbestos exposure, seen in:
- ~40% of occupationally exposed workers.
- ~4% of non-occupationally exposed people.
clinical significance
- Pleural plaques predominantly involve the parietal pleura.
- Plaques do not generally cause symptoms, substantially affect pulmonary function tests, or alter the pulmonary physical examination.
- Pleural plaques are specific signs of asbestos exposure. However, they don't independently correlate with the risk of mesothelioma or lung cancer.
- No specific therapy is indicated.
radiology of asbestos pleural plaques
distribution:
- Plaques should be bilateral (be cautious about making this diagnosis if only one pleural cavity is involved).
- Plaques tend to involve:
- (1) Diaphragm – diaphragmatic pleural plaques are nearly pathognomonic for asbestos exposure. (Shepard 2019)
- (2) Anterolateral chest wall.
- (3) Posteromedial chest wall (paraspinous area).
- Plaques may enter lobar fissures and even invade the mediastinum. (Fishman 2023)
- Plaques tend to spare the upper zones and costophrenic angles.
general properties
- Calcification occurs in ~10-15% of plaques, most often over the diaphragm and lateral chest wall.
chest radiograph
- In tangent on chest radiograph, plaques may appear as localized nodular or bandlike areas of pleural thickening. (Shepard 2019)
CT scan
- CT scanning is more sensitive than chest radiograph.
- CT scan may show characteristic “hairs” in the lung parenchyma overlying the pleural plaques, which represent a fibrous reaction to asbestos fibers. (Shah 2019)
basics
- Asbestos is a common cause of diffuse pleural thickening (diffuse, bilateral pleural fibrosis). Although this is “diffuse,” it doesn't generally involve the entire visceral pleura (but rather often causes a continuous sheet that is 5-10 cm in length). (Fishman 2023)
- Unlike pleural plaques, diffuse pleural fibrosis involves the visceral pleura and impairs pulmonary function. (Shepard 2019) Pathophysiologically, diffuse pleural thickening could be regarded as an extension of fibrotic parenchymal involvement with asbestos. (Folch 2023)
epidemiology of diffuse pleural thickening
- This occurs in ~5% of people exposed to asbestos.
- Disease develops after a latency of ~10-40 years following asbestos exposure. (Shepard 2019)
- ~40% of cases are preceded by BAPE (benign asbestos pleural effusion). (Murray 2022)
clinical presentation
- Dyspnea on exertion is the most common symptom (>95%). Other symptoms may include chest pain (>50%) and chronic dry cough. (Fishman 2023; Folch 2023)
- Restrictive physiology may eventually cause chronic hypercapnic respiratory failure with cor pulmonale.
- Diffuse pleural thickening is usually slowly progressive. (Murray 2022)
radiology
- Asbestos pleural fibrosis may cause restrictive physiology without substantial radiological abnormality. However, fibrosis may also cause radiographically visible thickening of the visceral pleura.
- Chest radiograph may show pleural thickening and blunting of the costophrenic angles that mimics pleural effusions (the costophrenic angle is involved in ~90% of patients).
- CT scan:
- The hallmark finding of diffuse pleural thickening is a continuous sheet of pleural thickening >3 mm thick, >5 cm wide, and >8 cm in craniocaudal extent. (Shepard 2019; Folch 2023)
- Coexisting parenchymal asbestosis may be seen.
- Other pleural abnormalities:
- (1) Highly negative pleural pressures may cause the development of localized, transudative effusion in areas where the visceral and parietal pleura aren't fused.
- (2) Pleural fibrosis may cause areas of round atelectasis.
evaluation
- If there is substantial pleural thickening, biopsy may be needed to exclude malignancy. However, PET scanning may also be used to help exclude malignancy.
differential diagnosis
- Other causes of diffuse pleural thickening: 📖
treatment
- Thoracotomy with pleurectomy may be performed. Unfortunately, this is a difficult procedure which may not completely resolve the lung restriction.
- Long-term nocturnal noninvasive ventilatory support may be useful for patients with hypercapnia.
There are roughly three forms of silicosis: acute silicosis, chronic nodular silicosis, and silicosis-induced progressive massive fibrosis.
epidemiology of silicosis
sources of silica exposure
- Silicosis is the most common chronic occupational lung disease worldwide. The risk is higher in underdeveloped countries that lack adequate worker protections. (28961033) Silica is found in sand, quartz, many other types of rocks, and some some metallic ores.
- Sources of silica exposure vary widely:
- Cutting, polishing, and carving of real or artificial stone.
- Mining, quarry working, or fracking.
- Ceramics, pottery, and glass manufacture. (Shah 2019)
- Sandblasting (may also be used in the manufacture of various items, such as clothing).
- Packing of silica flour (used in cements).
- Cement workers.
- Manufacture of abrasive soaps containing bits of silica.
- Road work involving “cut and repair.”
- Dental workers. (28797400)
- Usually at least five years of exposure is required to cause disease, unless exposure is extremely intense.
- Social history should evaluate for prior exposures, which are probably more relevant than current.
- Progression of disease may continue after removal from exposure.
diseases associated with silicosis
- Rheumatologic disorders:
- Infection:
- Tuberculosis.
- Nocardia.
- COPD, lung cancer.
epidemiology of acute silicosis
- Extremely intense exposure causes silicosis to develop within a few years (possibly even within a few weeks of exposure). (Shah 2019)
- Causes:
- Primarily described among sandblasters. (Shepard 2019)
- Other causes include tunnel boring, silica mining, or silica flour milling. (34099157)
epidemiology of chronic, nodular silicosis
- Chronic (>20 years), low-level exposure causes nodular lung disease that is asymptomatic.
- (“Accelerated silicosis” is a hybrid of acute and chronic silicosis, potentially occurring among patients with intermediate intensities of exposure.)
epidemiology of silicosis-induced chronic, progressive massive fibrosis
- Chronic (>20 years), low-level exposure causes nodular lung disease that is gradually progressive and symptomatic.
clinical presentation of silicosis
acute silicosis
- Presents with dyspnea, cough, and weight loss.
- Often progresses to respiratory failure and mortality within <2 years (even despite cessation of exposure).
chronic, simple nodular silicosis
- Patients are generally asymptomatic.
- Pulmonary function tests are usually normal (although some mixture of restriction and obstruction can occur).
silicosis-induced progressive massive fibrosis
- Slowly progressive dyspnea occurs.
- Cough and sputum production may occur.
- Patients may develop pulmonary hypertension.
radiology of silicosis
acute silicosis
- Causes a diffuse alveolar pattern similar to pulmonary alveolar proteinosis (PAP). (Indeed, silica exposure may technically cause a secondary form of pulmonary alveolar proteinosis.)
- Ground-glass opacification with septal thickening generates a crazy-paving pattern.
- Perihilar distribution with air bronchograms may occur.
- Centrilobular nodules may occur. (Murray 2022)
chronic, simple nodular silicosis
- (1) Multiple nodules:
- Lesions are usually ~2-5 mm (but may range up to 1 cm).
- Compared to coal workers pneumoconiosis, nodules are better defined.
- Nodules typically have a perilymphatic distribution.
- Nodules may occasionally calcify.
- (2) Hilar lymphadenopathy is typically also seen:
- Eggshell calcification is infrequent, but if seen this is nearly pathognomonic. 📖
- The combination of hilar lymphadenopathy and some perilymphatic nodules can mimic sarcoidosis.
silicosis-induced progressive massive fibrosis
- Overall: All of the features of chronic, simple nodular silicosis described above may be seen. In addition, fibrotic masses are seen.
- Key features of progressive massive fibrosis:
- Large, 1-10 cm irregularly shaped masses.
- These typically develop at the lung periphery and migrate towards the hilum.
- Usually bilateral, but asymmetric.
- Almost always restricted to the upper half of the lungs.
- Other attributes:
- May contain small calcifications.
- Over time, these lesions tend to contract. This may cause traction-related emphysema and bullae around the edge of the masses (paracicatricial emphysema).
- Cavitation can rarely occur due to ischemic necrosis. (Shepard 2019) However, if encountered, this should raise a concern for superimposed tuberculosis or malignancy. Any rapid changes suggest superimposed infection.
- Differential diagnosis may include:
- Bronchogenic carcinoma.
- Lymphoma.
- Sarcoidosis.
- Tuberculosis and atypical mycobacterial infection are associated with silicosis. In some patients, this may be difficult to differentiate from progressive massive fibrosis.
- Histoplasmosis.
- Coal workers pneumoconiosis.
diagnosis of silicosis
general principles of diagnosis
- Diagnosis requires three general components: (30131836)
- (1) Exposure history to silica.
- (2) Radiology consistent with silicosis.
- (3) Reasonable exclusion of alternative diagnoses.
- Diagnosis is largely based on radiology combined with an exposure history.
need for tissue diagnosis?
- Diagnostic biopsy is rarely needed. (28961033)
- In atypical cases, bronchoscopy may be useful to:
- Exclude infection (e.g., tuberculosis).
- Demonstrate the presence of silica in lavage fluid (birefringent material seen under polarized microscopy within macrophages). (36865940)
- Treatment of silicosis generally involves observation, so when in doubt it may be reasonable to simply observe with serial imaging. This is unlike diseases like sarcoidosis, where there is more urgency to define the precise diagnosis prior to initiation of steroid.
treatment of silicosis
- Any additional exposure should be avoided.
- Basic supportive measures for lung disease:
- Smoking cessation.
- Recommended vaccinations.
- There should be vigilance for superinfection:
- Tuberculosis rates are increased ~30-fold in the context of silicosis. (28961033)
- Acute silicosis may increase the risk of Nocardia infection. (Fishman 2023)
- Acute silicosis complicated by pulmonary alveolar proteinosis (“silicoproteinosis”) may be treated with whole-lung lavage. (33304397) For further discussion of this, see the section on pulmonary alveolar proteinosis. 📖
- Progressive fibrotic disease may be treated with an antifibrotic agent (e.g., nintedanib). (36865940)
- Lung transplantation may be an option for patients with advanced silicosis.
basics
- Coal workers pneumoconiosis (aka black lung disease) is similar to silicosis, in that it may exist in two forms (simple nodular disease, progressive massive fibrosis).
epidemiology
- May affect ~10% of coal miners.
- Typically results from >10 years exposure to coal mining.
symptoms
- Simple coal workers pneumoconiosis:
- Generally asymptomatic.
- Cough and sputum production may occur.
- CWP-induced progressive massive fibrosis:
- Progressive dyspnea is the primary symptom.
- Melanoptysis (expectoration of black sputum) may occur if a lesion undergoes liquefaction with cavitation. (Fishman 2023)
radiology
- Simple coal workers pneumoconiosis:
- Rounded, small nodular opacities.
- May produce a miliary pattern (with a differential diagnosis including tuberculosis or histoplasmosis).
- May tend to occur in the posterior aspect of the upper lobes.
- CWP-induced progressive massive fibrosis:
- Nodules conglomerate into masses >1 cm.
- Usually located in the upper lung zones.
- If cavitation occurs, this raises the possibility of superimposed fungal or mycobacterial infection.
- Dust-related diffuse fibrosis (DDF):
- Less common form of lung disease.
- Radiologically, this can mimic idiopathic pulmonary fibrosis (IPF). However, a background of nodular opacities may be a useful clue towards the actual etiology.
management
- Further coal exposure should be avoided.
- Tobacco cessation is critical (since this is additive with coal exposure, in terms of impairment of lung function).
- Care is supportive.
basics
- Berylliosis is very similar to sarcoidosis (histologically and radiographically), although it rarely involves extrathoracic organs.
- Unless suspected, most cases of berylliosis will be misdiagnosed as sarcoidosis (imaging and histopathology are largely identical).
epidemiology
- Berylliosis may occur in ~2% of people exposed to beryllium:
- ~5% of exposed workers will develop sensitivity to beryllium.
- ~50% of sensitized workers will develop clinical disease.
- Following low-level exposure, there may be a latency period of months to a decade prior to developing berylliosis.
- Sources of beryllium exposure include work with:
- Electronics.
- Jewelry, ceramics.
- Sporting goods (e.g., used in golf clubs and bicycle frames).
- Dentistry.
- Aerospace, nuclear weapons. (Murray 2022)
symptoms
- Dyspnea is the most common presenting symptom.
- Cough and substernal chest pain may also occur.
- Systemic symptoms may include fatigue, weight loss, and arthralgias.
- Advanced disease may be accompanied by:
- Clubbing.
- Cor pulmonale (with peripheral edema and systemic congestion).
- Other findings:
- Rare patients may present with signs and symptoms mimicking asthma.
- ~20% of patients develop small granulomatous nodules on the arms, hands, and chest. (Fishman 2023)
laboratory studies
- Labs may resemble those seen in sarcoidosis (e.g., elevated ACE level, hypercalcemia).
- Blood Beryllium Lymphocyte Proliferation Test (BeLPT) establishes sensitivity to beryllium and prior exposure (without proving the presence of berylliosis). Some patients may have a positive BeLPT in bronchoalveolar lavage fluid, despite a negative serum test. (Fishman 2023)
imaging
- CT findings are similar to sarcoidosis. Common findings include: (Shah 2019)
- Small nodules with a peribronchovascular distribution (most common finding).
- Mediastinal and hilar lymphadenopathy (seen in about a third of patients, usually mild).
- Eventually, upper lobe honeycombing and calcifications can occur.
sorting out berylliosis versus sarcoidosis
- (1) Extrapulmonary involvement is generally rare in berylliosis:
- Features suggestive of sarcoidosis:
- Cardiac involvement.
- Uveitis, parotid involvement.
- Neurologic involvement.
- Erythema nodosum.
- However, dermatitis favors berylliosis.
- Features suggestive of sarcoidosis:
- (2) Radiology is usually very similar, but some features may be suggestive:
- Hilar lymphadenopathy without parenchymal infiltrates favors sarcoidosis.
- Ground-glass appearance on CT scan favors berylliosis.
- (3) Improvement after short-term steroid therapy may favor sarcoidosis.
- (4) Features favoring berylliosis:
- Positive BeLPT test favors berylliosis.
- History of exposure to beryllium (e.g., work in electronics, jewelry, sporting goods, dental industry, aerospace, ceramics, or nuclear weapons). (Murray 2022)
treatment
- Avoidance of any further beryllium exposure. Unfortunately, some patients may still progress to chronic berylliosis (even in the absence of any additional exposure).
- Steroid:
- Steroid is usually recommended for patients with substantial symptoms or decline in pulmonary function tests.
- It remains unclear whether steroid affects long-term outcomes.
- Dosing and taper may be similar to the management of pulmonary sarcoidosis: 📖
- Methotrexate may be used as a steroid-sparing agent (similarly to sarcoidosis).
basics
- Talc is used as a filler for many oral medications. If tablets are crushed and illicitly injected, this leads to talc embolism with subsequent talc granulomatosis. Talc has also been used to dilute (“cut”) heroin, in efforts to increase its street value.
- Talc granulomatosis causes intravascular and perivascular noncaseating granulomas, which may cause two processes:
- (1) Pulmonary arterial occlusion.
- (2) Parenchymal interstitial fibrosis.
- Some patients may have predominant pulmonary hypertension, or predominant interstitial fibrosis (depending on their individual response to the talc). (24394831)
- Other names for this disease are excipient lung disease or injection granulomatosis. Excipient lung disease might be the preferred name, because tablets contain a variety of fillers and substances other than talc.
epidemiology
- This usually results from injection of crushed tablets (e.g., hydromorphone, methylphenidate, amphetamines).
- Respiratory disease may present up to 30 years after exposure.
- Among people who use intravenous drugs, autopsy studies suggest a considerable rate of talc granulomatosis (which may remain largely asymptomatic and/or undetected).
- ⚠️ Talc granulomatosis may be a red herring that is unrelated to the patient's presenting symptoms.
symptoms
- Dyspnea is the predominant symptom.
- Progressive dyspnea on exertion occurs.
- Onset is often insidious, but it may also be subacute.
- Dry cough and constitutional symptoms may also occur.
- Eventually, pulmonary hypertension may develop (symptoms of pulmonary hypertension are discussed further here: 📖).
- Rarely, abrupt onset of pulmonary hypertension and cor pulmonale may occur following injection. (27726440)
radiology
imaging modality
- Chest radiograph has a sensitivity of perhaps ~50%. (Murray 2022)
- CT scan is needed to support a firm diagnosis.
two hallmark findings
- [1] Centrilobular nodules are the most frequent finding:
- 1-3 mm micronodules have a centrilobular distribution (reflecting distal periarterial granulomas). There may be a slight lower lobe predominance, given greater perfusion of the lower lobes.
- Nodules are often well-defined, but this may be difficult to discern (especially for smaller nodules).
- (The differential diagnosis of centrilobular nodules is here: 📖)
- [2] Pulmonary hypertension:
- Due to the angiocentric involvement, pulmonary hypertension may occur much earlier in this disease than in most other interstitial lung diseases. Thus, the degree of pulmonary hypertension may be disproportionately severe as compared to the amount of parenchymal disease.
- Radiologic evidence of pulmonary hypertension may include dilation of the right ventricle and pulmonary artery.
other potential findings
- Rarely, micronodules may coalesce, as in progressive massive fibrosis due to silicosis or coal workers pneumoconiosis. Eventually this can result in fibrosis and honeycombing that mimics severe sarcoidosis. (Walker 2019)
- Lower lobe panacinar emphysema may occur due to injection of methylphenidate (“Ritalin lung”).
radiological differential diagnosis
- Other causes of pulmonary hypertension plus centrilobular nodules are listed here: 📖
diagnosis
- Diagnosis may be challenging among patients who don't disclose a history of IV drug use.
- Tissue diagnosis (transbronchial or open-lung biopsy) may reveal perivascular foreign body granulomas containing birefringent crystals. Injected talc is usually 10 microns in size (as opposed to inhaled talc, which is ~5 microns).
- Fundoscopy commonly reveals talc crystals lodged in the retina (without causing visual symptoms). (24394831)
prognosis and treatment
- Unfortunately, retained talc may continue to incite an ongoing inflammatory response. Even following cessation of substance use, disease progression may occur (including the development of pulmonary hypertension).
- Cessation of intravenous drug use is obviously fundamental.
- Steroid is reported to transiently improve symptoms, in some cases. However, it's dubious whether steroid actually modifies the long-term course of the disease. Chronic steroid therapy may merely cause iatrogenic Cushing syndrome, wherein obesity and neuromuscular weakness exacerbate the respiratory failure.
basics
- Inhalational talcosis results from inadvertent inhalation of talc, usually in the form of talcum powder.
- Talc incites a granulomatous inflammatory response. Overall this disorder resembles sarcoidosis.
epidemiology
- Cosmetic use of talcum powder may be the most common source of exposure.
- Occupational exposure is also possible.
symptoms
- Patients may be asymptomatic, with radiologic abnormalities discovered incidentally.
- Unlike sarcoidosis, there should not generally be extrapulmonary signs/symptoms. (31174663)
radiology
- Small parenchymal nodules and reticular opacities may be seen in the mid-lung zones. (31174663) On CT scan, these may correspond with small centrilobular and subpleural nodules.
- Mediastinal and hilar lymphadenopathy can occur. Lymph nodes may contain areas of high attenuation, due to talc deposition. (Walker 2019)
investigations
- ACE levels (angiotensin-converting enzyme) may be elevated, due to granulomatous inflammation.
- Histologic evaluation reveals granulomas containing needle-shaped, polarizable crystals. (31174663)
management
- Prognosis is generally excellent, if further exposure can be avoided. (31174663)
basics
- Silicone embolization often results from injection of silicone in efforts to augment various body parts (e.g., illegal or poorly regulated cosmetic surgery).
- This has numerous parallels to fat emboli syndrome (FES).
- Eliciting an accurate history of silicone injection is central to the diagnosis.
- (Other pulmonary complications of silicone exposure may include progressive granulomatous inflammation or chronic silicone pneumonitis. Chronic silicone pneumonitis may result from rupture of silicone breast implants.) (25451364)
clinical manifestations
- Timing is variable:
- Acute illness typically develops within 72 hours of intravenous silicon injection. Inadvertent intravenous silicone injection may rarely cause immediate obstructive shock.
- Delayed onset could result from an initial deposit into the skin, with subsequent hematogenous spread following traumatization of the injection site. (34625180)
- Rarely, subacute onset may occur over months, due to recurrent embolization.
- Fever is common.
- Respiratory symptoms may be prominent:
- Cough.
- Hemoptysis may occur, which can be associated with diffuse alveolar hemorrhage.
- Chest pain.
- Respiratory failure may progress to ARDS.
- Petechiae.
- Neurologic impairment.
radiological findings
- CT scan often shows bilateral peripheral infiltrates and ground-glass patterns, with partial exclusion of centrilobular areas. (34625180)
bronchoscopy
- Bronchoscopy is not necessarily required (e.g., if the history, clinical presentation, and imaging features are strongly supportive of silicone embolization syndrome and other competing diagnoses can be excluded).
- Diffuse alveolar hemorrhage may be found in 60% of patients. (34625180)
- Cytology may reveal vacuolated “foamy” macrophages, due to the presence of silicone.
treatment
- Little is known regarding therapy, given the rarity of the condition.
- Treatment is predominantly supportive.
- For patients with high levels of systemic inflammation (e.g., markedly elevated C-reactive protein) and ARDS, steroid administration might be beneficial.
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Books:
- Shah, P. L., Herth, F. J., Lee, G., & Criner, G. J. (2018). Essentials of Clinical pulmonology. In CRC Press eBooks. https://doi.org/10.1201/9781315113807
- Shepard, JO. (2019). Thoracic Imaging The Requisites (Requisites in Radiology) (3rd ed.). Elsevier.
- Walker C & Chung JH (2019). Muller’s Imaging of the Chest: Expert Radiology Series. Elsevier.
- Palange, P., & Rohde, G. (2019). ERS Handbook of Respiratory Medicine. European Respiratory Society.
- Rosado-De-Christenson, M. L., Facr, M. L. R. M., & Martínez-Jiménez, S. (2021). Diagnostic imaging: chest. Elsevier.
- Murray & Nadel: Broaddus, V. C., Ernst, J. D., MD, King, T. E., Jr, Lazarus, S. C., Sarmiento, K. F., Schnapp, L. M., Stapleton, R. D., & Gotway, M. B. (2021). Murray & Nadel’s Textbook of Respiratory Medicine, 2-Volume set. Elsevier.
- Fishman's: Grippi, M., Antin-Ozerkis, D. E., Cruz, C. D. S., Kotloff, R., Kotton, C. N., & Pack, A. (2023). Fishman’s Pulmonary Diseases and Disorders, Sixth Edition (6th ed.). McGraw Hill / Medical.