Imaging Pearls ❯ Chest ❯ Sarcoidosis
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- Sarcoidosis is a multisystem disorder of unknown origin and poorly understood pathogenesis that predominantly affects lungs and intrathoracic lymph nodes and is characterized by the presence of noncaseating granulomatous inflammation in involved organs. The disease is highly heterogeneous and can mimic a plethora of other disorders, making diagnosis a challenge even for experienced physicians. The evolution and severity of sarcoidosis are highly variable: many patients are asymptomatic and their disease course is generally benign with spontaneous resolution. However, up to one-third of patients develop chronic or progressive disease mainly due to pulmonary or cardiovascular complications that require long-term therapy. The diagnosis of sarcoidosis requires histopathological evidence of noncaseating granulomatous inflammation in one or more organs coupled with compatible clinical and radiological features and the exclusion of other causes of granulomatous inflammation; however, in the presence of typical disease manifestations such as Löfgren’s syndrome, Heerfordt’s syndrome, lupus pernio and asymptomatic bilateral and symmetrical hilar lymphadenopathy, the diagnosis can be established with high level of certainty on clinical grounds alone.
Pulmonary Sarcoidosis: Diagnosis and Differential Diagnosis.
Bernardinello N, Petrarulo S, Balestro E, et al.
Diagnostics (Basel). 2021 Aug 28;11(9):1558.. - “Overall, the average age of onset in most studies is between 47 and 51 years, with the peak ages of onset closer to 30–55 years. Sarcoidosis is rare in the pediatric population, whereas approximately 30% of cases occur in elderly patients.”
Pulmonary Sarcoidosis: Diagnosis and Differential Diagnosis.
Bernardinello N, Petrarulo S, Balestro E, et al.
Diagnostics (Basel). 2021 Aug 28;11(9):1558.. - Chest high resolution CT (HRCT) is more sensitive than chest X-ray and provides a more precise assessment of hilar, mediastinal and parenchymal abnormalities . A typical HRCT feature in sarcoidosis is the presence of well-defined micronodules scattered along the broncho-vascular bundle, veins, fissures and pleura in a characteristic lymphatic distribution. The micronodules can be confluent, leading to mass-like conglomerations and distortion of the lung parenchyma . Occasionally, conglomerate masses are surrounded by a multitude of micronodules, hence the term “galaxy sign”, which is highly suggestive of pulmonary sarcoidosis. All these abnormalities typically display a mid-to-upper zone predominance.
Pulmonary Sarcoidosis: Diagnosis and Differential Diagnosis.
Bernardinello N, Petrarulo S, Balestro E, et al.
Diagnostics (Basel). 2021 Aug 28;11(9):1558.. - “Additional HRCT findings include ground glass opacities and septal and nonseptal lines. Up to 20% of cases develop pulmonary fibrosis, which manifests on HRCT as bronchial distortion (40% of cases), honeycombing (26% of cases) and linear scarring (14% of cases). Complications of fibrotic pulmonary sarcoidosis include pulmonary hypertension and mycetoma, with hemoptysis representing a rare but potentially life-threatening manifestation.”
Pulmonary Sarcoidosis: Diagnosis and Differential Diagnosis.
Bernardinello N, Petrarulo S, Balestro E, et al.
Diagnostics (Basel). 2021 Aug 28;11(9):1558.. - “Due to the lack of a diagnostic gold standard and the absence of a specific aetiology, the diagnosis of sarcoidosis remains one of exclusion. In addition, granulomatous inflammation is the histologic hallmark of a number of conditions, including bacterial, mycobacterial and fungal infection, and occupational lung diseases such as chronic beryllium disease and silicosis. Occasionally, granulomatous inflammation may result from an immunological response against neoplastic antigens or drugs.”
Pulmonary Sarcoidosis: Diagnosis and Differential Diagnosis.
Bernardinello N, Petrarulo S, Balestro E, et al.
Diagnostics (Basel). 2021 Aug 28;11(9):1558..
- “Sarcoidosis is a granulomatous disorder of unknown etiology characterized by noncaseating granulomas virtually in every organ and tissue. This finding represents the most important diagnostic clue to reach a correct definition of sarcoidosis, although the biopsy is invasive and has several risk procedures. Several efforts are made to suspect the diagnosis of sarcoidosis by combining noninvasive elements, in particular from imaging, though these findings are often nonspecific and reflect the wide multifactorial pathogenesis. Every effort should be made to obtain a detailed radiological picture that, if associated with a suggestive clinical picture, could avoid the need of biopsy in some specific cases.”
CT Findings in Pulmonary and Abdominal Sarcoidosis. Implications for Diagnosis and Classification.
Tana C, Donatiello I, Coppola MG, et al.
J Clin Med. 2020;9(9):3028. Published 2020 Sep 20. doi:10.3390/jcm9093028 - "Sarcoidosis is a multifaceted disease where the clinical picture can be totally asymptomatic at the onset (in up to 50% of cases) and clinical manifestations, when present, may be nonspecific and vary depending on the involved organs, and virtually any tissue can be affected. Since almost all organs can be affected by the disease, imaging techniques play an important role in the diagnosis of this disorder, and lung, abdominal sites, heart and brain are the main fields to detect the localization of the disease. Brain contrast-enhanced CT (CECT) and magnetic resonance imaging (MRI) of the heart can be useful to detect nodules and tissue enhancement (e.g., myocardium) in these districts.”
CT Findings in Pulmonary and Abdominal Sarcoidosis. Implications for Diagnosis and Classification.
Tana C, Donatiello I, Coppola MG, et al.
J Clin Med. 2020;9(9):3028. Published 2020 Sep 20. doi:10.3390/jcm9093028 - "In the past, before the diffusion of high-resolution CT (HRCT), which allows a clearer definition of the interstitium impairment from sarcoidosis, lung involvement patterns were defined based on the Scadding classification at chest X-ray. This classification defines as stage I the presence of bilateral hilar adenopathy, stage II bilateral hilar adenopathy and pulmonary infiltrates, stage III pulmonary infiltrates without overt hilar adenopathy , and stage IV the presence of overt pulmonary fibrosis. Through HRCT examination, it has been shown that many radiological pictures classified as a 0–1 stage Scadding at X-rays presented even “more minimal” parenchymal alterations compatible with the disease.”
CT Findings in Pulmonary and Abdominal Sarcoidosis. Implications for Diagnosis and Classification.
Tana C, Donatiello I, Coppola MG, et al.
J Clin Med. 2020;9(9):3028. Published 2020 Sep 20. doi:10.3390/jcm9093028 - “Because of their typical lymphatic predilection, the nodules are mainly grouped along the bronchial vascular bundles, interlobular septa, interlobar fissures, and subpleural areas . The nodules also affect the middle and upper lung fields and can merge to form larger opacities. The distribution of the granulomas (peribronchial and intraluminal) can explain the air trapping which reflects the involvement of the small airways, and can be detected more easily with expiratory HRCT scans. This regional air trapping is almost constant in all cases of sarcoidosis.”
CT Findings in Pulmonary and Abdominal Sarcoidosis. Implications for Diagnosis and Classification.
Tana C, Donatiello I, Coppola MG, et al.
J Clin Med. 2020;9(9):3028. Published 2020 Sep 20. doi:10.3390/jcm9093028 - “The galaxy sign at HRCT is also highly suggestive of sarcoidosis and consists of a large nodule, usually with irregular margins, resulting from the coalescence of numerous smaller satellite nodules. Another relatively new finding at HRCT consists of the “sarcoid cluster sign”, described for the first time by Herraez Ortega, characterized by the grouping of small point nodules at the periphery of the lungs.”
CT Findings in Pulmonary and Abdominal Sarcoidosis. Implications for Diagnosis and Classification.
Tana C, Donatiello I, Coppola MG, et al.
J Clin Med. 2020;9(9):3028. Published 2020 Sep 20. doi:10.3390/jcm9093028 - "In addition to presenting with typical radiological characteristics, sarcoidosis can manifest with a wide spectrum of atypical HRCT images such as unilateral and asymmetric hilar or mediastinal lymphadenopathy of the parenchyma that mimic a mass, ground-glass opacity, miliary distribution of opacities, thickening of the interlobar septa and fibrocystic changes shows some CT features of pulmonary sarcoidosis. Even if chest HRCT has several advantages in terms of the detection of nodules that are not otherwise evident on chest x-rays, sometimes it is too detailed and can show a plethora of patterns that could be misdiagnosed with those observed in other disorders if not analyzed correctly.”
CT Findings in Pulmonary and Abdominal Sarcoidosis. Implications for Diagnosis and Classification.
Tana C, Donatiello I, Coppola MG, et al.
J Clin Med. 2020;9(9):3028. Published 2020 Sep 20. doi:10.3390/jcm9093028 - “Tuberculosis (TB) should always enter into differential diagnosis with sarcoidosis, especially in the high-risk areas considered and in immunocompromised patients. More specific characteristics of TB reactivation are the HRCT presence of exudative lesions, acinar nodules and the tree-in-bud sign. Lymph node calcifications from TB can be recognized because they are denser than in sarcoidosis and tend to be more often unilateral, while in sarcoidosis, they are more often bilateral.”
CT Findings in Pulmonary and Abdominal Sarcoidosis. Implications for Diagnosis and Classification.
Tana C, Donatiello I, Coppola MG, et al.
J Clin Med. 2020;9(9):3028. Published 2020 Sep 20. doi:10.3390/jcm9093028
- “Sarcoidosis is a chronic inflammatory dis- ease characterized by CD4+ T-cell activation and recruitment, macrophage accumulation, and development of sterile noncaseating epithelioid granulomas. Dominant expression of interferon is a defining feature of active sarcoidosis. The cause is not entirely clear and likely related to a complex interplay between environmental and genetic factors. Although the lungs are most commonly affected, nearly any organ in the body can be involved. Other commonly involved tissues include lymph nodes, skin, liver, and eyes.”
Sarcoidosis: A Diagnosis of Exclusion
Lee GM et al.
AJR 2020; 214:50–58 - "Sarcoidosis occurs worldwide and may affect men and women of all ages and races; however, sarcoidosis is most commonly seen in women, blacks, and individuals between the ages of 20–40 years old. First-degree relatives of patients with sarcoidosis are at increased risk for the disease. Furthermore, there is geographic variation in the prevalence of sarcoidosis, with highest prevalence observed in African Americans and Northern Europeans. Socioeconomic status does not affect the risk of developing sarcoidosis; however, financial barriers to medical care are associated with more severe manifestations at presentation.”
Sarcoidosis: A Diagnosis of Exclusion
Lee GM et al.
AJR 2020; 214:50–58 - “About half of all patients with sarcoidosis are asymptomatic at presentation, with imaging abnormalities detected incidentally on chest radiography performed for other reasons. When patients are symptomatic, the most common presenting thoracic symptom is persistent cough with other common symptoms including dyspnea, chest pain, wheezing, night sweats, and fatigue.”
Sarcoidosis: A Diagnosis of Exclusion
Lee GM et al.
AJR 2020; 214:50–58 - "In the United States and Europe, sarcoidosis-related death is most commonly attributable to pulmonary fibrosis with respiratory failure, whereas in Japan, cardiac lesions are found to be the leading contributor on autopsy. When abnormal, pulmonary function tests typically show a restrictive pattern with decreased carbon monoxide diffusing capacity. Pulmonary hypertension is a well-described complication of sarcoidosis, termed “sarcoidosis-associated pulmonary hypertension.”
Sarcoidosis: A Diagnosis of Exclusion
Lee GM et al.
AJR 2020; 214:50–58 - “The most common radiographic finding is well-defined mediastinal and hilar lymph adenopathy which occurs in an estimated 95% of cases. The classically described 1-2-3 pattern, also known as the Garland triad, is the combination of right paratracheal, right hilar, and left hilar lymph node enlargement. Additional studies have shown that the most common radiographic pattern shows left-sided mediastinal nodes, particularly aortico- pulmonary window lymph nodes, in addition to bilateral hilar and right paratracheal lymph nodes. This pattern is known as the more aptly named “1-2-3-4 pattern”.”
Sarcoidosis: A Diagnosis of Exclusion
Lee GM et al.
AJR 2020; 214:50–58 - "Thoracic sarcoidosis manifests with numerous patterns and nonspecific findings with a broad initial differential diagnosis including infectious, inflammatory, and neoplastic causes. Typical findings include hilar and right paratracheal lymphadenopathy and perilymphatic upper lung zone–predominant micronodules. However, in a significant minority of patients, the diagnosis is not straightforward. For this reason, sarcoidosis has been termed the “great mimicker.”
Sarcoidosis: A Diagnosis of Exclusion
Lee GM et al.
AJR 2020; 214:50–58
- Sarcoidosis: Facts
- Most common in age range of 30-50
- AfroAmericans affected 3x more frequent then whites
- Pulmonary complications most common cause of death
- Symptoms include fatigue, fever and weight loss - HRCT in Sarcoidosis
- Systemic disorder of unknown origin
- Pulmonary findings in 90%
- Perilymphatic nodules
- Upper and mid lung predominance
- Hilar and paratracheal nodes
- About 20% progress to fibrosis - Random Pulmonary Nodules: Differential Dx
- Langerhans cell histiocytosis
- Hematologic metastases
- Miliary TB / fungus
- Sarcoidosis (uncommon) - Perilymphatic Nodules: differential diagnosis
- sarcoidosis (common)
- lymphangitic spread of tumor (uncommon)
- silicosis and CWP (uncommon)
- amyloidosis (rare)
- lymphoid interstitial pneumonia (LIP; rare)