Editorial

Course and prognosis of sarcoidosis around the world

Sarcoidosis is a multisystemic granulomatous disease of unknown etiology. The diagnostic can be made by histological identification of non-caseous granuloma or by a combination of clinical criteria. Active inflammatory granuloma can lead to fibrotic damage. Although 50% of cases resolve spontaneously, systemic treatments are often necessary to decrease symptoms and avoid permanent organ dysfunction, notably in cardiac sarcoidosis. The course of the disease can be punctuated by exacerbations and relapses and the prognostic depends mainly on affected sites and patient management. FDG-PET/CT along with newer FDG-PET/MR have emerged as key imaging modalities in sarcoidosis, namely for certain diagnostic purposes, staging and biopsy guiding. By identifying with a high sensitivity inflammatory active granuloma, FDG hybrid imaging is a main prognostic tool and therapeutic ally in sarcoidosis. This review aims to highlight the actual critical roles of hybrid PET imaging in sarcoidosis and display a brief perspective for the future which appears to include other radiotracers and artificial intelligence applications.

Sarcoidosis is a sterile non-necrotizing granulomatous disease without known causes that can involve multiple organs with a predilection for the lung and thoracic lymph nodes. Worldwide it is estimated to affect 2–160/100,000 people and has a mortality rate over 5 years of approximately 7%. For sarcoidosis patients, the cause of death is due to sarcoid in 60% of the cases, of which up to 80% are from advanced cardiopulmonary failure (pulmonary hypertension and respiratory microbial infections) in all races except in Japan were greater than 70% of the sarcoidosis deaths are due to cardiac sarcoidosis.

Scadding stages for pulmonary sarcoidosis associates with clinical outcomes. Stages I and II have radiographic remission in approximately 30%–80% of cases. Stage III only has a 10%–40% chance of resolution, while stage IV has no change of resolution. Up to 40% of pulmonary sarcoidosis patients progress to stage IV disease with lung parenchyma fibroplasia, bronchiectasis with hilar retraction and fibrocystic disease. These patients are at highest risk for the development of precapillary pulmonary hypertension, which may occur in up to 70% of these patients. Sarcoid patients with pre-capillary pulmonary hypertension can respond to targeted pulmonary arterial hypertension medications. Stage IV fibrocytic sarcoidosis with significant pulmonary physiologic impairment, >20% fibrosis on HRCT or pre-capillary pulmonary hypertension have the highest risk of mortality, which can be >40% at 5-years.

First line treatment for patients who are symptomatic (cough and dyspnea) with parenchymal infiltrates and abnormal pulmonary function testing (PFT) is oral glucocorticoids, such as prednisone with a typical starting dose of 20–40 mg daily for 2 weeks to 2 months. Prednisone can be tapered over 6–18 months if symptoms, spirometry, PFTs, and radiographs improve. Prolonged prednisone may be required to stabilize disease. Patients requiring prolonged prednisone ≥10 mg/day or those with adverse effects due to glucocorticoids may be prescribed second and third line treatements. Second and third line treatments include immunosuppressive agents (e.g., methotrexate and azathioprine) and anti-tumor necrosis factor (TNF) medication; respectively. Effective treatments for advanced fibrocystic pulmonary disease are being explored. Despite different treatments, relapse rates range from 13% to 75% depending on the stage of sarcoid, number of organs involved, socioeconomic status, and geography.

The mortality rate for sarcoidosis over a 5 year follow up is approximately 7%. Unfortunately, 10%–40% of patients with sarcoidosis develop progressive pulmonary disease, and >60% of deaths resulting from sarcoidosis are due to advance cardiopulmonary disease. Oral glucocorticoids are the first line treatment, while methotrexate and azathioprine are considered second and anti-TNF agents are third line treatments that are used solely or as glucocorticoid sparing agents for symptomatic extrapulmonary or pulmonary sarcoidosis with infiltrates on chest radiographs and abnormal PFT. Relapse rates have ranged from 13% to 75% depending on the population studied.

Erythema Nodosum (EN) is the most common skin manifestation in sarcoidosis and has often been associated with a good prognosis.

To compare the clinical characteristics and treatment-related features in patients with sarcoidosis according to whether or not EN was seen as a presenting symptom at the time of diagnosis.

A 20-year single-center retrospective study was performed. The following two groups were identified: one group with EN as one of the presenting symptoms at the time of diagnosis of sarcoidosis (EN group) and a second group without EN as a presenting symptom at diagnosis (non-EN group). The clinical characteristics and treatment modalities were collected from the medical records.

A total of 122 patients (31 in the EN group, 91 in the non-EN group) were included. Radiological stages of pulmonary disease were significantly lower in the EN group. Articular involvement was more common in the EN group (p = 0.001), whereas other systemic organ involvements (p = 0.025), especially neurological involvement (p = 0.036), were significantly more common in the non-EN group. In the EN group, a higher percentage of patients were managed without systemic therapy (71.0% vs. 54.9%) and spontaneous remission was more frequent (25.0% vs. 14.1%), however, this wasn’t statistically significant.

Retrospective design.

The lower radiological stage of pulmonary sarcoidosis and lower frequency of systemic organ involvement in patients with EN augment the prognostic value of EN highlighted in the literature. However, this study couldn’t confirm that the patients with EN would need less systemic therapy in the course of their disease.

Sarcoidosis is a disease characterized by non caseous necrotizing granuloma with multiple systems and organs. About 25%–80% of patients have ocular involvement. Here we present an extremely rare case of sarcoid uveitis.

A 54-year-old woman with diabetes for 5 years presented with a 4-month dark flutter in her left eye. She first diagnosed as having left eye fungal endophthalmitis because of the vitritis and obvious haze. She underwent a pars plana vitrectomy surgery, after which intraocular fluid was send out for fungus detection. However, no fungus infection was found. Then the result of her chest CT scan draw our attention which revealed multiple enlarged lymph nodes in mediastinum. After endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) biopsy of enlarged hilar intrathoracic lymph nodes, her histological diagnosis was sarcoidosis. After topical and systemic steroids treatments, the visual acuity was improved.

Eye involvement may be the first sign of sarcoidosis. Clinical differences such as string of pearl-type vitreous opacities are sometimes not enough for differential sarcoid uveitis and fungal endophthalmitis. The laboratory intraocular fluid analysis is one of the contributor to the final differential diagnosis.

Sarcoidosis is an idiopathic multisystem disorder characterized by noncaseating granulomas. The article focuses on the typical imaging manifestations of sarcoid and the common differentials that need to be included when appropriate. Mistaking a sarcoid-mimicking disease for sarcoid can result in increased patient morbidity and mortality. The pulmonary system is the most common system involved and is typically the best understood by the radiologist, however a deeper knowledge of the pulmonary findings and features of sarcoid in other organ systems is critical. There is a myriad of sarcoid imaging manifestations that can involve every organ system. Often a confidant diagnosis of sarcoid can be made, however a broad differential may need to be considered- differential diagnoses include primary neoplasm, metastatic disease, infectious, and inflammatory etiologies. Radiologist familiarity with the multimodality multisystem imaging findings of sarcoid can help guide clinical management and optimize patient care.