The guidelines were published in the American Journal of Respiratory and Critical Care Medicine, in an article titled “Diagnosis and Detection of Sarcoidosis. An Official American Thoracic Society Clinical Practice Guideline.”
Sarcoidosis is an inflammatory disease characterized by the formation of clumps of inflammatory cells called granulomas. At present, there is no standardized way to diagnose sarcoidosis. Rather, the disease is diagnosed based on three criteria: clinical presentation, finding sarcoidosis-like granulomas in tissue biopsies, and excluding other potential reasons for granulomas.
“There are no universally accepted measures to determine whether each diagnostic criterion has been satisfied,” Elliott D. Crouser, MD, professor at The Ohio State University Wexner Medical Center and co-author of the guidelines, said in a press release. “Therefore, the diagnosis of sarcoidosis is never fully certain.”
The new guidelines were created by a panel of experts, who reviewed available scientific evidence. Their recommendations were based on a series of guiding questions about whether particular diagnostic tests should be performed in specific circumstances.
The recommendations were broadly broken into three sections. The first section is about when to conduct lymph node sampling. Lymph nodes are immunological structures, and are commonly found swollen in the chest of sarcoidosis patients.
In sarcoidosis, enlarged lymph nodes are generally asymptomatic, and taking tissue samples does not usually provide additional information. Therefore, the guidelines do not recommend lymph node sampling in people who, based on their clinical presentation and other factors, are at high clinical suspicion of sarcoidosis.
However, for people with no clear diagnosis but who have swollen lymph nodes in their chest, the guidelines make no recommendation on whether to sample or not. This is because no useful information would be obtained in most cases, but these swollen lymph nodes could, in rare instances, indicate cancer or infection requiring treatment.
For people who do not undergo lymph node sampling, the guidelines suggest, “close clinical follow-up.”
For those who undergo the procedure, the experts suggest a less invasive technique called endobronchial ultrasound (EBUS)-guided lymph node sampling, instead of conventional mediastinoscopy.
The second section of guidelines focuses on screening for extra-pulmonary disease, which tests for the involvement of organs without obvious symptoms in people who have been diagnosed with sarcoidosis.
The guidelines generally favor testing for the involvement of multiple organs, such as the kidneys, liver, heart, and eyes, even in the absence of obvious symptoms related to these organs. For example, the guidelines suggest that blood markers related to kidney and liver health should be assessed, with specific recommendations related to different individual markers.
The guidelines also recommend testing for hypercalcemia (high calcium levels). This was the only “strong recommendation,” with the others considered “conditional.” The reason for testing calcium levels is that it’s fairly easy to do, and high levels are often associated with kidney damage.
In the third section, the guidelines highlight diagnostic tests that should be taken to identify suspected heart involvement or pulmonary hypertension (PH; high blood pressure in lung arteries).
For heart involvement, the guidelines recommend magnetic resonance imaging (MRI) over positron emission tomography (PET). When MRI is not available, PET is preferred over transthoracic echocardiogram (TTE). For PH, the guidelines suggest initial testing with TTE, followed by right heart catheterization if TTE results suggest PH.
Although a large body of related data has been published, “very few of these studies were properly designed to guide clinical practice,” the experts wrote.
“The quality of evidence was poor in most cases, reflecting the need for additional high quality research to guide clinical practice” in the diagnosis and detection of sarcoidosis, Crouser said.
Due to this low-quality evidence, the guidelines are recommendations, not mandates, that clinicians can individualize for each patient.
“Clinicians are encouraged to apply the recommendations within the clinical context of each individual patient, including the patient’s values and preferences,” the team wrote, adding that these recommendations, “should be revisited as new evidence becomes available.”
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