What is the bronchoalveolar lavage (BAL) report for Sarcoidosis?

From the Guidelines

A bronchoalveolar lavage (BAL) report for sarcoidosis should be interpreted with caution, considering the clinical context and correlation with other diagnostic criteria, as it can show an increased number of lymphocytes with a CD4/CD8 T-cell ratio greater than 3.5, which is highly suggestive of sarcoidosis, as noted in the 2020 American Thoracic Society clinical practice guideline 1. When evaluating a BAL report for suspected sarcoidosis, it is essential to consider the following key points:

• The report may show a normal or slightly elevated total cell count with a predominance of macrophages, minimal neutrophils, and few or no eosinophils.
• The absence of infectious organisms, malignant cells, and other pathological findings helps rule out alternative diagnoses.
• The lymphocytosis and elevated CD4/CD8 ratio reflect the characteristic T-cell mediated immune response that occurs in sarcoidosis, where activated CD4+ T-cells accumulate in affected tissues and drive granuloma formation.
• However, as suggested by the 2012 American Thoracic Society clinical practice guideline 1, lymphocyte subset analysis should not be a routine component of BAL cellular analysis, but rather performed if a lymphocytic disease is suspected or the initial BAL cellular findings identify a lymphocytosis. The diagnosis of sarcoidosis should be based on a combination of clinical symptoms, radiographic findings, and potentially tissue biopsy results showing non-caseating granulomas, rather than relying solely on BAL results. Some key considerations when interpreting BAL results include:
• Correlating BAL findings with clinical symptoms and radiographic findings, particularly bilateral hilar lymphadenopathy on chest imaging.
• Considering the potential for sarcoidosis-like granulomatous reactions in association with several medications, including immunotherapeutics, such as immune checkpoint inhibitors, anti–TNF-a, and other conditions, as noted in the 2020 guideline 1.
• Being aware that the CD4/CD8 ratio may not be significantly increased in a substantial number of patients with sarcoidosis, and can change during the course of the disease process, as discussed in the 2012 guideline 1.

From the Research

Sarcoidosis BAL Report

• Sarcoidosis is a multisystem inflammatory disorder with unclear etiology, and a tissue diagnosis is often necessary to illustrate the non-caseating granulomas on histopathology 2.
• Bronchoalveolar lavage (BAL) fluid analysis can be helpful in the differential diagnosis of sarcoidosis, with a grouping of features including an elevated total cell count, predominantly lymphocytes, and a nearly normal percentage of eosinophils and polymorphonuclear neutrophils 3.
• The CD4/CD8 ratio in BAL fluid can be used to differentiate sarcoidosis from other interstitial lung diseases, with an optimal cutoff value of 3.7 having a specificity of 96.8% and a sensitivity of 43.2% 4.
• The diagnostic accuracy of the CD4/CD8 ratio in BAL fluid can vary depending on the clinical and radiographic manifestation of sarcoidosis, with optimal cutoff points of 3.5 and 4.0 for asymptomatic and symptomatic patients, respectively 5.
• BAL fluid analysis has less clinical relevance in the follow-up and depiction of prognosis and response to treatment, but can be useful in the initial diagnosis of sarcoidosis 3.
• The use of BAL in the diagnostic pathway of pulmonary sarcoidosis is valuable, but results must be interpreted considering the specific clinical case, and the CD4/CD8 ratio depends on clinical and radiographic manifestation 5.
• Advances in bronchoscopic equipment and techniques have made it possible to obtain tissue samples using minimally invasive techniques, avoiding invasive open lung biopsy and its associated risks 2.