Minor salivary gland biopsy for the diagnosis of neurosarcoidosis

Introduction: The definite diagnosis of neurosarcoidosis is challenging since it requires a compatible histology of the nervous system. When neurosarcoidosis is suspected, other systemic manifestations are investigated to confirm the diagnosis. A minor salivary gland biopsy (MSGB) is often performed since it is minimally invasive. The objective of the present study was to assess its performance for the diagnosis of neurosarcoidosis. Methods: A retrospective single-center study included patients who underwent a MSGB in a tertiary neurological university hospital (Lyon, France) between 2015 and 2018. Clinical presentations unlikely to be compatible with neurosarcoidosis were excluded. Positive cases of neurosarcoidosis were defined as definite, probable, and possible cases, according to the latest international neurosarcoidosis diagnostic criteria from the Neurosarcoidosis Consortium Consensus Group. Results: A total of 529 patients underwent a MSGB for clinical manifestations compatible with neurosarcoidosis. Among the 13 who fulfilled the criteria for neurosarcoidosis, only one had a positive MSGB. The sensitivity of MSGB was 7.7% (95% CI [0.2–36.0%]) and the specificity was 100.0% (95% CI [99.3–100%]). Discussion/Conclusion: Considering the low sensitivity of MSGB for the diagnosis of NS, MSGB should be performed in selected indications, including a suspicion of spinal cord sarcoidosis, or when there is a strong clinical, laboratory and radiological suspicion of NS. MSGB should rather not be performed when the chest CT-scan does not show signs of pulmonary or lymph node sarcoidosis.