**1. Introduction**

Microscopic findings involving lymphocytic infiltration surrounding the excretory ducts in combination with the destruction of acinar tissue are representative for both minor and major salivary glands and are pathognomonic changes for SS. Parotid, lip, or sublingual salivary gland biopsy is performed in the diagnosis and monitoring of SS, but currently only labial salivary gland biopsy (LSGB) is included into classification criteria of SS. LSGB is used for the diagnosis of Sjögren's syndrome (SS). The current classification criteria of SS, approved by the American College of Rheumatology (ACR) and the European League against Rheumatism (EULAR) in 2016, include LSGB as a part of weighted sum of five items [1]. The presence of focal lymphocytic sialadenitis (FLS) with a focus score of 1 foci/4 mm2 glandular tissue is a positive score of LSGB. Lip salivary glands are widely distributed in the labial mucosa of the oral cavity. They are largely used for assisting the diagnosis of SS, because they are easily accessible and lie above the muscle layer. They are separated from the oral mucous membrane by a thin layer of fibrous connective tissue. Orientation and identification of glandular tissue is the easiest. The risk of excessive postoperative bleeding is decreased because the arterial supply to the lip lies deep. These anatomical implications and pathognomic changes predispose of labial salivary glands to the biopsy [1–7].
