Clinical scenario
Primary Sjögren's syndrome (pSS) is a chronic systemic autoimmune disease with estimated prevalence between 0.5% and 1% of the general population, predominantly affecting middle-aged women with a female to male ratio of 9:1 [1]. Clinical features range from glandular related symptoms (i.e. mucosal dryness) to systemic multi-organ manifestations and lymphoproliferative disorders. In this regard, it has been reported that B-cell lymphomas occur in 5%-10% of pSS patients, and the risk increases by 2,2% per year of age [2], with a 7-19 fold increased relative risk of developing non-Hodgkin’s lymphoma (NHL) compared to the general population [3]. Of the NHL associated to pSS, the most common is the mucosa-associated lymphoid tissue type (MALT) [4], which can occur in many mucosal sites such as orbits, naso-pharynx, stomach, thyroid and lung but, in pSS patients, is typically localized in major SGs.
Role of imaging and biopsy
MALT lymphoma can be suspected in patients with certain clinical features, such as persistent SGs enlargement, splenomegaly, lymphadenopathies, and/or laboratory findings, such as, but not limited to, leukopenia, anti-Ro/SSA or/and anti‐La/SSB and rheumatoid factor (RF) positivity and C4 hypocomplementemia [5]. US can have a role in identifying major SGs architectural changes suspicious for MALT lymphoma [6] and can be used as a guide for percutaneous sampling.
Usually, in focal lesions of major SGs, the diagnosis relies on fine-needle aspiration cytology (FNAC), a technique that is safe, but that not infrequently fails to provide enough material for diagnosis [7] with consequent need for surgical sampling [8,9]. On the other hand, surgical biopsy usually (not always [10]) provides enough material for diagnosis, but can have significant, even permanent, adverse effects, the most serious being facial nerve damage, scialoceles and salivary fistulae [11].
Recent evidence shows that US-guided Core Needle Biopsy (CNB) has the potential to overcome both FNAC and surgical limitations. Compared to FNAC, CNB is able to improve diagnosis since it preserves tissue architecture and provides enough tissue material for pathological examination in almost all cases, allowing immunohistochemical staining and flow cytometry [12,10]. Compared to surgical biopsy, CNB has a reduced chance of causing serious complications, with comparable diagnostic value [10].
Our experience
We recently performed a series of 13 US-guided CNB on focal lesions of major SGs in patients with pSS and clinically and/or US suspected MALT lymphoma. Considering that no standardized procedures for US-guided CNB sampling of major SGs are described in literature, we developed our own technique together with our multidisciplinary team.
Purpose
We aim to provide a step-by-step guide on how to safely perform CNB of the major SGs, with a special focus on how to minimize the chances to cause facial nerve damage.