A suspected case of hepatic reactive lymphoid hyperplasia in which EUS–fine needle aspiration contributed to the diagnosis

A 70-year-old female with a 10-year history of an incidentally diagnosed 8-mm hypoechoic lesion in the left lateral section of the liver on abdominal ultrasonography [Figures 1A and B] was evaluated for its gradual enlargement. Contrast-enhanced computed tomography showed homogeneous enhancement in the arterial-dominant phase and wash-out with suspicion of slight perinodular enhancement in the portal and late phases [Figures 2A–C]. Magnetic resonance imaging revealed high-signal intensity on diffusion-weighted imaging [Figure 2D] and slight signal intensity on T2-weighted imaging [Figure 2E].Figure 1: Ultrasound shows an 8-mm hypoechoic mass in the left lateral section of the liver on initial evaluation (A, B).Figure 2: Contrast-enhanced computed tomography shows homogeneous enhancement in the arterial dominant phase (A) and wash-out with suspicion of slight perinodular enhancement in the portal (B) and late phases (C). Magnetic resonance imaging shows high-signal intensity on diffusion-weighted imaging (D) and slight signal intensity on T2-weighted imaging (E).Hepatocellular carcinoma (HCC) could not be ruled out based on the imaging results, and given the lesion's location, EUS–fine needle aspiration (EUS–FNA) was performed. A space-occupying lesion (SOL) was observed in the left lateral section of the liver [Figure 3A], and a 22-gauge needle was used to obtain a sample via the stomach [Figure 3B]. No complications occurred post-biopsy.Figure 3: EUS shows a hypoechoic mass in the left lateral section of the liver (A). EUS–FNA was performed via the stomach (B).Histopathological examination findings showed lymphocyte clusters without atypia [Figure 4A], consisting predominantly of CD20-positive B cells [Figure 4B] and some CD3-positive T cells [Figure 4C]. In situ hybridization studies for kappa and lambda chains showed no light chain restriction, and Ki67-labeling yielded positive results (38%; Figure 4D). No lymphoepithelial lesion of the bile ducts representing a histological feature of MALT lymphoma was observed in the specimen. Taken collectively, a histological diagnosis of hepatic reactive lymphoid hyperplasia (RLH) was strongly suspected. This is consistent with studies on hepatic RLH reporting relatively high Ki-67 indices, with a mean value of 40%, indicative of the lesion's reactive proliferative nature.[1–4]Figure 4: Hematoxylin and eosin staining (A), immunostaining of CD20 (B), CD3 (C), and Ki67 (D) of the sample are shown (magnifications, ×400).Following EUS–FNA and pathological diagnosis, the patient underwent observation and monitoring. Despite over 1.5 years of imaging follow-up, the lesion showed no significant change. Imaging diagnosis of hepatic RLH can be challenging, with approximately 60% of cases being misdiagnosed as HCC or cholangiocarcinoma.[5] In such cases where imaging findings are suggestive of malignancy, surgical resection may be necessary for definitive diagnosis. This case highlights the utility and safety of EUS–FNA for obtaining a histological diagnosis of hepatic SOLs, especially for lesions localized in the left liver lobe.