2437 Solitary Fibrous Liver Tumor Diagnosed With EUS-Guided Fine-Needle Biopsy: Case Review

Abstract

INTRODUCTION: Attaining SFLT's diagnosis is challenging as there are no specific clinical nor radiological characteristics to follow. Therefore, diagnosis is mainly sought based on histologic features (vascularity, mitosis, necrosis, etc.). We report a case of SFLT in a 73-year-old female diagnosed serendipitously by Endoscopic Ultrasound (EUS) - Fine Needle Biopsy (FNB), histologic, and immunophenotypic findings combined. CASE DESCRIPTION/METHODS: A 73-year-old female patient presented with moderate RUQ abdominal pain for 1 month and pristine lab work. Patient denied relevant past medical history. MRI with and without contrast, showed a 12.8 cm × 11.2 cm mass in the anterior segment of the right hepatic lobe and no signs of hepatic steatosis. The diagnosis was made by an EUS-FNB ambulatory procedure performed with a 19-g needle. EUS disclosed a hypoechoic and heterogenous mass and non-alcoholic steatohepatitis (NASH). FNB preliminarily showed a spindle cell lesion. The combined histologic and immunophenotypic findings were: Vimectin and CD34 positive; Smooth Muscle Actin – rare faint positive staining. Prognostication was deferred for the resection of the specimen. Metastasis were to be excluded clinically. DISCUSSION: Less than 100 cases of SFLT have been reported worldwide. Classically, it presents itself as benign, predominantly in females around the 5th decade, and with a 2:1 female:male ratio. Clinically, it is mainly asymptomatic, or it can depict constitutional symptoms when malignant. Radiologically, suggestive findings are non-diagnostic; making histopathological features (i.e., spindle shaped cells) critical markers to reach a diagnosis. EUS - FNB yields an advantage over Fine Needle Aspiration (FNA) in diagnosing tissues which require immunohistochemical staining - such as this one - in two ways: FNB renders a core biopsy sample (preserved tissue architecture) and is more affordable; whereas FNA requires bedside rapid onsite evaluation, increasing the overall cost. Surgical resection, adjuvant chemotherapy, and radiotherapy may be required for an effective treatment. In our case study, the patient was a 73-year-old female, which is an uncommonly reported age population. Therefore, despite SFLT's infrequent presentation, this entity should be considered in the differential diagnosis of liver tumors. Lastly, EUS-FNB is a safer and affordable procedure to reach SFLT's definitive diagnosis in comparison to other more invasive/expensive methods (i.e., Percutaneus Liver Biopsy, EUS-FNA respectively).