Caitlyn J. Smith, BS, Katsiaryna Laziuk, MD, Deepthi Rao, MD University of Missouri, Columbia, MO
Introduction: Metastatic urothelial carcinoma of the bladder is generally considered an aggressive disease. It has the potential to metastasize to lymph nodes, bones, lungs, liver, and peritoneum. The accurate diagnosis of metastatic urothelial carcinoma is challenging especially in the setting of histological mimickers. Without pathological expertise and additional immunohistochemistry, metastatic tumors could remain incorrectly diagnosed and delay therapeutic intervention.
Case Description/Methods: Herein, we describe a 62-year-old man who presented with jaundice, elevated LFTs, diffuse abdominal pain, and early satiety. MRI of the abdomen revealed a hilar hyperintense mass involving the common bile duct, bilateral hepatic ducts causing narrowing, a 1.1 cm mass in segment 6, and hydroureteronephrosis with thickening of the renal pelvis.
Discussion: Clinical differential diagnosis included cholangiocarcinoma and other tumors including a metastatic neuroendocrine tumor (NET). Microscopic evaluation of liver mass biopsy revealed insular growth pattern with monotonous epithelioid cells arranged in nests morphologically suggestive of well-differentiated neuroendocrine tumor (WDNET). However, neuroendocrine immunohistochemical stains, including synaptophysin, chromogranin, and CD56, were all negative, and the Ki-67 staining was 37%, higher than expected for a WDNET, (See Figure) prompting broadening of the differential. Following further workup, a diagnosis of metastatic urothelial carcinoma was confirmed by immunopositivity for immunohistochemical markers P40, and GATA3 (See Figure).
Familiarity with tumors that are histologically identical is critical. Considering an appropriate differential diagnosis, and following a stepwise immunohistochemical approach will be crucial in spotting the mimickers and rendering appropriate management promptly.
Caitlyn Smith indicated no relevant financial relationships.
Katsiaryna Laziuk indicated no relevant financial relationships.
Deepthi Rao indicated no relevant financial relationships.
Caitlyn J. Smith, BS, Katsiaryna Laziuk, MD, Deepthi Rao, MD. C0722 - Spotting the Deceiver: Metastatic Urothelial Carcinoma to the Liver Masquerading as a Well-Differentiated Neuroendocrine Tumor Histologically, ACG 2022 Annual Scientific Meeting Abstracts. Charlotte, NC: American College of Gastroenterology.
