Riedel Fight Song: a case report of riedel lobe presumed to be hepatomegaly

Abstract

Riedel lobe is a liver variation occasionally confused with an abdominal mass or hepatomegaly. The clinical infrequency of this condition and its resemblance to more serious conditions can initiate unnecessary workup or surgery if not considered early. An otherwise healthy, 14-year-old girl presented to the gastroenterology (GI) clinic for follow-up to an emergency room (ER) visit with a 3-day history of right upper quadrant (RUQ) pain. She reported during the first 24 hours a sharp, constant, non-radiating pain increased from 2 to 6/10, improved with ice and ibuprofen, and aggravated with activity and laying on her right side. Physical exam was significant for tenderness in the RUQ and liver edge palpated 2 finger breadths below the subcostal margin anteriorly and laterally to the iliac crest. Pain was reproduced by rotation of her trunk. Laboratory findings were unremarkable. Before further testing, the pediatric radiologist consulted identified the hepatomegaly as a “Riedel lobe, elongated and functional.” Further history elicited a social wrestling match the night prior to onset; repeat physical exam suggested a strain in the right upper rectus abdominis muscle. Relative rest, ice and ibuprofen for pain were prescribed and patient education was conducted. First reported in 1888 when seven cases were confirmed by surgical exploration, the incidence of Riedel lobe is now known to occur in approximately 25% of 20-45 year-olds and 60% of 45-65 year-olds, with female: male ratio of 3:1. Potential morbidities include lobar torsion, mass effect induced obstruction, interference with laparoscopic surgical procedures and unnecessary imaging. Clues from the history and physical exam can help distinguish this variant from other liver pathology. Physician awareness, the use of Doppler ultrasonography, and pediatric radiology consult should be considered before the use of more intensely radiating imaging.