An unusual case of isolated serum γ-glutamyl transferase elevation: slight abnormality also should not be taken lightly.

A 75-year-old man was admitted to our hospital for isolated serum γ-glutamyl transpeptidase (GGT, 147 U/L) elevation, with fluctuation in the past 2 years ([Fig. 1]). His alanine aminotransferase, glutamic transaminase, bilirubin level, and tumor markers were all in normal range. He had no symptoms, except for mild soreness in the right waist for 2 months. Magnetic resonance imaging (MRI) revealed a low signal in T2 W with dilation of the common bile duct (CBD) to 12 mm and enlargement of the gallbladder ([Fig. 2]). Hence, endoscopic ultrasound (EUS) was performed for a definite diagnosis. The major papilla was small with a normal surface ([Fig. 3]). In the distal CBD, a hypoechoic nodule (13.1 × 7.2 mm) was found wriggling along with the sphincter contraction ([Fig. 4 a]). Contrast-enhanced EUS showed the enhancement of the lesion, but the degree was weaker than the peripheral pancreas ([Fig. 4 b], [Video 1]).