A 58 years-old man without comorbidities presented 3 episodes of acalculous cholecystitis since 2018. Nowadays, he actually is assymptomatic, although presents a focal thickening of the gallbladder fundus in CT and MRI without gallstones. There is no distant dissemination. He also presents seric level of ca 19,9 slightly high (67,5 ng/dl) and normal CEA.
What is your diagnosis?
What is the best approach?