Review Question - QID 109692

A 62-year-old man presents to his primary care physician. He was brought in by his daughter as he has refused to see a physician for the past 10 years. The patient has been having worsening abdominal pain. He claims that it was mild initially but has gotten worse over the past week. The patient has been eating lots of vegetables recently to help with his pain. The patient has a past medical history of constipation and a 50-pack-year smoking history. He is not currently taking any medications. On review of systems, the patient endorses trouble defecating and blood that coats his stool. His temperature is 99.5°F (37.5°C), blood pressure is 197/128 mmHg, pulse is 100/min, respirations are 17/min, and oxygen saturation is 98% on room air. On abdominal exam, the patient complains of right upper quadrant tenderness and a palpable liver edge that extends 4 cm beneath the costal margin. The patient states that he feels pain when pressure is applied and then suddenly released to the right upper quadrant. The patient's skin has a yellow hue to it. HEENT exam is notable for poor dentition, normal sclera, and normal extraocular movements. There are no palpable lymph nodes. Laboratory studies are ordered as seen below:

Hemoglobin: 9 g/dL
Hematocrit: 30%
Leukocyte count: 7,500/mm^3 with normal differential
Platelet count: 199,000/mm^3

Serum:
Na+: 140 mEq/L
Cl-: 101 mEq/L
K+: 4.0 mEq/L
HCO3-: 23 mEq/L
BUN: 29 mg/dL
Glucose: 197 mg/dL
Creatinine: 1.4 mg/dL
Ca2+: 10.2 mg/dL
Total bilirubin: 1.1 mg/dL
AST: 150 U/L
ALT: 112 U/L

Which of the following is the most likely diagnosis?