A 34-year-old man comes to the clinic due to a 2-week history of right upper quadrant abdo… — USMLE Step 2 CK

A $34$ -year-old man comes to the clinic due to a $2$ -week history of right upper quadrant abdominal pain, fever, and significant fatigue. He returned from a $6$ -month backpacking trip across Southeast Asia and India approximately $1$ month ago. During his trip, he experienced an episode of severe, bloody diarrhea that resolved after $5$ days with over-the-counter oral rehydration. His temperature is $38.7^\circ\text{C}$ ( $101.7^\circ\text{F}$ ), pulse is $102/\text{min}$ , and blood pressure is $118/76\text{ mm Hg}$ . Physical examination reveals a moderately enlarged liver with marked point tenderness to palpation in the right subcostal region. There is no scleral icterus.

Laboratory studies show:

Test	Result
Leukocyte count	$14,500/\text{mm}^3$
Neutrophils	$82\%$
Eosinophils	$2\%$
Aspartate aminotransferase (AST)	$68\text{ U/L}$
Alanine aminotransferase (ALT)	$75\text{ U/L}$
Alkaline phosphatase	$310\text{ U/L}$
Total bilirubin	$1.1\text{ mg/dL}$

An abdominal ultrasound reveals a solitary, $7\text{-cm}$ , round, hypoechoic cystic lesion in the right hepatic lobe with no internal septations.

Which of the following is the most appropriate next step in management?

Initiation of oral metronidazole therapyCevap
B
CT-guided percutaneous aspiration and drainage
C
Intravenous piperacillin-tazobactam administration
D
Initiation of oral albendazole therapy
E
Endoscopic retrograde cholangiopancreatography

Cevap

The most appropriate next step is the initiation of oral metronidazole therapy.

The clinical presentation of a young man with recent travel to an endemic area, a preceding episode of bloody dysentery, fever, right upper quadrant pain, and a solitary hypoechoic mass in the right hepatic lobe on ultrasound is classic for an amebic liver abscess caused by Entamoeba histolytica. The diagnosis is definitively confirmed with serologic testing (e.g., E. histolytica IgG antibodies), but empiric medical therapy with oral metronidazole should be initiated immediately when clinical suspicion is high. Following the tissue amebicide (metronidazole), a luminal agent (such as paromomycin or intraluminal iodoquinol) must be given to eradicate intestinal colonization and prevent relapse. Unlike pyogenic liver abscesses, percutaneous drainage is not routinely required and is reserved for large abscesses at high risk of rupture (e.g., left lobe abscesses near the pericardium) or when there is no clinical improvement after 3 to 5 days of medical therapy.

Adım Adım Çözüm

Analyze the patient's epidemiologic risk factors and symptom timeline.

The patient is a young male with recent travel to endemic regions (India, Southeast Asia) and a recent history of bloody dysentery, now presenting with fever and right upper quadrant pain.

Identifying travel history and preceding infections helps narrow the differential diagnosis for hepatic lesions, pointing strongly toward a protozoal etiology.

Evaluate the laboratory and imaging findings.

Labs show leukocytosis and an isolated elevated alkaline phosphatase without jaundice. Ultrasound reveals a solitary, hypoechoic cystic mass in the right hepatic lobe.

This classic triad (epidemiology, clinical presentation, solitary right-lobe hypoechoic mass) is highly characteristic of an amebic liver abscess caused by Entamoeba histolytica.

Determine the standard of care for the suspected diagnosis.

Uncomplicated amebic liver abscesses are treated medically with a tissue amebicide (metronidazole) followed by a luminal agent (paromomycin) to eradicate intestinal colonization.

Unlike pyogenic abscesses, percutaneous drainage is not routinely indicated for amebic abscesses unless rupture is imminent or medical therapy fails.

Anahtar Kavram

Diagnosis and management of amebic liver abscesses versus other hepatic cystic lesions.

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Cevap

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