In a 29-year-old man with known splenomegaly presenting with dull pressure under the left shoulder blade, what are the possible causes and recommended evaluation?

Dull Pressure Under Left Shoulder Blade in 29-Year-Old Male with Splenomegaly

This patient requires urgent CT abdomen and pelvis with IV contrast to evaluate for splenic infarction, abscess, or rupture, as left shoulder pain (Kehr's sign) in the setting of known splenomegaly is a red flag for serious splenic complications that can be life-threatening.

Clinical Significance and Differential Diagnosis

The combination of left shoulder blade pain and known splenomegaly is concerning for several potentially life-threatening conditions. Pain in the back, left flank, or left upper quadrant—including referred pain to the left shoulder—may be associated with either splenic infarction or abscess 1. This referred pain pattern (Kehr's sign) occurs due to diaphragmatic irritation from splenic pathology.

Key Diagnostic Considerations:

Splenic infarction is the most common serious complication in patients with splenomegaly. While often asymptomatic when detected by imaging, symptomatic infarction can present with:

• Back, left flank, or left shoulder pain
• Risk of progression to splenic abscess (occurs in ~5% of infarctions) 1
• Potential for splenic rupture with hemorrhage (rare but catastrophic) 1

Splenic abscess should be suspected if there is:

• Persistent or recurrent fever
• Ongoing sepsis
• Progressive pain
• History of endocarditis or systemic infection 1

Atraumatic splenic rupture is rare but can occur with:

• Massive splenomegaly from any cause
• Infectious mononucleosis (0.1-0.5% of cases) 2
• Hematologic disorders 3

Immediate Diagnostic Approach

First-Line Imaging: CT Abdomen and Pelvis with IV Contrast

CT with IV contrast is the gold standard for evaluating splenic complications, with 90-95% sensitivity and specificity for diagnosing splenic abscess 1. The 2025 ACR Appropriateness Criteria strongly support this as initial imaging for acute left upper quadrant pain with suspected splenomegaly 4.

CT findings that differentiate conditions:

• Splenic infarction: Peripheral, low-density, wedge-shaped areas
• Splenic abscess: Single or multiple contrast-enhancing cystic lesions
• Rupture: Free fluid (hemoperitoneum), splenic laceration 1, 2

Alternative/Complementary Imaging:

Ultrasound can be used as an initial screening tool if CT is not immediately available, though it has only 18% sensitivity for detecting splenic infarcts compared to CT 4. However, US is useful for:

• Confirming splenomegaly
• Detecting perisplenic fluid collections
• Serial monitoring 4

MRI without and with IV contrast is an alternative with similar diagnostic accuracy to CT (90-95% sensitivity) but is less practical in the acute setting 4.

Clinical Assessment Priorities

While imaging is being arranged, assess for:

Hemodynamic stability:

• Vital signs (hypotension, tachycardia suggest rupture or hemorrhage)
• Signs of shock (shortened capillary refill time, altered mental status) 2

Signs of infection:

• Fever, chills
• Persistent bacteremia
• Signs of sepsis 1

Hematologic parameters:

• Complete blood count (sudden drop in hemoglobin/hematocrit suggests rupture or sequestration) 2, 3
• Coagulation studies
• Blood cultures if febrile 1

Underlying etiology of splenomegaly:

• Hematologic disorders (sickle cell, lymphoproliferative disorders)
• Infectious causes (EBV, endocarditis)
• Portal hypertension
• Malignancy 4, 5

Management Algorithm Based on Findings

If Splenic Infarction Confirmed:

• Monitor clinically and radiographically
• Appropriate antibiotics if underlying infection
• Serial imaging to ensure no progression to abscess 1

If Splenic Abscess Confirmed:

Definitive treatment is splenectomy with appropriate antibiotics, which should be performed immediately unless urgent valve surgery is also planned (in endocarditis cases) 1. Percutaneous drainage may be considered only for poor surgical candidates 1.

If Splenic Rupture Confirmed:

• Immediate surgical consultation
• Hemodynamic resuscitation
• Expeditious splenectomy if unstable 2, 3

Critical Pitfalls to Avoid

1. Do not rely on clinical splenomegaly alone: Physical examination splenomegaly is present in only 30% of infective endocarditis cases and is not reliable for detecting infarction or abscess 1

2. Do not delay imaging: Differentiation between bland infarction and abscess is difficult clinically but critical for management—imaging is mandatory 1

3. Do not assume benign etiology: In a 29-year-old with known splenomegaly, left shoulder pain should never be dismissed as musculoskeletal without excluding splenic pathology 4

4. Post-splenectomy considerations: If splenectomy is performed, ensure vaccination against encapsulated bacteria (S. pneumoniae, H. influenzae, N. meningitidis) starting 14 days post-operatively 6

The urgency of this evaluation cannot be overstated—splenic rupture carries significant mortality risk, and splenic abscess responds poorly to antibiotics alone, requiring surgical intervention 1, 2.