What is a common physical finding in patients with Myeloproliferative Neoplasms (MPNs)?

Splenomegaly is the Most Common Physical Finding in Myeloproliferative Neoplasms

Splenomegaly (enlarged spleen) is the most common physical finding in patients with myeloproliferative neoplasms (MPNs). 1

Why Splenomegaly Occurs in MPNs

Splenomegaly in MPNs results from extramedullary hematopoiesis (blood cell production outside the bone marrow) and is a hallmark physical finding across the spectrum of MPNs:

• In primary myelofibrosis (PMF), splenomegaly is often marked and progressive
• In polycythemia vera (PV), splenomegaly may be less pronounced initially but can progress
• In essential thrombocythemia (ET), splenomegaly is typically milder but still present in many cases

Clinical Significance of Splenomegaly

Splenomegaly has important diagnostic and clinical implications in MPNs:

1. Diagnostic value: Palpable splenomegaly is a minor criterion for both pre-fibrotic/early primary myelofibrosis and overt primary myelofibrosis diagnosis 1

2. Symptom burden: Marked hepatosplenomegaly is often accompanied by:

   • Early satiety
   • Severe abdominal discomfort
   • Changes in bowel habits
   • Painful splenic infarcts
   • Portal hypertension leading to ascites and variceal bleeding
   • Compromised mobility and movement
   • Cachexia 1

3. Treatment indicator: Symptomatic or progressive splenomegaly is an indication for initiating cytoreductive therapy even in otherwise low-risk MPN patients 1

Assessment of Splenomegaly

While clinical assessment by physical examination (palpation) is standard practice, it has limitations:

• Physical examination is subjective and may miss mild splenomegaly
• More objective measurements include:
  • Ultrasonography (US)
  • Magnetic resonance imaging (MRI)
  • Computed tomography (CT)

Recent evidence shows a strong correlation between ultrasonography and MRI for spleen volume assessment (correlation coefficient r = 0.96), supporting the use of ultrasonography as a practical clinical tool 2.

Management of Splenomegaly in MPNs

Treatment of symptomatic splenomegaly includes:

1. First-line therapy: Hydroxyurea is the drug of choice, with reduction of spleen volume occurring in approximately 40% of patients 1

2. Second-line options for hydroxyurea-refractory disease:

   • Intravenous cladribine
   • Oral melphalan
   • Oral busulfan
   • JAK inhibitors (ruxolitinib) 3

3. Radiation therapy: Low-dose splenic irradiation can provide temporary symptomatic relief (typically lasting 3-6 months) 1

4. Splenectomy: Reserved for drug-refractory cases with:

   • Symptomatic portal hypertension
   • Painful splenomegaly
   • Severe cachexia
   • Transfusion-dependent anemia

   However, splenectomy carries significant risks:

   • 5-10% perioperative mortality
   • ~50% complication rate (bleeding, thrombosis, infections, accelerated hepatomegaly) 1

Comparison with Other Physical Findings

While the other options mentioned in the question (back pain, headaches, and ecchymosis) may occur in MPN patients, they are not as consistently present as splenomegaly:

• Back pain: Can occur but is not a defining physical finding
• Headaches: May be present, particularly in patients with elevated hematocrit, but less common than splenomegaly
• Ecchymosis: May occur in patients with platelet dysfunction or extreme thrombocytosis, but is not a characteristic finding across all MPNs

Therefore, among the options presented, splenomegaly is clearly the most common physical finding in patients with MPNs.