What are the differential diagnoses for multiple splenic space‑occupying lesions in a 64‑year‑old woman?

Differential Diagnoses for Multiple Splenic Space-Occupying Lesions in a 64-Year-Old Woman

In a 64-year-old woman with multiple splenic lesions, the primary differentials are metastatic disease (especially from breast, lung, ovarian, colorectal primaries, or melanoma), lymphoma, infectious processes (abscesses, fungal microabscesses), splenic infarction, and vascular neoplasms, with the clinical context and imaging characteristics being critical for narrowing the diagnosis.

Malignant Etiologies

Metastatic Disease

• Metastases to the spleen are rare but increasing in detection due to improved imaging, typically occurring in the context of multivisceral disseminated cancer 1
• The most common primary sources are breast, lung, colorectal, and ovarian carcinomas, and melanoma 2, 1
• Splenic metastases can present as solitary or multiple lesions, with colorectal and ovarian carcinomas being the most common sources of solitary splenic metastasis 1
• Any invasion of surrounding splenic parenchyma suggests a more aggressive or malignant process 3

Lymphoma

• Lymphoma represents one of the most common neoplastic disorders of the spleen and must be differentiated from other splenic masses 3
• Multiple splenic lesions can occur with both Hodgkin's and non-Hodgkin's lymphoma, including post-transplant lymphoproliferative disorders 4
• The spleen may be involved as part of systemic lymphoma or as a primary splenic lymphoma

Infectious Etiologies

Splenic Abscesses

• In immunocompromised patients, multiple small splenic lesions usually represent disseminated fungal disease and microabscesses 2
• Splenic abscess develops through bacteremic seeding of bland infarction or direct seeding by infected emboli 4
• Viridans streptococci and S. aureus each account for 40% of splenic abscess cases, with enterococci accounting for 15% 4
• CT and MRI have 90-95% sensitivity and specificity for diagnosing splenic abscess, appearing as single or multiple contrast-enhancing cystic lesions 4, 5
• Persistent or recurrent bacteremia, persistent fever, or ongoing sepsis suggest splenic abscess rather than bland infarction 4, 6

Vascular Etiologies

Splenic Infarction

• Splenic infarcts appear as peripheral wedge-shaped low-density areas on CT, distinct from the contrast-enhancing cystic appearance of abscesses 4, 5
• Multiple infarcts can occur with embolic sources, portal hypertension, or pancreatitis 2
• Infarcts generally show clinical and radiographic improvement during appropriate antibiotic therapy, unlike abscesses 4

Primary Vascular Neoplasms

• Primary vascular neoplasms constitute the majority of nonhematolymphoid splenic tumors 3
• Benign lesions include hemangioma (most common echogenic solid or complex cystic mass in asymptomatic patients), hamartoma, and lymphangioma 3
• Malignant vascular neoplasm is angiosarcoma, which can present with multiple lesions 3
• Hemangiomas may have complex imaging appearance making differentiation from malignant disease difficult 3

Benign Mimickers

Splenosis

• Splenosis should be considered in any patient with history of splenic trauma or surgery presenting with multiple abdominal/pelvic nodules 7, 8
• These ectopic splenic implants can mimic metastatic disease, peritoneal carcinomatosis, lymphoma, or other malignancies on imaging 8
• Splenosis typically occurs in the absence of systemic symptoms and can avoid unnecessary biopsy or treatment 8

Diagnostic Algorithm

Initial Imaging Approach

• CT scan with IV contrast is the preferred diagnostic modality, with 90-95% sensitivity and specificity for splenic pathology 5, 6
• CT can differentiate between solid and cystic lesions, identify characteristic patterns (wedge-shaped infarcts vs. contrast-enhancing abscesses) 4, 5
• MRI provides equivalent diagnostic accuracy to CT (90-95% sensitivity/specificity) for differentiating infarction from abscess 5

Clinical Context Assessment

• Evaluate for immunocompromised state (fungal microabscesses are the primary consideration) 2
• Assess for history of splenic trauma or surgery (consider splenosis) 7, 8
• Screen for known primary malignancy (metastases occur in context of disseminated disease) 1
• Look for signs of endocarditis (splenic abscess complicates 5% of splenic infarctions in left-sided IE) 4
• Check for fever, bacteremia, or sepsis (suggests abscess rather than bland infarction) 4, 6

Tissue Diagnosis

• Fine-needle aspiration or percutaneous biopsy can establish diagnosis and may replace splenectomy for solitary lesions 1
• Splenectomy may be required for definitive evaluation of masses with atypical features 3
• For suspected lymphoma, tissue diagnosis with immunohistochemistry is essential 4

Critical Pitfalls to Avoid

• Never rely on clinical splenomegaly alone, as it is present in only 30% of splenic pathology cases 6
• Do not assume all multiple splenic lesions are metastatic without considering infectious etiologies, especially in immunocompromised patients 2
• Differentiate splenic abscess from bland infarction carefully, as abscesses respond poorly to antibiotics alone and require splenectomy 4, 5
• Consider splenosis before pursuing aggressive treatment in patients with prior splenic trauma/surgery to avoid unnecessary interventions 8