Splenic Metastases
Splenic metastases are deposits of cancer in the spleen that have spread from a primary tumor in another part of the body. Compared with the liver, lungs, and lymph nodes, the spleen is involved by metastatic cancer relatively uncommonly, but the finding is clinically important when it occurs. The most common primary sites include the breast, lung, colon and other gastrointestinal cancers, ovary, melanoma, and others. Splenic metastases usually indicate widespread disease and influence overall cancer staging and treatment planning. Imaging—particularly CT, MRI, and PET/CT—is central to evaluation.
What is it?
The spleen is an organ in the upper left abdomen that filters blood and supports immune function. Splenic metastases are cancer cells that have traveled from a primary tumor elsewhere in the body and formed new deposits within the spleen. Unlike splenic lymphoma, which is a cancer of the lymphatic system that involves the spleen directly, splenic metastases originate from cancers of other organs—such as the breast, lung, gastrointestinal tract, ovary, kidney, prostate, or skin—and spread to the spleen through the bloodstream, the lymphatic system, or by direct extension from neighboring organs.
The spleen is involved by metastatic cancer relatively uncommonly compared with the liver, lungs, and lymph nodes. The reasons for this relative resistance are not entirely understood but may involve unique features of splenic blood flow and immune environment. Even so, splenic metastases do occur, and their incidence appears higher in modern series because of improved imaging and longer survival of patients with advanced cancer.
The most common primary tumors that metastasize to the spleen include cancers of the breast, lung, colon, stomach, pancreas, ovary, and—particularly known for splenic involvement—melanoma. Less commonly, cancers of the kidney, prostate, endometrium, and other organs may spread to the spleen. Lymphoma, leukemia, and other hematologic cancers can involve the spleen but are typically classified separately from metastatic solid tumors. Splenic involvement may occur as part of widespread metastatic disease (which is the most common scenario) or, much less commonly, as an isolated finding in a patient with otherwise localized cancer.
Splenic metastases can present as one or more discrete nodules or masses, diffuse infiltration of the spleen, or—rarely—as a cystic or partially cystic lesion in selected cancer types. Symptoms are often absent or vague. Some patients experience upper left abdominal pain or fullness, early fullness with meals, fatigue, weight loss, fevers, or low blood counts. Many patients have symptoms more attributable to the primary cancer and other sites of disease than to the splenic metastasis itself, and a significant number of splenic metastases are discovered incidentally during staging or follow-up imaging in patients with known cancer.
Diagnosis usually relies on imaging and clinical context. In patients with a known primary cancer, the discovery of one or more new splenic lesions raises strong suspicion for metastatic involvement, especially when other sites of metastatic disease are also present. CT of the abdomen with intravenous contrast is the primary imaging test and provides detailed information about the number, size, and characteristics of splenic lesions, as well as other sites of disease. MRI with contrast can be useful in selected cases, particularly when distinguishing between benign and malignant lesions is difficult. PET/CT is widely used for staging in many cancers and can help characterize splenic involvement and assess overall disease burden. Ultrasound may identify lesions but is generally less sensitive than CT and MRI for detailed characterization.
Image-guided biopsy of the spleen is performed in selected cases, particularly when the diagnosis is uncertain, when no clear primary cancer has been identified, or when the splenic lesion may represent something other than metastasis (such as lymphoma, abscess, or a benign lesion). Splenic biopsy carries some risk of bleeding because the spleen is highly vascular, and the decision is individualized in collaboration with interventional radiology and the oncology team. Blood tests typically include a complete blood count, comprehensive metabolic panel, liver function tests, and tumor markers relevant to the suspected primary cancer.
Important to Know
Management of splenic metastases is directed at the underlying cancer rather than at the spleen itself. The presence of splenic metastases generally indicates advanced or metastatic disease, and treatment is part of an overall strategy that takes into account the type and stage of the primary cancer, sites and burden of metastatic disease, molecular features of the tumor, prior treatments, the patient’s overall health, and personal goals of care.
Systemic therapy is the cornerstone of treatment in most patients with splenic metastases. This may include chemotherapy, targeted therapies, immune checkpoint inhibitors, hormonal therapy, antibody-drug conjugates, and other agents based on the cancer type and molecular profile. Treatment regimens are highly individualized and coordinated by medical oncologists, often as part of multidisciplinary cancer care that may also include radiation oncologists, surgeons, interventional radiologists, pathologists, dietitians, and palliative care providers.
Splenectomy or other local treatments are considered in carefully selected patients. For example, splenectomy may be appropriate in patients with isolated splenic metastasis (no other sites of disease), severe local symptoms that cannot be adequately controlled with other measures, complications such as significant bleeding or rupture of a splenic lesion, or specific tumor types in which removing the spleen may meaningfully affect the overall trajectory. Decisions are individualized and made in collaboration with oncologic surgeons, medical oncologists, and—when relevant—interventional radiologists. Radiation therapy and locoregional treatments are used less commonly for splenic disease but may be considered in specific scenarios.
Patients undergoing total splenectomy require specific attention to infection prevention, including vaccinations against encapsulated bacteria (such as pneumococcal, meningococcal, and Haemophilus influenzae type b vaccines), antibiotic prophylaxis in selected patients, education about prompt evaluation of fevers, and consideration of travel-related risks.
Management of complications and symptoms is an essential part of care. This includes pain management, nutritional support, treatment of fatigue, management of psychological wellbeing, and family-centered care planning. Early integration of palliative care—even alongside active cancer treatment—is associated with improved quality of life and, in some studies, improved outcomes in patients with advanced cancer.
In patients in whom splenic metastases are detected on imaging without a known primary cancer, evaluation focuses on identifying the source. This may include detailed history and examination, additional imaging (such as CT of the chest, mammography, dedicated imaging of specific organs), endoscopy, tumor markers, and—in selected cases—biopsy of an accessible site of disease (which may or may not be the spleen). Tissue diagnosis is essential for accurate identification of the primary tumor and selection of appropriate treatment.
Care is typically coordinated by primary care clinicians and oncology teams. Imaging and laboratory findings are interpreted alongside the patient’s symptoms, examination, and broader clinical context rather than in isolation.
Patients with known splenic metastases benefit from understanding the warning signs of complications and clear plans for when to seek care, particularly with respect to bleeding or rupture risks (which remain relatively uncommon).
Red flag symptoms include sudden severe upper left abdominal pain (especially after trauma to the abdomen), lightheadedness or fainting, rapid heart rate, cool clammy skin or signs of shock, high fever with chills, severe shortness of breath, severe weakness or signs of significant bleeding, sudden severe vomiting with abdominal pain, or rapid worsening of overall condition. These warrant prompt or urgent medical evaluation, as they may indicate splenic rupture, hemorrhage, severe infection, or other serious complications.