Overview

What is evans syndrome?

Evans Syndrome (ES) is a rare and complex autoimmune disease that causes the immune system to target and attack its own blood cells (cytopenia).¹ The disease was named after Dr Robert Evans, who first described it in the 1950s.⁸ It is a combination of autoimmune blood conditions, which usually involve:^2,3

• Low Red blood cells (leading to autoimmune haemolytic anaemia [AIHA])
• Low Platelet count (causing easy bruising or bleeding or immune thrombocytopenia (ITP), and sometimes
• Low White blood cell count (leading to more frequent infections or autoimmune neutropenia [AIN])

Evans syndrome frequently results in overlapping symptoms as it affects multiple blood cell lines, which require careful and rigorous testing to rule out other causes. Bone marrow evaluation is one of the most important studies in this procedure. Bone marrow testing is frequently taken into consideration when a patient exhibits cytopenia suggestive of Evans syndrome. ¹  The goal is to rule out other possible causes of cytopenia, such as malignancy or bone marrow failure syndromes, rather than to confirm the diagnosis of ES itself.⁴

Causes of evans syndrome

Evans syndrome can develop as a primary (idiopathic) disorder or as a secondary condition linked to other diseases. In primary Evans syndrome, which is more common in children, there is no identifiable cause. Instead, the immune system produces autoantibodies that target red blood cells, platelets, and occasionally white blood cells. It is believed that this may result from a combination of genetic predisposition and environmental triggers, such as infections

Secondary Evans syndrome occurs when autoimmune blood cell destruction begins with other conditions. The most common are autoimmune diseases such as systemic lupus erythematosus, immune deficiencies like autoimmune lymphoproliferative syndrome (ALPS) or common variable immunodeficiency (CVID), and haematological cancers, including chronic lymphocytic leukaemia (CLL) or lymphoma. Viral infections such as Epstein–Barr virus (EBV), cytomegalovirus (CMV), HIV, and hepatitis C may also play a role in triggering or worsening Evans syndrome ^1,6,7,12

Symptoms of evans syndrome in adults

Adults with Evans syndrome often present with a chronic or relapsing-remitting course. Symptoms can vary depending on which blood cells are most affected at a given time.

When red blood cells are destroyed (anaemia) relapse:^9,11

• Tiredness and fatigue
• Pale skin
• Dizziness, light-headedness, or fainting
• Shortness of breath on exertion
• Rapid or irregular heartbeat

When platelets are destroyed (thrombocytopenia):

• Easy bruising
• Small purple or red skin spots (petechiae)
• Nosebleeds or gum bleeding
• Heavy or prolonged menstrual bleeding

When white blood cells are destroyed (neutropenia):

• Frequent infections such as chest infections, urinary tract infections, or skin infections
• Fevers and night sweats
• Slow wound healing

In adults, Evans syndrome may also be associated with, such as lupus or rheumatoid arthritis, or with blood cancers like lymphoma and chronic lymphocytic leukaemia⁹

Symptoms of evans syndrome in children

In children, Evans syndrome usually begins more suddenly, often triggered by an infection. The cause can be unpredictable, with some children experiencing one episode and relapsing.^5,9,11

Anaemia symptoms

• Irritability and mood changes
• Unusual tiredness
• Pale skin or mucous membranes
• Jaundice (yellowing of the skin and eyes due to red blood cell breakdown)

Thrombocytopenia symptoms

• Frequent nosebleeds
• Easy bruising after minor bumps
• Gum bleeding during brushing
• Prolonged bleeding after cuts or minor surgery

Neutropenia symptoms

• Recurrent ear infections, sore throats, or chest infections
• High fevers
• Delayed recovery from common illnesses

Chronic Evans syndrome in children can also affect growth and daily activities. Importantly, in children, Evans syndrome may be associated with an inherited.

Why is bone marrow evaluation performed?

Bone marrow is the soft, spongy tissue inside bones where all blood cells are produced. In Evans syndrome, a bone marrow evaluation helps answer two vital questions.¹⁰

• Is the marrow producing enough blood cells?

If the marrow is working normally, this suggests that low blood counts are due to immune destruction outside the marrow.

• Is there another underlying disease?

Conditions such as leukaemia, lymphoma, aplastic anaemia, or bone marrow failure syndromes can mimic Evans syndrome. A marrow examination helps rule these out.⁴

Indications for bone marrow examination in suspected ES

Bone marrow assessment is generally considered in the following scenarios:⁹

1. Atypical presentations: Unexplained pancytopenia, reticulocytopenia, or systemic symptoms (fever, lymphadenopathy, hepatosplenomegaly)
2. Refractory or relapsing disease: If cytopenias fail to respond to first-line therapy (steroids, IVIG)
3. Before invasive or immunosuppressive treatments: For example, prior to splenectomy or chemotherapy
4. Exclusion of secondary causes: Malignancies such as leukaemia, lymphoma, or myeloma; marrow infiltration by metastatic disease; or congenital marrow failure syndromes

What bone marrow evaluation involves

Bone marrow examination typically includes:

• Aspiration: Obtaining a liquid sample to examine cell morphology and counts
• Trephine biopsy: Obtaining a core of bone marrow tissue to assess architecture, cellularity, and infiltration

These procedures allow pathologists to determine whether the bone marrow is:

• Hypocellular – low production of blood cells, suggesting marrow failure
• Normocellular or hypercellular – normal or increased cell production, often reactive to peripheral destruction

Summary

Bone marrow evaluation in suspected Evans syndrome is primarily an exclusion tool. It reassures clinicians when marrow function is normal and helps detect dangerous alternative diagnoses when it is not. In Evans syndrome, the marrow typically appears hyperactive, reflecting the immune system’s destruction of blood cells in circulation rather than failure of production.

By distinguishing between these two mechanisms, bone marrow evaluation provides critical information that guides treatment decisions and ensures accurate diagnosis.

FAQs

Does bone marrow evaluation confirm Evans syndrome?

No. Diagnosis is based on blood tests and clinical findings. Bone marrow helps rule out other diseases.

What does the bone marrow look like in evans syndrome?

Typically hypercellular, with an excess of red cell precursors and megakaryocytes.

Why is the test important in adults?

To exclude blood cancers and autoimmune-related marrow disorders.

Why is it important in children?

To differentiate Evans syndrome from congenital marrow problems and inherited immune disorders.

What causes evans syndrome?

It can be primary, often seen in children, where the cause is unknown but thought to involve abnormal immune regulation. In adults, it is often secondary to autoimmune diseases like lupus, immune deficiencies such as ALPS or CVID, and blood cancers

Is the procedure painful?

It is generally safe and performed with local anaesthesia. Some soreness is expected, but serious risks are rare.