Immune Thrombocytopenia and Importance of Bone Marrow Examination

Introduction:

Adults with immuno-thrombocytopenia (ITP) may undergo bone marrow exams to rule out conditions like leukemia, though these typically present with additional symptoms. No definitive blood test distinguishes between bone marrow issues and platelet destruction. ASH guidelines in 1996 suggested uncertainty about the necessity of bone marrow exams in typical ITP cases. Research on finding unexpected diseases like leukemia in ITP through bone marrow tests is limited. This study aims to assess this issue, considering the discomfort and cost of bone marrow exams. If proven unnecessary for straightforward ITP cases, these exams could be avoided.

What Is Immune Thrombocytopenia?

Immune thrombocytopenia (ITP) is when the blood does not clot properly because of a low platelet count. Platelets are small blood cells produced in the bone marrow that help form clots to stop bleeding when injured. With a low platelet count, one may have difficulty stopping bleeding. ITP can be short-term (acute), often lasting less than six months, commonly seen in children. Long-term (chronic) ITP, lasting six months or more, mostly affects adults but can also occur in some teens and children, with women being affected more than men.

Why Do Doctors Often Perform Bone Marrow Aspirations in Adults Initially Suspected of Having Immune Thrombocytopenia?

• Doctors worry about missing leukemia or aplastic anemia in adults initially thought to have immune thrombocytopenia (ITP).

• In a study, patients with low platelet counts, normal blood smears, and normal clotting studies did not have leukemia.

• Other studies on children and adults with similar symptoms also showed that leukemia was absent in typical ITP cases.

• Recent research suggests that a bone marrow examination may be unnecessary for patients with clinical and lab features consistent with ITP.

• Studies found that typical ITP features did not coexist with leukemia, supporting the idea that a bone marrow test may not be needed.

• Despite efforts, there's no reliable serologic test for ITP, and current tests have limitations in sensitivity and specificity.

• The study acknowledges limitations such as a small sample size and the need for further research in specific age groups.

• Routine bone marrow exams may not be necessary for typical ITP cases; instead, they could be reserved for cases with atypical features or poor treatment response.

• Clinical assessment and blood smear examination are crucial for diagnosing ITP, and a careful approach is recommended for bone marrow tests.

What Characterizes ITP in Terms of Platelet Counts and Bone Marrow Changes?

• ITP involves low platelet counts due to their destruction in the body and changes in the bone marrow.

• Changes in megakaryocytes (cells involved in platelet production) are common, such as a shift to younger forms.

Bone Marrow Role in ITP:

• The importance of bone marrow in ITP diagnosis is uncertain when a thorough clinical history, physical exam, and blood smear are conducted.

• A complete blood count and peripheral blood smear are crucial for diagnosing ITP.

• Studies in children and adults show that bone marrow examination doesn't alter the diagnosis when isolated thrombocytopenia is present.

• A study on children suggested a minimal risk of missing leukemia diagnosis (less than one percent).

• A study explored different strategies for managing children with thrombocytopenia and concluded that initial bone marrow examination didn't significantly change overall outcomes.

• A study on adult ITP patients found low sensitivity (24 %) and high specificity (90 %) for bone marrow examinations.

• In contrast, no child with isolated thrombocytopenia had leukemia in a study on acute lymphoblastic leukemia.

• Earlier cases misdiagnosed as ITP led to a policy of routine bone marrow exams unless immunoglobulin therapy was planned.

• Differences exist in bone marrow examination practices among specialists globally.

Organomegaly in ITP:

• Organ enlargement, particularly the spleen, can occur in ITP patients.

• The study is retrospective, with limitations like selection bias and potential incomplete documentation.

• Organomegaly prevalence in patients aged 60 or older is low in the study.

How Bone Marrow Examination Is Done and Its Relevance in ITP Prognosis?

• Experienced pathologists faced difficulties identifying immune thrombocytopenia (ITP) in patients through bone marrow examinations.

• Patients with severe ITP displayed unique bone marrow characteristics, challenging the belief that bone marrow tests aid ITP diagnosis and indicate variability in ITP appearances.

• Data suggested that many ITP patients had normal bone marrow, aligning with doctors' expectations and supporting that routine bone marrow tests may not be necessary for typical ITP cases.

• Previous studies on ITP bone marrow features yielded conflicting results, but our controlled study found that severe ITP bone marrow resembled that of unaffected individuals, except for a specific subgroup.

Diagnostic Purpose of Bone Marrow Examinations:

• While bone marrow examinations typically aim to rule out blood disorders like leukemia or myelodysplastic syndrome, they were rarely informative in isolated low platelet count cases, as evidenced by our large-scale study.

• The study suggested that ITP may involve different patient groups with unique bone marrow features and potential variations in the causes of low platelet count.

• Approximately 20 % of patients in our study exhibited increased megakaryocytes, indicating a disorder driven by peripheral platelet destruction with compensatory bone marrow response, which correlates with the observation that a similar proportion of ITP patients do not respond to certain medications.

• Exploring bone marrow beyond basic features may aid in distinguishing between platelet destruction and underproduction, guiding personalized treatment approaches for ITP.

• The study's strengths included selecting clinically similar ITP patients, rigorous pathological review, and advanced statistical modeling.

• Limitations included the potential for studied ITP patients having more severe disease and the control group not representing typical patients confused with ITP.

Emphasis on Limited Use of Bone Marrow Examination: Despite limitations, our study strongly emphasizes that routine bone marrow examination is not useful for diagnosing ITP in typical cases, supporting recent recommendations against its routine use.

Future Research: Future research should explore the link between subtle bone marrow changes and outcomes in ITP patients.

Conclusion:

When someone shows symptoms of immune thrombocytopenia (ITP), a condition with low platelet levels leading to bleeding and bruising, it's generally advised not to use a bone marrow biopsy to confirm the diagnosis. This aligns with the American Society of Hematology recommendations and many international guidelines. However, in Denmark, their ITP guidelines suggest considering a bone marrow biopsy for most suspected ITP cases, except for clear cases in young patients. To resolve this difference, researchers in Scandinavia wanted to find out if using a bone marrow biopsy in ITP cases is necessary.