From the Guidelines
The most likely test to confirm the diagnosis in this case is a bone marrow biopsy (option D). This 6-year-old boy with Down syndrome presents with concerning symptoms including prolonged fever, fatigue, weakness, diffuse limb pain, and cervical lymphadenopathy. Children with Down syndrome have a significantly increased risk of developing acute leukemia, particularly acute lymphoblastic leukemia (ALL) 1. The constellation of symptoms described - fever, fatigue, bone pain, and lymphadenopathy - are classic presentations of leukemia, as seen in patients with diffuse large B-cell lymphoma (DLBCL) and Burkitt lymphoma (BL) 1. While a peripheral blood smear might show abnormal cells, a bone marrow biopsy is the gold standard for diagnosing leukemia as it allows for detailed examination of the bone marrow cellular composition, cytogenetic analysis, and immunophenotyping. This is essential for confirming the diagnosis, determining the specific type of leukemia, and guiding appropriate treatment.
Some key points to consider in this case include:
- The patient's history of Down syndrome, which increases the risk of developing leukemia 1
- The presence of symptoms such as fever, fatigue, and bone pain, which are common in leukemia 1
- The importance of a bone marrow biopsy in diagnosing leukemia and guiding treatment
- The need to rule out other potential causes of the patient's symptoms, such as infection or other hematologic disorders
The other listed options would not be as definitive for diagnosing leukemia in this clinical scenario. For example, a monospot test (option A) is used to diagnose infectious mononucleosis, which may present with similar symptoms but is a distinct clinical entity. Blood culture (option B) may be useful in identifying a bacterial infection, but would not confirm a diagnosis of leukemia. Echocardiography (option C) may be relevant given the patient's history of congenital heart disease, but is not directly related to the diagnosis of leukemia. Serum protein electrophoresis (option F) may be useful in diagnosing certain hematologic disorders, but is not the most appropriate test in this case. A peripheral blood smear (option E) may show abnormal cells, but a bone marrow biopsy is necessary to confirm the diagnosis and guide treatment.
From the Research
Diagnosis of Leukemia in a Child with Down Syndrome
The child's symptoms, including mild fever, generalized weakness, fatigue, and diffuse pain in the legs and arms, along with a history of Down syndrome and congenital atrial septal defect, suggest a possible diagnosis of leukemia.
- The child's enlarged cervical lymph nodes and laboratory results support this suspicion.
- Given the child's history of Down syndrome, which is a known risk factor for leukemia 2, 3, a diagnostic test that can confirm the presence of leukemia is necessary.
Diagnostic Options
The following options are available to confirm the diagnosis:
- A bone marrow biopsy is a crucial diagnostic tool for leukemia, as it allows for the examination of bone marrow cells and the detection of any abnormalities 4, 5.
- A peripheral blood smear can also be used to detect abnormal cells, but it may not be as sensitive as a bone marrow biopsy.
- Other options, such as monospot, blood culture, echocardiography, and serum protein electrophoresis, are not directly relevant to the diagnosis of leukemia.
Most Likely Diagnostic Test
Based on the evidence, a bone marrow biopsy is the most likely test to confirm the diagnosis of leukemia in this child 4, 5. This test can provide a definitive diagnosis and help guide treatment decisions. Additionally, the child's history of Down syndrome and congenital heart disease increases the risk of leukemia, making a bone marrow biopsy a crucial diagnostic tool 6, 2, 3.