Differential Diagnosis for Bilateral Leg and Back Pain in an 8-year-old Boy with Sickle Cell Disease
- Single most likely diagnosis:
- Sickle cell crisis: The patient's history of sickle cell disease, multiple prior hospitalizations for similar pain episodes, and current symptoms of bilateral leg and back pain are highly suggestive of a sickle cell crisis. The lack of relief with pain management and the presence of conjunctival pallor and tachycardia further support this diagnosis.
- Other Likely diagnoses:
- Osteomyelitis: Although less likely, osteomyelitis is a possible cause of bone pain in a patient with sickle cell disease. The absence of erythema, swelling, or fever makes this diagnosis less likely, but it should still be considered.
- Septic arthritis: Similar to osteomyelitis, septic arthritis is a potential cause of joint pain in a patient with sickle cell disease. However, the lack of joint swelling, erythema, or significant fever reduces the likelihood of this diagnosis.
- Do Not Miss diagnoses:
- Infection (e.g., pneumonia, urinary tract infection): Patients with sickle cell disease are at increased risk of infections, which can trigger a sickle cell crisis. Although the patient's temperature is normal, it is essential to consider and rule out infections, as they can be life-threatening.
- Acute chest syndrome: This is a serious complication of sickle cell disease, characterized by respiratory symptoms, chest pain, and often a new pulmonary infiltrate on chest radiograph. Although the patient's primary complaint is leg and back pain, acute chest syndrome can present with a variety of symptoms and should not be missed.
- Rare diagnoses:
- Hemoglobinopathy other than sickle cell disease: Although the patient has a known diagnosis of sickle cell disease, it is possible that he may have a co-existing hemoglobinopathy, such as thalassemia or hemoglobin C disease. However, this would not directly explain his current symptoms.
- Other causes of bone pain (e.g., leukemia, bone tumors): These diagnoses are less likely, given the patient's history of sickle cell disease and prior similar episodes. However, they should be considered if the patient's symptoms do not respond to treatment for a sickle cell crisis.
Regarding the finding most likely to be present on the patient's peripheral smear:
- Bite cells (choice B) are the most likely finding, as they are a common feature of sickle cell disease due to the removal of Heinz bodies by the spleen. Heinz bodies are denatured hemoglobin that forms inclusions within red blood cells, which are then removed by the spleen, resulting in the formation of bite cells.