Differential Diagnosis for 5-year-old Male Patient

The patient's symptoms of pain in alternating feet, exacerbated by sun or heat exposure, and walking, along with skin changes in the lower extremities (BLE) when exposed to sun, and nocturnal pain, suggest a range of possible diagnoses. Here is a categorized differential diagnosis:

• Single Most Likely Diagnosis

  • Sickle Cell Disease: This condition is characterized by hemoglobinopathy leading to sickling of red blood cells under certain conditions, such as heat, dehydration, or hypoxia. The sickling can cause vaso-occlusive crises, leading to pain episodes, often in the extremities, and can be triggered by exposure to heat or sun. Skin changes and nocturnal pain are also consistent with this diagnosis.

• Other Likely Diagnoses

  • Juvenile Idiopathic Arthritis (JIA): While JIA can cause joint pain and swelling, some forms can also present with systemic symptoms, including skin rashes. However, the specific pattern of pain in alternating feet and the direct association with sun exposure is less typical.
  • Erythromelalgia: A disorder characterized by burning pain, heat, and redness in the hands and feet, which can be exacerbated by heat or exercise. It's less common in children but could be considered given the symptoms.

• Do Not Miss Diagnoses

  • Neuroblastoma: A type of cancer that can cause bone pain, which may be worse at night. While less likely given the specific pattern of symptoms, it's crucial to consider due to its potential severity and the importance of early diagnosis.
  • Osteomyelitis or Septic Arthritis: Infections of the bone or joint, respectively, which can cause severe pain, especially at night, and can be associated with systemic symptoms like fever. These conditions require prompt diagnosis and treatment to prevent long-term damage.

• Rare Diagnoses

  • Fabry Disease: A genetic disorder that leads to the accumulation of a particular type of fat in the body's cells, affecting many parts of the body. It can cause pain in the hands and feet, especially after exercise or exposure to heat, but it's much less common and typically presents with other systemic symptoms.
  • Complex Regional Pain Syndrome (CRPS): A condition characterized by chronic pain, inflammation, and hypersensitivity in one of the limbs after an injury or trauma. It's rare in children and would be an unusual diagnosis given the described pattern of alternating foot pain and specific triggers.