Differential Diagnosis for 78-year-old Female with Burning on Top of Feet
Single Most Likely Diagnosis
- Vitamin B12 Deficiency Neuropathy: Despite taking B-12 injections, the patient's macrocytosis suggests a possible deficiency or inadequate absorption of vitamin B12. The burning sensation on the top of the feet, worse on the left, and the radiation of pain into the feet upon palpation of the foot dorsiflexors are consistent with neuropathic pain, which can be caused by vitamin B12 deficiency.
Other Likely Diagnoses
- Diabetic Neuropathy: Although not directly mentioned, long-term prednisone use can contribute to steroid-induced diabetes. The burning sensation on the feet is a common symptom of diabetic neuropathy.
- Prednisone-Induced Neuropathy: Long-term use of prednisone can lead to neuropathic symptoms, including burning sensations in the feet.
- Idiopathic Small Fiber Neuropathy: This condition can cause burning pain in the feet without a clear underlying cause, and the patient's age and symptoms are consistent with this diagnosis.
Do Not Miss Diagnoses
- Vasculitis: Although the patient has normal circulation and capillary refill time, and a normal C-reactive protein level, vasculitis can present with neuropathic symptoms and should not be missed due to its potential severity.
- Lymphoma or Leukemia: The patient's low white blood cell count and macrocytosis could be indicative of a hematologic malignancy, which would require prompt diagnosis and treatment.
- Infection (e.g., Lyme Disease): Although the patient's C-reactive protein is within normal range, infections like Lyme disease can cause neuropathic symptoms and should be considered, especially if the patient has been exposed to ticks.
Rare Diagnoses
- Amyloidosis: This condition can cause neuropathic symptoms, including burning sensations in the feet, but it is relatively rare and would require further testing for diagnosis.
- Sjögren's Syndrome: This autoimmune disorder can cause neuropathic symptoms, including burning sensations in the feet, but it is relatively rare and would require further testing for diagnosis.
- Fabry Disease: This genetic disorder can cause neuropathic symptoms, including burning sensations in the feet, but it is rare and typically presents at a younger age.