Differential Diagnosis
The patient's presentation is complex, with multiple factors contributing to the clinical picture. The following differential diagnoses are organized into categories:
- Single Most Likely Diagnosis + Vitamin B12 deficiency: The patient's high MCV (mean corpuscular volume) and MCHC (mean corpuscular hemoglobin concentration) suggest a macrocytic anemia. The presence of gastritis and H. pylori infection, which can lead to impaired vitamin B12 absorption, supports this diagnosis. The patient's symptoms of numbness and burning in the feet at night are also consistent with vitamin B12 deficiency, which can cause peripheral neuropathy.
- Other Likely Diagnoses + Folate deficiency: Similar to vitamin B12 deficiency, folate deficiency can cause macrocytic anemia. The patient's gastritis and H. pylori infection may also contribute to impaired folate absorption. + Chronic disease anemia: The patient's long-term prednisone use and underlying autoimmune disease (myositis) may contribute to a chronic disease anemia, although the normal iron and ferritin levels make this less likely. + Anemia of chronic disease with a component of iron deficiency: Although the patient's iron and ferritin levels are normal, chronic inflammation from myositis and H. pylori infection may lead to anemia of chronic disease with a component of iron deficiency.
- Do Not Miss Diagnoses + Hematologic malignancy (e.g., myelodysplastic syndrome): Although less likely, a hematologic malignancy could present with macrocytic anemia and should be considered, especially in the context of the patient's autoimmune disease and long-term immunosuppression. + Sideroblastic anemia: This rare form of anemia can present with normal or elevated iron levels and may be associated with autoimmune diseases.
- Rare Diagnoses + Copper deficiency: Copper deficiency can cause macrocytic anemia, although it is rare and typically associated with other symptoms such as neurological abnormalities and immune system dysfunction. + Orotic aciduria: This rare genetic disorder can cause macrocytic anemia, although it is typically diagnosed in childhood and is associated with other symptoms such as developmental delay and urinary abnormalities.