Differential Diagnosis for Old Lady with Iron Deficiency Anemia and Erythematous Rash on Tongue

Single Most Likely Diagnosis

• Pernicious Anemia: This condition is characterized by iron deficiency anemia due to a lack of intrinsic factor, leading to vitamin B12 deficiency. The erythematous rash on the tongue could be related to atrophic glossitis, a common finding in pernicious anemia. The normal gastroscopy results do not rule out pernicious anemia, as the issue lies in the autoimmune destruction of parietal cells in the stomach, not in a visible gastric lesion.

Other Likely Diagnoses

• Celiac Disease: This autoimmune disorder can lead to iron deficiency anemia due to malabsorption. Although gastroscopy might appear normal, celiac disease can cause mucosal changes that are not always visible during endoscopy. The rash on the tongue could be unrelated or part of a broader symptom complex including dermatitis herpetiformis, which is associated with celiac disease.
• Chronic Disease: Chronic diseases such as rheumatoid arthritis, chronic kidney disease, or chronic infections can lead to iron deficiency anemia. The erythematous rash on the tongue might be a separate entity or related to the underlying disease process.

Do Not Miss Diagnoses

• Gastric Cancer: Although the gastroscopy is reported as normal, it's crucial not to miss gastric cancer, especially in an older adult with iron deficiency anemia. Gastric cancer can cause iron deficiency anemia due to chronic blood loss. The normal gastroscopy results might be false negatives, or the cancer could be in a very early stage or in a location not easily visible.
• Crohn's Disease or Ulcerative Colitis: These inflammatory bowel diseases can lead to iron deficiency anemia due to chronic blood loss or malabsorption. The rash on the tongue could be part of an extraintestinal manifestation. Although gastroscopy might focus on the stomach, these diseases primarily affect the intestines, which would require separate evaluation (e.g., colonoscopy).

Rare Diagnoses

• Plummer-Vinson Syndrome: This rare disorder is characterized by iron deficiency anemia, esophageal webs, and atrophic glossitis, which could explain the erythematous rash on the tongue. It's more common in middle-aged to elderly women.
• Sjögren's Syndrome: This autoimmune disorder can cause a variety of symptoms, including oral manifestations like erythematous rash on the tongue, and can be associated with anemia due to chronic disease. It's less directly linked to iron deficiency anemia but should be considered in the differential diagnosis due to its potential for causing a wide range of symptoms.