Differential Diagnosis for the Patient's Rash

The patient presents with a new rash that started on the right hand and has spread to the left hand, both feet, and the left axilla region, following an iron infusion. The rash is characterized by discrete, elevated epirolesions with associated itching. Here is a differential diagnosis organized into categories:

• Single Most Likely Diagnosis
  • Drug Reaction to Iron Infusion: The temporal relationship between the iron infusion and the onset of the rash suggests a possible drug reaction. Iron infusions can cause allergic reactions, and the patient's symptoms are consistent with this diagnosis.
• Other Likely Diagnoses
  • Contact Dermatitis: The patient's rash is localized to specific areas (hands, feet, and axilla), which could suggest contact dermatitis. However, the lack of a clear exposure history makes this diagnosis less likely.
  • Atopic Dermatitis: The patient's itching and rash could be consistent with atopic dermatitis, especially given the presence of low iron and vitamin deficiency. However, the acute onset and distribution of the rash make this diagnosis less likely.
• Do Not Miss Diagnoses
  • Serum Sickness: This is a rare but potentially life-threatening condition that can occur after the administration of certain medications, including iron infusions. Serum sickness can cause a rash, fever, and other systemic symptoms.
  • Stevens-Johnson Syndrome: This is a severe skin and mucous membrane disorder that can be triggered by medications, including iron infusions. Stevens-Johnson syndrome can cause a rash, blisters, and other systemic symptoms.
• Rare Diagnoses
  • Erythema Multiforme: This is a rare skin condition that can cause a rash and blisters. Erythema multiforme can be triggered by medications, infections, and other factors.
  • Pityriasis Rosea: This is a rare skin condition that can cause a rash and itching. Pityriasis rosea can be triggered by viral infections and other factors.

It is essential to note that the patient's symptoms and history should be thoroughly evaluated, and further investigations (e.g., laboratory tests, skin biopsies) may be necessary to confirm the diagnosis.