Differential Diagnosis for the Patient's Rash
The patient presents with a red, raised, and itchy rash bilaterally on her arms, which appeared and partially resolved within a day. Considering the symptoms and the transient nature of the rash, the following differential diagnoses are proposed:
- Single Most Likely Diagnosis
- Contact Dermatitis: This is the most likely diagnosis given the sudden onset and resolution of the rash, along with its itchy and raised nature. The patient's exposure to a new substance at work could have triggered an allergic reaction, leading to contact dermatitis.
- Other Likely Diagnoses
- Urticaria (Hives): The rash's appearance and disappearance could also suggest urticaria, especially if the patient has a history of allergies or recent exposure to allergens.
- Atopic Dermatitis (Eczema): Although less likely given the acute onset, atopic dermatitis could be considered if the patient has a history of eczema or other atopic conditions.
- Irritant Contact Dermatitis: Similar to allergic contact dermatitis but caused by a non-allergic, irritant substance, which could have been encountered at work.
- Do Not Miss Diagnoses
- Stevens-Johnson Syndrome (SJS) or Toxic Epidermal Necrolysis (TEN): Although rare and less likely given the description, these conditions are life-threatening and require immediate attention. They are usually associated with medication use and can present with skin lesions, but the patient's rash does not seem to fit the typical severe presentation of SJS/TEN.
- Infectious Causes (e.g., Impetigo, Cellulitis): Bacterial infections could cause a rash, but the bilateral and symmetric nature of the patient's rash, along with its itchy character, makes this less likely. However, it's crucial not to miss infectious causes that could require antibiotic treatment.
- Rare Diagnoses
- Pityriasis Rosea: Characterized by a herald patch followed by a secondary eruption of oval-shaped lesions, which doesn't exactly match the patient's description but could be considered in the differential for rash diagnoses.
- Dermatologic Manifestations of Systemic Diseases: Certain systemic diseases (e.g., lupus, rheumatoid arthritis) can have dermatologic manifestations, but these would typically be accompanied by other systemic symptoms, which the patient does not report.