Differential Diagnosis for Allergic Reaction
- Single most likely diagnosis
- Allergic contact dermatitis: The patient's symptoms of a rash on the chest and arms, along with a normal CBC and relatively normal CMP, suggest a localized allergic reaction. The elevated ALT-SGPT could be indicative of a mild hepatic response to the allergen.
- Other Likely diagnoses
- Urticaria: The presence of a rash and the patient's complaint of an allergic reaction could also suggest urticaria, especially if the rash is itchy and has a characteristic wheal-and-flare appearance.
- Atopic dermatitis (eczema): This condition could also present with a rash on the chest and arms, although it typically has a more chronic course and is associated with other symptoms like itching and dry skin.
- Drug reaction: The patient's symptoms could be due to a reaction to a medication, which would be supported by a recent change in medications or exposure to a new drug.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Anaphylaxis: Although the patient's symptoms do not currently suggest anaphylaxis (e.g., no mention of respiratory distress, cardiovascular instability, or severe swelling), this condition can rapidly progress and is life-threatening if not promptly recognized and treated.
- Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN): These severe skin reactions can be triggered by medications or infections and are associated with significant morbidity and mortality if not promptly recognized and treated.
- Rare diagnoses
- Erythema multiforme: This condition is characterized by a distinctive target-like rash and can be triggered by infections or medications. It is less common than other allergic reactions but should be considered in the differential diagnosis.
- Serum sickness: This rare condition occurs in response to certain medications or antiserum and can present with a rash, fever, and other systemic symptoms. It is an important consideration in patients with a recent history of medication exposure or antiserum administration.