Differential Diagnosis for 65 yo f with Red Edematous Reticular Rash
- Single most likely diagnosis
- Allergic reaction to contrast media: This is the most likely diagnosis given the temporal relationship between the nuclear medicine study and the onset of the rash. The rash appeared 2 hours after the study, which is a common time frame for an allergic reaction to contrast media.
- Other Likely diagnoses
- Contact dermatitis: Although less likely, contact dermatitis could be considered if the patient came into contact with an allergen or irritant during the nuclear medicine study.
- Urticaria: Urticaria is a possible diagnosis given the itchy and painful nature of the rash, but it is less likely than an allergic reaction to contrast media.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Anaphylaxis: Although the patient does not have airway problems, anaphylaxis is a life-threatening condition that can progress rapidly. It is essential to consider this diagnosis, even if it seems unlikely.
- Stevens-Johnson syndrome: This is a rare but life-threatening condition that can be triggered by an allergic reaction. It is crucial to monitor the patient for signs of Stevens-Johnson syndrome, such as mucosal involvement and skin necrosis.
- Rare diagnoses
- Erythema multiforme: This is a rare skin condition that can be triggered by an allergic reaction or infection. It is characterized by a distinctive target-like rash.
- Serum sickness-like reaction: This is a rare condition that can occur after exposure to certain medications or contrast media. It is characterized by a rash, fever, and arthralgias.