Differential Diagnosis for a 71-year-old Female with a Maculopapular Rash
- Single most likely diagnosis:
- Drug eruption: Given the patient's age, it's likely she's on multiple medications, which increases the risk of a drug eruption. The maculopapular rash and lack of mucous membrane involvement are consistent with this diagnosis.
- Other Likely diagnoses:
- Viral exanthem: Many viral infections can cause a maculopapular rash, and the absence of mucous membrane involvement doesn't rule out this possibility.
- Contact dermatitis: Although less likely given the widespread nature of the rash, contact dermatitis could still be a consideration, especially if the patient has been exposed to a new substance.
- Seborrheic dermatitis: This condition can cause a maculopapular rash, but it typically involves the scalp, face, and intertriginous areas.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed):
- Rocky Mountain spotted fever (RMSF): Although the patient's labs are normal, RMSF can present with a maculopapular rash and non-blanching lesions on the palms. It's essential to consider this diagnosis due to its high mortality rate if left untreated.
- Meningococcemia: This condition can cause a petechial or purpuric rash, which may appear maculopapular initially. The absence of mucous membrane involvement doesn't rule out this diagnosis, and it's crucial to consider it due to its high mortality rate.
- Vasculitis: Certain types of vasculitis, such as leukocytoclastic vasculitis, can cause a maculopapular rash and non-blanching lesions. Although less likely, it's essential to consider this diagnosis due to its potential for serious complications.
- Rare diagnoses:
- Erythema multiforme: This condition typically involves mucous membranes, but it can present with a maculopapular rash in some cases.
- Sweet syndrome: Also known as acute febrile neutrophilic dermatosis, this condition can cause a maculopapular rash, but it's often accompanied by fever, neutrophilia, and other systemic symptoms.
- Parvovirus B19-associated rash: This condition can cause a maculopapular rash, but it's more commonly seen in children and young adults.