Differential Diagnosis for 75 YOF with Rash
- Single most likely diagnosis
- Shingles (Herpes Zoster): Given the description of the rash starting on one side of the chest and spreading, along with the tingling sensation, this is the most likely diagnosis. The fact that creams provided by a pharmacist were not effective also points towards a viral etiology rather than a simple dermatitis.
- Other Likely diagnoses
- Contact Dermatitis: Although the pharmacist's creams were not effective, it's possible that the initial diagnosis was incorrect or the treatment not adequate. The spread could be due to auto-eczematization.
- Eczema (Atopic Dermatitis): Could present with a widespread rash and might have a component of neuropathic sensation, though typically it's more pruritic than tingling.
- Psoriasis: Especially if the rash has distinct plaques and scales, though the tingling sensation is less typical.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Lyme Disease: If the patient has been exposed to ticks, Lyme disease could present with a rash (erythema migrans) and neurological symptoms.
- Neurosyphilis: In the context of a new rash and neurological symptoms, syphilis should be considered, especially if there's a history of unprotected sex or other risk factors.
- Vasculitis: Certain types can present with skin manifestations and neurological symptoms, though this would typically be accompanied by systemic symptoms.
- Rare diagnoses
- Pityriasis Rubra Pilaris: A rare skin disorder that can cause a widespread rash, but it's less likely to have a distinct tingling sensation.
- Sjögren's Syndrome: An autoimmune disorder that can cause skin and neurological symptoms, but it's typically associated with other systemic symptoms like dry eyes and mouth.
- Peripheral Neuropathy with Skin Manifestation: Certain neuropathies can cause skin changes and tingling, but this would be an unusual presentation without other neurological deficits.