Differential Diagnosis for a 3-Week Rash on Chest and Partial Neck
Single Most Likely Diagnosis
- Tinea versicolor: A common fungal infection that can cause a rash on the chest and neck, especially after a resort vacation where the patient may have been exposed to warm and humid environments, promoting fungal growth.
Other Likely Diagnoses
- Contact dermatitis: Could be due to an allergic reaction or irritant exposure during the resort stay, such as new soaps, lotions, or plant contact.
- Pityriasis rosea: A viral rash that often starts with a herald patch, followed by a secondary eruption of smaller patches, typically on the trunk and sometimes the neck, and can be preceded by a sore throat.
- Eczema (atopic dermatitis): Could be exacerbated by environmental factors during the resort stay or by the recent sore throat, leading to a flare-up of the rash.
Do Not Miss Diagnoses
- Lyme disease: Although less likely, given the absence of a reported tick bite, it's crucial to consider due to its potential severity and the fact that early stages can present with a rash (erythema migrans) and flu-like symptoms including sore throat.
- Syphilis (secondary): Can cause a variety of rashes, including on the trunk and neck, and is accompanied by other symptoms like sore throat, making it a critical diagnosis not to miss due to its implications and treatment needs.
- Mononucleosis (infectious mononucleosis): Caused by Epstein-Barr virus, it can present with a rash, sore throat, and fever, among other symptoms, and while not typically deadly, it has significant implications for patient management and potential complications.
Rare Diagnoses
- Kawasaki disease: An acute febrile illness that can cause rash, among other symptoms, but is more common in children and would be unusual in this context without additional symptoms like fever, conjunctivitis, and lymphadenopathy.
- Zika virus or other arboviral infections: If the resort was in an area with ongoing transmission, these could be considered, especially if the patient presents with additional symptoms like fever, conjunctivitis, or arthralgias.