Differential Diagnosis for Unilateral Periorbital Oedema and Spots over Trunk
- Single Most Likely Diagnosis
- Varicella-Zoster Virus (VZV) Infection: This is likely due to the characteristic unilateral periorbital oedema and rash, which can be seen in herpes zoster (shingles) when the ophthalmic branch of the trigeminal nerve is affected. The spots over the trunk could be part of a disseminated zoster or a separate viral exanthem.
- Other Likely Diagnoses
- Herpes Simplex Virus (HSV) Infection: HSV can cause periorbital oedema and skin lesions, particularly around the eye (herpes simplex keratitis or blepharoconjunctivitis), and may also present with a rash on the trunk.
- Enterovirus Infection: Certain enteroviruses can cause hand, foot, and mouth disease or other rashes that might involve the trunk, and occasionally, periorbital oedema can be seen in the context of systemic viral infections.
- Measles: Although less common in areas with high vaccination rates, measles can cause a morbilliform rash that starts on the face and spreads to the trunk, along with periorbital oedema.
- Do Not Miss Diagnoses
- Ramsay Hunt Syndrome Type 2: Caused by VZV, this condition affects the geniculate ganglion of the facial nerve and can lead to facial paralysis, ear pain, and vesicles in the ear, along with periorbital oedema if the ophthalmic branch is involved. It's crucial to recognize this condition for timely antiviral treatment.
- Meningococcal Infection: While not typically considered a viral infection, meningococcal disease can present with a rash and, in severe cases, with signs of meningitis or sepsis. The rash can sometimes be mistaken for a viral exanthem, making it a critical "do not miss" diagnosis due to its high mortality rate if untreated.
- Rare Diagnoses
- Parvovirus B19: Known for causing the fifth disease (erythema infectiosum), it can present with a "slapped cheek" appearance and a lacy rash on the trunk. Periorbital oedema is less common but can occur.
- Dengue Fever: In endemic areas, dengue can cause a petechial rash and periorbital oedema among other symptoms like severe headache and myalgia. It's a rare consideration in non-endemic areas without travel history.