Differential Diagnosis for Monkeypox
Single Most Likely Diagnosis
- Varicella (Chickenpox): This is often considered due to the similar rash presentation, which includes vesicles and pustules in various stages of healing. However, the presence of lymphadenopathy is more characteristic of monkeypox.
Other Likely Diagnoses
- Herpes Simplex Virus (HSV) Infection: HSV can cause similar skin lesions, although they are typically more localized (e.g., genital herpes or cold sores).
- Herpes Zoster (Shingles): This condition causes a painful rash that can resemble monkeypox but usually affects a single dermatome.
- Smallpox: Although eradicated, smallpox is a consideration due to its historical significance and similar rash. However, the presence of lymphadenopathy and the milder nature of monkeypox differentiate it.
- Measles: Measles can cause a rash, but it is typically accompanied by high fever, cough, runny nose, and conjunctivitis, which are not primary features of monkeypox.
Do Not Miss Diagnoses
- Smallpox: Despite being eradicated, the potential for intentional release or misdiagnosis makes it crucial not to miss. The consequences of missing smallpox could be severe due to its high mortality rate.
- Disseminated Herpes Simplex Infection: In immunocompromised patients, HSV can disseminate and cause severe disease, including encephalitis or disseminated intravascular coagulation, making prompt diagnosis critical.
- Syphilis (Secondary): The rash of secondary syphilis can be varied and might resemble monkeypox. Missing syphilis could lead to long-term complications, including neurological and cardiovascular issues.
Rare Diagnoses
- Cowpox: A zoonotic infection that can cause similar lesions but is much rarer and typically associated with contact with infected animals.
- Vaccinia (from Smallpox Vaccination): In individuals who have received the smallpox vaccine, vaccinia can cause a localized infection that might resemble monkeypox, although this is rare.
- Orf Virus (Ecthyma Contagiosum): A zoonotic disease that causes lesions on the skin, usually acquired from contact with infected sheep or goats.
- Molluscum Contagiosum: A viral infection of the skin that causes small, pearly, or flesh-colored lesions, which could be confused with the early stages of monkeypox.