Differential Diagnosis
- Single most likely diagnosis
- Furuncle (boil) or carbuncle: The patient's presentation of a tender pimple-like lesion that progressed to a vesicular rash with increased redness, swelling, and a swollen lymph node under the chin is highly suggestive of a furuncle or carbuncle, which are infections of the hair follicle and surrounding tissue, typically caused by Staphylococcus aureus.
- Other Likely diagnoses
- Folliculitis: An infection of the hair follicle, which can present similarly to a furuncle or carbuncle, but is typically less severe and may not progress to a larger, more painful lesion.
- Abscess: A collection of pus that can occur in any part of the body, including the skin, and can present with similar symptoms to a furuncle or carbuncle.
- Cellulitis: A bacterial infection of the skin and subcutaneous tissue, which can cause redness, swelling, and warmth, but typically does not start as a small, pimple-like lesion.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Necrotizing fasciitis: A rare but life-threatening infection of the skin and subcutaneous tissue, which can cause severe pain, swelling, and redness, and can progress rapidly.
- Erysipelas: A type of bacterial infection of the skin, which can cause redness, swelling, and warmth, and can be associated with a swollen lymph node, but typically has a more distinct border and may be accompanied by systemic symptoms such as fever.
- Rare diagnoses
- Hidradenitis suppurativa: A chronic skin condition characterized by recurrent, painful abscesses and nodules, typically in the apocrine-gland-bearing areas of the body, such as the axillae and groin.
- Cutaneous anthrax: A rare but potentially deadly infection caused by the bacterium Bacillus anthracis, which can cause a painless, ulcerative lesion with surrounding edema and a swollen lymph node.