Differential Diagnosis for Rash with Papules that Drain then Scar
- Single most likely diagnosis
- Acne vulgaris: This is the most common skin condition characterized by comedones (blackheads and whiteheads), papules, pustules, and sometimes cysts and nodules. The presence of papules that drain and then scar is consistent with the inflammatory component of acne, particularly when it progresses to more severe forms like nodulocystic acne.
- Other Likely diagnoses
- Folliculitis: An inflammatory condition affecting the hair follicles, often caused by bacterial or fungal infections. It can present with papules or pustules that may drain and leave scars, especially if the condition is severe or recurrent.
- Keratosis pilaris: Although typically not associated with draining papules, in some cases, especially when inflamed, it might mimic the described symptoms. However, scarring is less common.
- Pityriasis rosea: While not typically characterized by draining papules, some cases can have an inflammatory component that might lead to post-inflammatory hyperpigmentation or, rarely, scarring.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Lupus: Systemic lupus erythematosus (SLE) can cause a variety of skin manifestations, including papules that might resemble those in the question. Missing a diagnosis of lupus could have significant consequences due to its systemic nature and potential for organ damage.
- Sarcoidosis: This condition can cause skin lesions, including papules, and while less common, it's crucial not to miss due to its potential systemic involvement and the need for appropriate management.
- Infections (e.g., MRSA): Methicillin-resistant Staphylococcus aureus (MRSA) infections can cause skin lesions that might fit the description, including abscesses that drain and scar. Missing such an infection could lead to severe consequences, including sepsis.
- Rare diagnoses
- Hidradenitis suppurativa: A chronic skin condition characterized by recurrent, painful abscesses and nodules in apocrine-gland-bearing areas, which can lead to scarring. While it fits the description of draining lesions and scarring, it's less common and typically localized to specific body areas.
- Pyoderma gangrenosum: A rare condition that causes necrotic skin lesions, which can appear as papules that progress to ulcers. It's an important diagnosis not to miss due to its potential for significant morbidity, but it's much less common than other conditions listed here.