A 36 year old male with history of psoriasis was staed on systemic steroids. After stopping treatment, the patient developed pustules in a generalized distribution. Gram stain from pustule showed only pus cells. The cause is most likely to be:
First, I need to recall what conditions can present with pustules in psoriasis patients after steroid use. Psoriasis itself can have pustular forms, like generalized pustular psoriasis (Von Zumbusch). But what triggers it? Steroids can suppress the immune system, and abrupt withdrawal might lead to a rebound effect.
Wait, when you stop steroids suddenly, especially after long-term use, the body might have adrenal suppression. But the question mentions pustules, not adrenal insufficiency symptoms. So maybe it's a psoriasis flare.
Another angle: pustules in psoriasis could be due to pustular psoriasis. The key here is the timing after stopping steroids. Systemic steroids are often used for severe psoriasis. When you stop them, especially abruptly, there's a risk of a flare-up.
Gram stain showing only pus cells suggests no bacterial infection, so it's not impetigo or another bacterial cause. So the pustules are non-infectious. Pustular psoriasis would fit here.
Other options might include something like a drug reaction, but the history of psoriasis and steroid use points more to a flare. Also, the absence of bacteria on gram stain rules out infection.
Clinical pearl: Pustular psoriasis can be triggered by withdrawal of systemic corticosteroids. The pustules are sterile, hence the gram stain shows only pus cells. High-yield fact for exams.
**Core Concept**
This question tests knowledge of **pustular psoriasis**, a severe psoriasis variant triggered by systemic steroid withdrawal. It involves keratinocyte hyperproliferation and neutrophilic infiltration, leading to sterile pustules. Key differentials include bacterial infections, but gram stains in pustular psoriasis show no organisms.
**Why the Correct Answer is Right**
The patient’s history of psoriasis and recent systemic steroid cessation strongly suggests **generalized pustular psoriasis (Von Zumbusch type)**. Steroids suppress inflammatory pathways (e.g., TNF-α, IL-17); abrupt withdrawal removes this inhibition, triggering a cytokine storm. Pustules form due to neutrophilic infiltration into the epidermis, but no bacteria are present, explaining the gram stain result.
**Why Each Wrong Option is Incorrect**
**Option A:** *Incorrect.* Bacterial infections (e.g., impetigo) would show gram-positive cocci or gram-negative rods on stain, not just pus cells.
**Option B:** *Incorrect.* Drug eruptions (e.g., Stevens-Johnson syndrome) typically present with mucocutaneous involvement and target lesions, not sterile pustules.
**Option C:** *Incorrect.* Acute generalized exanthematous pustulosis (AGEP) is drug-induced and resolves rapidly, but it lacks the psoriasis history and chronic pustular pattern.
**Clinical Pearl / High-Yield Fact**
**Steroid withdrawal can trigger pustular psoriasis.** Always taper systemic steroids gradually in psoriasis patients to prevent rebound flares. Remember: *“Steroids stop, pustules pop—psoriasis pops up