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DR1.1-2 | Acne — PBL Case

CLINICAL SETTING

Rahul, a 20-year-old male engineering student, is referred to the dermatology OPD by the campus health centre. He reports a 3-year history of acne that has worsened over the past year despite multiple treatments. He is visibly distressed about his appearance and mentions that the acne has affected his social interactions. **On examination:** - Multiple open and closed comedones on the forehead and nose - Papules and pustules on both cheeks, chin, and jawline - Three large, tender nodules on the right cheek measuring 1–2 cm - Superficial ice-pick scars on both cheeks - No lesions on trunk or back - No fever; general examination is unremarkable **History of treatments:** - 18 months ago: topical clindamycin 1% gel alone, used for 9 months, minimal improvement - 3 months ago: added oral doxycycline 100 mg OD; some initial improvement but acne has worsened again in the last 6 weeks - Currently: still on doxycycline 100 mg OD + topical clindamycin gel His mother, who accompanied him, asks: 'Doctor, we have heard that there is a tablet that can cure acne completely. Why hasn't he been given it yet?'

Trigger 1: Trigger 1 — Diagnosis, Grading, and Treatment Failure

The facilitator asks the group to pause after reading the case stem. Additional information to share with students: - Rahul's acne started at age 17 with primarily comedonal lesions that progressed over time - Family history: his father had severe acne in his twenties - He has been applying the topical clindamycin twice daily as instructed - He denies picking or squeezing lesions - No corticosteroid use, no dietary changes

DISCUSSION POINTS

Assign an IGA grade AND estimate a GAGS score range for Rahul's acne. What specific features in the examination justify your grading?
Rahul has been on oral doxycycline + topical clindamycin for 3 months and is now worsening again. Propose the most likely pharmacological explanation for this secondary failure. What should have been added to his regimen from the beginning to prevent this?
Why is the presence of nodules clinically significant? How do nodules differ pathologically from papules and pustules, and why do they carry a higher risk of permanent scarring?

Click to reveal Trigger 2: Trigger 2 — Isotretinoin Decision (discuss previous trigger first!)

Trigger 2: Trigger 2 — Isotretinoin Decision

After the group discusses grading and treatment failure, the facilitator shares the following: Rahul's mother repeats her question about the 'tablet that cures acne'. The supervising consultant says: 'Rahul's presentation does satisfy the indications for oral isotretinoin.' Baseline investigations ordered: - Fasting lipids: Triglycerides 1.8 mmol/L (normal: <1.7 mmol/L — mildly elevated), LDL normal, HDL normal - LFTs: all normal - CBC: normal Rahul asks: 'Will this tablet have any side effects? My friend told me it can affect the brain and also cause depression. Is that true?'

DISCUSSION POINTS

List the indications for oral isotretinoin that Rahul's case satisfies. What is the standard dosing approach (dose range per kg, target cumulative dose) and why does cumulative dose matter?
How would you counsel Rahul (not his mother) about the adverse effect profile of isotretinoin? Address: (a) the mildly elevated triglycerides — is this a contraindication?, (b) the question about psychiatric effects, and (c) one truly absolute contraindication that, while not applicable to Rahul, the group must know.
The doxycycline + topical clindamycin combination must be stopped before isotretinoin is started. Propose a transition plan and explain the rationale for stopping each component.

Click to reveal Trigger 3: Trigger 3 — Week 6 Paradoxical Flare (discuss previous trigger first!)

Trigger 3: Trigger 3 — Week 6 Paradoxical Flare

Rahul returns to clinic 6 weeks after starting isotretinoin 0.5 mg/kg/day (35 mg/day). His mother calls the clinic urgently: Rahul has developed new ulcerating lesions on his chest and back. He now has fever (38.6°C), joint pains in both knees, and has lost 2 kg. On review: - Chest and back: multiple haemorrhagic, crusted nodules and coalescent plaques with some ulceration - Both knees: tender, no swelling, no restriction of movement - Face: paradoxically, the facial acne appears to have improved - CRP: 48 mg/L (elevated); CBC: mild leucocytosis

DISCUSSION POINTS

What is the most likely diagnosis for this new presentation? How does it differ from acne fulminans that occurs WITHOUT isotretinoin, and from acne conglobata?
What immediate management changes would you make to Rahul's isotretinoin therapy, and what adjunctive systemic treatment should be added? Explain the mechanism by which this adjunct controls the systemic features.
In retrospect, identify the clinical risk factor in Rahul's original presentation that should have prompted a lower starting dose of isotretinoin (0.25 mg/kg rather than 0.5 mg/kg). How does starting low reduce the risk of this complication?

Click to reveal Trigger 4: Trigger 4 — Long-term Outcome and Scar Management Discussion (discuss previous trigger first!)

Trigger 4: Trigger 4 — Long-term Outcome and Scar Management Discussion

Rahul stabilises on systemic corticosteroids and a reduced dose of isotretinoin (0.25 mg/kg/day). At 6 months, his acne is completely clear. He completes his cumulative dose target. At the 6-month review, Rahul points to his cheeks and asks about the ice-pick scars that were present before treatment. The consultant also notes that a new female patient in the next room has been referred by her GP for 'acne-like rash' — she has papulopustular lesions on the forehead and cheeks, no comedones, and flushing with red wine.

DISCUSSION POINTS

Rahul asks whether isotretinoin can reverse existing scars. What is the correct answer, and what scar-management options exist for ice-pick scars? (Students are not expected to know procedural details — focus on the principle of treatment and why isotretinoin alone is insufficient.)
How would you approach the new patient in the next room? Identify the key clinical feature that distinguishes her presentation from Rahul's acne vulgaris, and propose the most likely diagnosis with your reasoning.
Looking back across Rahul's full journey, construct a 'lessons from this case' summary: identify three decision points where an earlier or different intervention could have altered his outcome (antibiotic resistance, starting dose of isotretinoin, flare management). This is your integrative synthesis of DR1.1 and DR1.2.