Derm - Skin infections

Question 1

A 16yo boy presents due to pale patches developing on his back. They are mildly itchy. He has just come back from holiday in Greece.

What is the most likely diagnosis, the cause, and how would you treat?

Answer 1

Pityriasis versicolour due to proliferation of Malassezia furfur fungus.

1st line: topical ketoconazole shampoo OD 5/7
2nd line: send scrapings + confirm Dx + itraconazole PO 7/7

Question 2

A 52yo man presents due to an erythematous circular lesion with raised scaly edges on his arm.

What is the likely diagnosis, the cause, and how would you treat?

Answer 2

Tinea corporis - dermatophyte infection, usually Trichophyton spp.

Tx: topical TERBINAFINE for 1-2/52 after infection no longer visible

Question 3

A 5yo girl presents due to a circular patch of alopecia.

What is the likely diagnosis, the cause, and how would you treat?

Answer 3

Tinea capitis
dermatophyte infection, usually Trichophyton tonsurans or Microsporum canis.

Tx: KETOCONAZOLE shampoo + TERBINAFINE PO 6/52 or GRISEOFULVIN PO 4-8/52

Question 4

A 2yo is brought to the GP due to honey-coloured crusting around their mouth + nose that has spread rapidly over the last 2 days. They are systemically well.

What is the likely diagnosis, the cause, and how would you treat?

Answer 4

Impetigo: usually Staph. aureus or Strep. pyogenes.

Mx:

1. topical FUCIDIC ACID
2. wash with soap + water BD

Question 5

A 60yo lady with diabetes presents with a painful, erythematous, swollen left leg. She is systemically well.

What is the likely diagnosis, the cause, and how would you treat?

Answer 5

Cellulitis: usually group A strep or Staph spp.

Mx:

1. FLUCLOXACILLIN PO QDS 5-7/7
2. analgesia e.g. paracetamol, NSAIDs + hydration

Question 6

How would you classify the severity of cellulitis?

Answer 6

Eron classification

1. systemically well; no comorbidities
2. systemicall unwell and/or comorbidities that may complication resolution e.g. PVD, chronic venous insufficiency, obesity
3. significant systemic signs e.g. tachycardia, hypotension and/or unstable comorbidities that may interfere with response to tx or risk of limb-threatening infection due to vascular compromise
4. sepsis of severe life-threatening infection e.g. necrotising fasciitis