MRCP Part 1 Haematology, Infectious Disease & Dermatology 2 — Questions and Answers
Question 1: A 30-year-old man presents with erythema migrans (expanding bullseye rash) after a camping trip in the New Forest. What is the treatment of choice?
- Amoxicillin 500mg TDS for 7 days
- Doxycycline 100mg BD for 14–21 days (Correct answer)
- Ciprofloxacin 500mg BD for 7 days
- No treatment required — it is self-limiting
Correct answer: Doxycycline 100mg BD for 14–21 days
Erythema migrans is pathognomonic of early Lyme disease (Borrelia burgdorferi). Doxycycline 100mg BD for 14–21 days is the recommended treatment in the UK. Amoxicillin is an alternative. Early treatment prevents dissemination to joints, nervous system, and heart.
Question 2: A patient with HIV has a CD4 count of 80 cells/mm³ and presents with ring-enhancing lesions on MRI with surrounding oedema. What is the most likely diagnosis?
- Primary CNS lymphoma
- Cerebral toxoplasmosis (Correct answer)
- Cryptococcal meningitis
- Progressive multifocal leukoencephalopathy
Correct answer: Cerebral toxoplasmosis
Cerebral toxoplasmosis is the most common cause of ring-enhancing lesions in HIV-positive patients with a CD4 count below 200 cells/mm³. It is caused by reactivation of latent Toxoplasma gondii. Treatment is sulphadiazine plus pyrimethamine plus folinic acid.
Question 3: Which skin condition presents with salmon-pink plaques covered by silvery-white scales, affecting extensor surfaces and scalp?
- Lichen planus
- Eczema
- Psoriasis (Correct answer)
- Pityriasis rosea
Correct answer: Psoriasis
Plaque psoriasis presents with well-demarcated, erythematous plaques with silvery-white scale, affecting extensor surfaces (elbows, knees), scalp, and lumbosacral area. Auspitz sign (pinpoint bleeding when scale removed) and Koebner phenomenon are characteristic.
Question 4: A 25-year-old woman presents with an intensely pruritic papular rash in the finger webs, wrists, and waistline, worse at night. What is the most likely diagnosis and treatment?
- Eczema — treat with topical steroids
- Scabies — treat with permethrin 5% cream (Correct answer)
- Lichen planus — treat with topical tacrolimus
- Dermatitis herpetiformis — treat with dapsone
Correct answer: Scabies — treat with permethrin 5% cream
Scabies is caused by Sarcoptes scabiei mite infestation, presenting with intense nocturnal pruritus, burrows in the finger webs, wrists, and genitalia. First-line treatment is permethrin 5% cream applied from neck to toes. All household contacts must be treated simultaneously.
Question 5: In a patient with suspected meningococcal meningitis, at what point should antibiotics be given?
- Only after lumbar puncture confirms the diagnosis
- After CT head and LP are both completed
- Immediately — before investigations if there will be any delay (Correct answer)
- After blood cultures only
Correct answer: Immediately — before investigations if there will be any delay
If meningococcal meningitis or meningococcal septicaemia is suspected, IV or IM benzylpenicillin (or ceftriaxone) should be given immediately — before any investigation — as delay significantly worsens outcome. LP can be performed after treatment if meningitis is the primary concern and CT has excluded raised ICP.
Question 6: Which staging system is used for chronic lymphocytic leukaemia (CLL)?
- Ann Arbor staging
- Rai or Binet staging (Correct answer)
- Durie-Salmon staging
- International Prognostic Index
Correct answer: Rai or Binet staging
CLL is staged using either the Rai staging system (stages 0–IV, based on lymphocytosis, lymphadenopathy, organomegaly, anaemia, and thrombocytopenia) or the Binet staging system (stages A–C, used more commonly in Europe). Both correlate with prognosis and guide treatment decisions.
MRCP Part 1 Haematology, Infectious Disease & Dermatology 2
A 30-year-old man presents with erythema migrans (expanding bullseye rash) after a camping trip in the New Forest.
What is the treatment of choice?