Pathophysiology
• Autoimmune destruction of melanocytes
• Associated with other autoimmune diseases:
o Autoimmune thyroid disease (Hashimoto’s, Graves’)
o Type 1 diabetes
o Pernicious anaemia
o Addison’s disease
Clinical features
• Depigmented macules and patches, well-defined, often symmetrical
• Common sites: periorificial areas (mouth, eyes), hands, extensor surfaces
Treatment
• Potent topical steroids
• Calcineurin inhibitors (tacrolimus) for facial lesions
• Phototherapy (narrowband UVB)
• Cosmetic camouflage
Causes
• After eczema, psoriasis, burns, trauma
• Common in darker skin types
Features
• Hyperpigmentation: excess melanin deposition in basal layer
• Hypopigmentation: temporary reduction in melanin or melanocyte function
Management
• Often resolves over time
• Sun protection to minimise contrast
Pathophysiology
• Congenital absence or defect in melanin synthesis, usually tyrosinase deficiency
• Oculocutaneous types affect skin, hair, eyes
Clinical features
• Generalised hypopigmentation of skin and hair
• Ocular signs:
o Nystagmus
o Reduced visual acuity
o Photophobia
Complications
• Markedly increased risk of UV-induced skin cancers (BCC, SCC)
Pathophysiology
• Hypermelanosis triggered by:
o Hormonal changes (pregnancy, OCP use)
o UV exposure
Clinical features
• Symmetrical hyperpigmented macules, usually on cheeks, forehead, upper lip
Management
• Sun protection
• Topical depigmenting agents (hydroquinone, azelaic acid)
• Consider retinoids
Pathophysiology
• Primary adrenal insufficiency → ↑ ACTH
• ACTH cross-reacts with melanocyte-stimulating hormone (MSH)
Clinical features
• Generalised hyperpigmentation, especially:
o Sun-exposed areas
o Pressure points (elbows, knees, knuckles)
o Buccal mucosa and palmar creases (classic exam clue)
Extra Revision Pearls
• Vitiligo + new hyperpigmentation → suspect Addison’s
• Melasma: exacerbated by sunlight and oestrogen
• Albinism: avoid excessive sun exposure; regular skin cancer surveillance
• Post-inflammatory pigment changes: especially common in Fitzpatrick skin types IV–VI
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Author & Educational Disclaimer
Author:
Dr Phillip Cockrell BM FRCP DipClinEd
Dr Phillip Cockrell is a UK Consultant Physician in Internal Medicine, currently working at Queen Alexandra Hospital, Portsmouth University Hospitals NHS Trust. He has previously worked as a registrar across Intensive Care Medicine, Gastroenterology, Cardiology, Stroke Medicine, Acute Medicine, and Respiratory Medicine.
He has held senior leadership roles including Associate Clinical Director of the Acute Medical Unit, Clinical Director of Internal Medicine, and Chief of Medicine. Dr Cockrell has over 15 years’ experience in postgraduate medical education, having lectured extensively across the MRCP syllabus and contributed to MRCP revision teaching and course development.
Dr Cockrell holds a Bachelor of Medicine (BM), Fellowship of the Royal College of Physicians (FRCP), and a Diploma in Clinical Education (DipClinEd). His teaching approach is based on structured consolidation of complex medical topics to support efficient and effective revision for postgraduate examinations.
Purpose of this content:
The material on this page is intended solely for educational purposes to support revision for the MRCP (UK) Part 1 examination. It reflects examination-relevant principles of internal medicine and is designed to aid learning and pattern recognition.
Medical disclaimer:
This content is designed for postgraduate medical examination revision and does not constitute medical advice, diagnosis, or treatment guidance and must not be used as a substitute for professional clinical judgement, local guidelines, or specialist consultation. Clinical decisions should always be made in the context of individual patient circumstances and current national guidance.
