Skin Hyperpigmentation

CLINICAL DIAGNOSTIC MANUAL

Skin hyperpigmentation is a condition characterised by the darkening of specific areas of the skin due to increased melanin production. It can be caused by various factors, including sun exposure, inflammation, hormonal disorders, medications, and systemic diseases. Hyperpigmentation can affect patients’ self-esteem and, in some cases, indicate a more serious underlying medical condition.

Pathology	Suspected Diagnosis	Confirmatory Diagnosis
Freckles	Small light brown spots that increase with sun exposure.	Physical examination.
Lentigines	Dark brown spots, usually on sun-exposed areas.	Physical examination, dermatoscopy.
Drug and medication-induced	Hyperpigmentation after taking certain medications.	Clinical history, medication review.
Addison’s disease	Diffuse hyperpigmentation, fatigue, weight loss, hypotension.	Cortisol and ACTH levels, ACTH stimulation test.
Cushing’s disease	Purple striae, hyperpigmentation, central obesity, moon face.	Cortisol levels, dexamethasone suppression test.
Biliary cirrhosis	Hyperpigmentation, pruritus, jaundice.	Liver function tests, antimitochondrial antibodies (AMA).
Pemphigoid	Tense, itchy blisters, post-inflammatory hyperpigmentation.	Skin biopsy with direct immunofluorescence.
Pellagra	Photosensitive dermatitis, diarrhoea, dementia, niacin deficiency.	Clinical history, niacin levels.
Carotenemia	Yellowish skin pigmentation, especially on palms and soles, excessive carotenoid intake.	Dietary history, blood carotenoid levels.
Lichen planus	Purple papules with residual hyperpigmentation, itching.	Skin biopsy, physical examination.
Acanthosis nigricans	Brown, velvety plaques in skin folds, associated with obesity or insulin resistance.	Physical examination, insulin resistance tests.