Makindo Medical Notes

Related Subjects: |Nikolsky's sign |Koebner phenomenon |Erythema Multiforme |Pyoderma gangrenosum |Erythema Nodosum |Dermatitis Herpetiformis |Lichen Planus |Acanthosis Nigricans |Acne Rosacea |Acne Vulgaris |Alopecia |Vitiligo |Urticaria |Basal Cell Carcinoma |Malignant Melanoma |Squamous Cell Carcinoma |Mycosis Fungoides (Sezary Syndrome) |Xeroderma pigmentosum |Bullous Pemphigoid |Pemphigus Vulgaris |Seborrheic Dermatitis |Pityriasis/Tinea versicolor infections |Pityriasis rosea |Scabies |Dermatomyositis |Toxic Epidermal Necrolysis |Stevens-Johnson Syndrome |Atopic Eczema/Atopic Dermatitis |Psoriasis

Look for malignancy (gastric or liver) but most commonly associated with Type 2 diabetes

About

• Characteristic rash with possible serious associations
• A cutaneous marker of insulin resistance states

Clinical

• Classically described as a velvety hyperpigmented rash and may look 'dirty'
• Found in the axillae or over the neck and flexures and the lips, palms, soles of the feet
• Most commonly seen amongst Blacks rather than whites.

Aetiology

• Insulin Resistance: Commonly associated with type 2 diabetes and obesity. Insulin resistance leads to higher levels of insulin in the blood, which may cause skin cells to reproduce more rapidly.
• Hormonal Disorders:Polycystic ovary syndrome (PCOS). Cushing's disease. Hypothyroidism.
• Medications: Certain drugs, such as oral contraceptives, corticosteroids, and niacin, can contribute to the development of acanthosis nigricans.
• Cancer:Rarely, acanthosis nigricans can be associated with cancers, particularly of the stomach and other internal organs.
• Genetics:Can occur as a genetic disorder, often presenting at birth or during childhood.

Types

• Type I (Familial): Rare. Autosomal dominant. Present at birth or develops during childhood Worsens at puberty. Not associated with cancer
• Type II (Benign): Endocrine issues. Acromegaly, gigantism, Stein-Leventhal syndrome, Cushing’s, diabetes mellitus, hypothyroidism, Addison’s disease, hyperandrogenic states, and hypogonadal syndromes
• Type III (Insulin resistance): Commonest. Obesity and insulin resistance states. Not associated with malignancy
• Type IV (Drug-induced): Nicotinic acid, niacinamide, diethylstilbestrol, triazineate, oral contraceptives, testosterone, topical fusidic acid, and glucocorticoids. Seen in 10% of renal transplant patients
• Type V (Associated with malignancy): Rare. Adults. Suspect if non obese. Some are Malignancy related. GI malignancy also lung and breast.

Typical Rash

• Dark, thickened patches of skin, usually in the neck, armpits, groin, and other body folds.
• Velvety texture to the affected areas.
• Itching or odor in some cases.

Associations

• Insulin resistance / diabetes mellitus
• Autosomal dominant inherited trait
• Gastric, oesophageal, large bowel, kidney malignancy
• Systemic lupus erythematosus
• Scleroderma, Sjogren syndrome
• Hashimoto's thyroiditis, Prader-Willi syndrome

Investigations

• Use Signs /symptoms of malignancy
• FBC/ESR/U&E/Glucose/Hba1C//TFTs
• OGD, CT CAP

Management

• Weight loss, treat causes. Treating malignancy may help
• Discontinue causative drugs
• Retinoids, keratolytics, and other topical agents to improve skin appearance.
• Metformin and other drugs to manage insulin resistance.
• Hormone therapy for endocrine disorders.
• Laser therapy or dermabrasion in severe cases.

References