Skin & Systemic Disease Flashcards
What is acanthosis nigricans?
a skin disorder characterised by hyperpigmentation (darkening) and hyperkeratosis (thickening) of the skin
What is the texture of acanthosis nigricans like?
it often has a velvety texture
there can be papillomatoses (finger-like growths) and skin tags
Which parts of the body are usually affected by acanthosis nigricans?
- occurs in skin folds (axilla, groin, back of neck)
- can also appear on mucous membranes and the palms/soles
What causes acanthosis nigricans?
What is the main symptom?
the cause is unknown but it is thought to be related to insulin resistance
it is itchy, particularly when associated with underlying malignancy
What are the 2 different types of acanthosis nigricans?
benign & malignant
benign is much more common
What is the most common type of benign acanthosis nigricans?
obesity-related
What is syndromic benign acanthosis nigricans?
where acanthosis nigricans occurs in patients with underlying syndromes
e.g. Cushing’s disease / polycystic ovarian syndrome (PCOS)
When do lesions manifest in hereditary benign acanthosis nigricans?
this is an autosomal dominant condition in which lesions can manifest at any age
Which drugs tend to trigger drug-induced acanthosis nigricans?
- nicotinic acid
- systemic steroids
- insulin
- hormone treatments
What type of people tend to be affected by acanthosis nigricans when they are otherwise healthy?
Dark skinned individuals, particularly those of African-American background
this presents as velvety lesions over the upper surfaces of the hands and feet
What is malignant acanthosis nigricans often associated with?
90% of cases are associated with GI malignancy (especially stomach)
What is the treatment for acanthosis nigricans?
Treat the underlying cause
For the lesions themselves, treatment is only cosmetic
What is necrobiosis lipoidica and who is usually affected?
it is a rare granulomatous skin disorder
it is commonly seen in people with insulin-dependent diabetes but can occur in individuals without diabetes
it is also associated with obesity, hypertension, dyslipidaemia and thyroid disease
What does necrobiosis lipoidica look like?
- one or more tender yellow/brown patches on the lower legs
- slow developing over months to years
- commonly affects the shins and rarely found at other sites
- plaques can be asymmetrical and persist for many years
What does necrobiosis lipoidica look like as it develops?
the centre of the patch becomes shiny and pale
it is thin with prominent telangiectasia (visible blood vessels)
What can happen if there is minor trauma to the site of necrobiosis lipoidica?
this can lead to ulceration of the skin
there is then a risk of secondary bacterial infection and poor wound healing if ulceration occurs
What are the treatments for necrobiosis lipoidica?
it doesn’t always require treatment
sometimes these treatments are effective:
- topical steroids
- oral ciclosporin
- phototherapy
What is granuloma annulare and who tends to be affected?
it is a delayed hypersensitivity reaction to some component within the dermis with an unknown cause
it affects children, teenagers and young adults
Which parts of the body tend to be affected in granuloma annulare?
What are the 2 different types?
it can occur anywhere on the body
- localised disease often affects the back of the hand and is more common in younger people / children
- widespread disease is more common in adults and can be associated with diabetes & hyperlipidaemia
What do the plaques look like in granuloma annulare?
the plaques are smooth, discoloured, thickened and annular (round)
the centre of each ring is usually depressed
the affected areas are tender only when knocked and plaques tend to change appearance slowly
What is the most common treatment for granuloma annulare?
most often no treatment is required as plaques disappear in several months without a scar
sometimes they can remain for years
If treatment is needed, what are the treatment options for granuloma annulare?
- steroids / imiquimod / calcineurin inhibitors (tacrolimus)
- in widespread disease then systemic immunosuppressants or phototherapy can be used
What is erythema nodusum?
a type of panniculitis (inflammation of subcutaenous fat)
it is a hypersensitivity response, often to recent infection, in an otherwise healthy individual
What are common non-drug stimuli for erythema nodosum?
- group A streptococci
- primary tuberculosis
- pregnancy
- malignancy
- inflammatory bowel disease
- chlamydia
- leprosy
