Pathology Part 3 Flashcards
Erythroderma
Refers to the clinical state of inflammation or redness of all (or nearly all) of the skin - medical emergency
Cuases of Erythroderma
o Atopic eczema
o Psoriasis
o Drugs
o Idiopathic
Drug causes of Erythroderma
- Sulphonamides
- Gold
- Sulfonylurea
- Penicillin
- Allopurinol
Erythema nodosum
Inflammation of subcutaneous fat
Features of Erythema nodosum
> Tender, erythematous, nodular lesions
Usually occurs over shins, may also occur elsewhere
Usually resolves within 6 weeks
Lesions heal without scarring
Infection causes of Erythema nodosum
- streptococci
- tuberculosis
- brucellosis
Systemic disease causes of Erythema nodosum
- sarcoidosis
- inflammatory bowel disease
- Behcet’s
Drug causes of Erythema nodosum
penicillins
sulphonamides
combined oral contraceptive pill
Other causes of Erythema nodosum
Pregnancy and malignancy
Treatment for Erythema nodosum
- Symptomatic – NSAIDs
2. Light compression bandaging and bed rest
Erythema multiforme
A hypersensitivity reaction which is most commonly triggered by infections. It may be divided into minor and major forms.
Two types of Erythema multiforme
Erythema multiforme minor
Erythema multiforme major
Features of Erythema multiforme
> Target lesions > First back of the hands/feet before spread to torso > Pruritus > Resolves in 2-4 weeks > No mucosal involvement
Causes of Erythema multiforme
- Viruses: herpes simplex virus
- Idiopathic
- Bacteria: Mycoplasma, Streptococcus
- Drugs
- Erythematosus
- Sarcoidosis
- Malignancy
Drugs that cause Erythema multiforme
Penicillin sulphonamides carbamazepine allopurinol NSAIDs oral contraceptive pill nevirapine
Erythema multiforme major
The more severe form, erythema multiforme major is associated with mucosal involvement.
What do the target lesions in Erythema multiforme look like?
Erythematous, polycyclic, annular concentric rings
Pyoderma gangrenosum
A rare, non-infectious, inflammatory (neutrophilic dermatosis) disorder. It is an uncommon cause of very painful skin ulceration. It may affect any part of the skin, but the lower legs are the most common site.
Causes of Pyoderma gangrenosum
> idiopathic in 50% > inflammatory bowel disease in 10-15% > rheumatoid arthritis > SLE > lymphoma > Liver disease
Pyoderma gangrenosum features
Erythematous nodules or pustules that frequently ulcerate
> Bluish-black (gangrenous) edge
> May be associated pyrexia and malaise
Treatment for Pyoderma gangrenosum
- Very potent topical steroids
- Immunosuppressants used in resistant cases
- Underlying cause should be treated
Acanthosis nigricans
Describes symmetrical, brown, velvety plaques that are often found on the neck, axilla and groin.
Causes of Acanthosis nigricans
Type 2 diabetes mellitus Gastrointestinal cancer Obesity Polycystic ovarian syndrome Acromegaly Cushing's disease Hypothyroidism Familial Prader-Willi syndrome
Drugs that cause Acanthosis nigricans
- Combined oral contraceptive pill
2. Nicotinic acid
Scleroderma
Thickening or hardening of the skin owing to abnormal dermal collagen
Pathophysiology of Acanthosis nigricans
Insulin resistance → hyperinsulinemia → stimulation of keratinocytes and dermal fibroblast proliferation via interaction with insulin-like growth factor receptor-1 (IGFR1)
Management of acanthosis nigricans
Oral or topical retinoids
Dermatomyositis
A variant of polymyositis - an inflammatory disorder causing symmetrical, proximal muscle weakness and characteristic skin lesions
Features of dermatomyositis
- photosensitive
- macular rash over back and shoulder
- heliotrope rash in the periorbital region
- Gottron’s papules
- nail fold capillary dilatation
Investigations in dermatomyositis
ANA positive
anti-Jo-1
anti-SRP
anti-Mi-2 antibodies
Treatment for dermatomyositis
o Hydroxychloroquine
o Immunosuppressants
Sarcoidosis
A multisystem disorder of unknown aetiology characterised by non-caseating granulomas. It is more common in young adults and in people of African descent
Sarcoidosis features
> Erythema nodosum, > bilateral hilar lymphadenopathy, > swinging fever, > polyarthralgia > dyspnoea, > non-productive cough, > malaise, > weight loss > Hypercalcaemia
Lofgren’s syndrome
Is an acute form of sarcoidosis characterised by bilateral hilar lymphadenopathy (BHL), erythema nodosum, fever and polyarthralgia. It usually carries an excellent prognosis
Mikulicz syndrome
There is enlargement of the parotid and lacrimal glands due to sarcoidosis, tuberculosis or lymphoma
Heerfordt’s syndrome
There is parotid enlargement, fever and uveitis secondary to sarcoidosis
What are the two type of Neurofibromatosis?
NF1
NF2
Neurofibromatosis
A group of autosomal dominant genetic disorders that cause tumors to form on nerve tissue. These tumors can develop anywhere in the nervous system.
Features of NF1
- Café-au-lait spots (>= 6, 15 mm in diameter)
- Axillary/groin freckles
- Peripheral neurofibromas
- Iris hamatomas (Lisch nodules) in > 90%
- Scoliosis
- Pheochromocytomas
Café-au-lait spot
Feature of NF1 and Tuberous sclerosis
Tuberous sclerosis (TS)
A genetic condition of autosomal dominant inheritance.
Causes benign growths in many parts of the body
Features of cutaneous Tuberous sclerosis (TS)
- Depigmented ‘ash-leaf’ spots - fluoresce under UV
- Shagreen patches
- adenoma sebaceum (angiofibromas)
- Subungual fibromata
- Café-au-lait spots* may be seen
Shagreen patches
An irregularly shaped, irregularly thickened, slightly elevated soft skin-colored patch, usually on the lower back, made up of excess fibrous tissue.
Subungual fibromata
A painless, slow-growing tumor seen in the nail apparatus
Adenoma sebaceum (angiofibromas)
Refers to the reddish-brown papular rash found characteristically in a “butterfly” distribution over the face.
Bopsy and immunoflourescene is gold standard to identify and distinguish between pemphigoid and pemphigus. What are the differences seen?
Pemphigoid: linear IgG on IF
Pemphigus: scattered IgG on IF
Pemphigus vulgaris
Is an autoimmune disease caused by antibodies directed against desmoglein 3, a cadherin-type epithelial cell adhesion molecule. It is more common in the Ashkenazi Jewish population.
Features of Pemphigus vulgaris
> Mucosal ulceration
Flaccid, easily ruptured vesicles and bullae.
Nikolsky’s positive
Acantholysis on biopsy
Nikolsky’s sign
The sign is present when slight rubbing of the skin results in exfoliation of the outermost layer.