Onychomycosis - causes, risk factors, features , DD, investigation, management
Onychomycosis is fungal infection of the nails. This may be caused by
- dermatophytes - mainly Trichophyton rubrum, accounts for 90% of cases
- yeasts - such as Candida
- non-dermatophyte moulds
Risk factors include for fungal nail infections include diabetes mellitus andincreasing age.
Features
- ‘unsightly’ nails are a common reason for presentation
- thickened, rough, opaque nails are the most common finding
Differential diagnosis
- psoriasis
- repeated trauma
- lichen planus
- yellow nail syndrome
Investigation
- nail clippings
- scrapings of the affected nail
- the false-negative rate for cultures are around 30%, so repeat samples may need to be sent if the clinical suspicion is high
Management
- do not need to be treated if it is asymptomatic and the patient is not bothered by the appearance
- diagnosis should be confirmed by microbiology before starting treatment
- dermatophyte infection:
- -oral terbinafine is currently recommended first-line with oral itraconazole as an alternative
- -6 weeks - 3 months therapy is needed for fingernail infections whilst toenails should be treated for 3 - 6 months
- -treatment is successful in around 50-80% of people
- Candida infection:
- -mild disease should be treated with topical antifungals (e.g. Amorolfine) whilst more severe infections should be treated with oral itraconazole for a period of 12 weeks
- if topical topical treatment is given treatment should be continued for 6 months for fingernails and 9-12 months for toenails
Lichen planus - Features, causes, management
Lichen planus is a skin disorder of unknown aetiology, most probably being immune-mediated.
Features
- itchy, papular rash most common on the palms, soles, genitalia and flexor surfaces of arms
- rash often polygonal in shape, with a ‘white-lines’ pattern on the surface (Wickham’s striae)
- typically a symmetrical white lace-like pattern on the buccal mucosa
- Koebner phenomenon may be seen (new skin lesions appearing at the site of trauma)
- oral involvement in around 50% of patients: typically a white-lace pattern on the buccal mucosa
- nails: thinning of nail plate, longitudinal ridging
Lichenoid drug eruptions - causes:
- gold
- quinine
- thiazides
Management
- topical steroids are the mainstay of treatment
- benzydamine mouthwash or spray is recommended for oral lichen planus
- extensive lichen planus may require oral steroids or immunosuppression
Nail signs ?
Nail pitting
- psoriasis
- alopecia areata
Blue nails
- Wilson’s disease
Leuconychia
- hypoalbuminaemia
- less common: fungal disease, lymphoma
Half and half
- distal portion brown and proximal portion pale
- chronic renal failure
Nail patella syndrome
Yellow nail syndrome
- associated with congenital lymphoedema, pleural effusions, bronchiectasis and chronic sinus infections
Contact dermatitis
There are two main types of contact dermatitis
irritant contact dermatitis:
- common - non-allergic reaction due to weak acids or alkalis (e.g. detergents). Often seen on the hands. Erythema is typical, crusting and vesicles are rare
- allergic contact dermatitis: type IV hypersensitivity reaction. Uncommon - often seen on the head following hair dyes. Presents as an acute weeping eczema which predominately affects the margins of the hairline rather than the hairy scalp itself. Topical treatment with a potent steroid is indicated
Cement is a frequent cause of contact dermatitis. The alkaline nature of cement may cause an irritant contact dermatitis whilst the dichromates in cement also can cause an allergic contact dermatitis
Patch testing is the investigation of choice for suspected allergic contact dermatitis. Various allergens are applied to the patient’s back, and the skin assessed at 48 hours and 7 days for any reaction. Standard batteries of allergens are used, in addition to samples of any substances the patient suspects.
What is purpura?
Purpura describes bleeding into the skin from small blood vessels that produces a non-blanching rash. Smaller petechiae (1-2 mm in diameter) may also be seen. It is typically caused by low platelets but may also be seen with bleeding disorders, such as von Willebrand disease.
It is important to recognise purpura as it can indicate the presence of serious underlying disease. Children with a new purpuric rash should be admitted immediately for investigations as it may be a sign of meningococcal septicaemia or acute lymphoblastic leukaemia. Parenteral antibiotics should be given prior to transfer if meningococcal septicaemia is suspected.
Causes of purpura? in children
Meningococcal septicaemia • Acute lymphoblastic leukaemia • Congenital bleeding disorders • Immune thrombocytopenic purpura • Henoch-Schonlein purpura • Non-accidental injury
Causes of purpura? in adults
- Immune thrombocytopenic purpura
- Bone marrow failure (secondary to leukaemias, myelodysplasia or bone metastases)
- Senile purpura
- Drugs (quinine, antiepileptics, antithrombotics)
- Nutritional deficiencies (vitamins B12, C and folate)
Raised superior vena cava pressure (e.g. secondary to a bad cough) may cause… ?
Petechiae in the upper body but would not cause purpura.
When is purpura a normal finding in children?
Purpura are never a normal finding in children
- needs to be immediately admitted to exclude ALL and meningococcal disease
Leukoplakia
Leukoplakia is a premalignant condition which presents as white, hard spots on the mucous membranes of the mouth. It is more common in smokers.
Leukoplakia is said to be a diagnosis of exclusion. Candidiasis and lichen planus should be considered, especially if the lesions can be ‘rubbed off’
Biopsies are usually performed to exclude alternative diagnoses such as squamous cell carcinoma and regular follow-up is required to exclude malignant transformation to squamous cell carcinoma, which occurs in around 1% of patients.
The difference between features of leukoplakia and candidiasis?
The asymptomatic and prolonged nature of the symptoms goes against a diagnosis of candidiasis
Hyperhidrosis - management
Management options include
- topical aluminium chloride preparations are first-line. Main side effect is skin irritation
- iontophoresis: particularly useful for patients with palmar, plantar and axillary hyperhidrosis
- botulinum toxin: currently licensed for axillary symptoms
- surgery: e.g. Endoscopic transthoracic sympathectomy. Patients should be made aware of the risk of compensatory sweating
1st line - aluminium chloride
2nd line - Botulinum toxin injections and topical glycopyrrolate (an antimuscarinic agent)
Causes of pruritus ? Features?
- Liver disease - History of alcohol excess
Stigmata of chronic liver disease: spider naevi, bruising, palmar erythema, gynaecomastia etc
Evidence of decompensation: ascites, jaundice, encephalopathy - Iron deficiency anaemia - Pallor
Other signs: koilonychia, atrophic glossitis, post-cricoid webs, angular stomatitis - Polycythaemia - Pruritus particularly after warm bath
‘Ruddy complexion’
Gout
Peptic ulcer disease
Blood results - increased Hb, platelets, WBC - Chronic kidney disease -Lethargy & pallor (anaemia as. a result of a lack of EPO - more likely to be a normochromic normocytic anaemia )
Oedema & weight gain
Hypertension
- Lymphoma - Night sweats Lymphadenopathy Splenomegaly, hepatomegaly Fatigue Deranged WBC Low platelets
Other causes: hyper- and hypothyroidism diabetes pregnancy 'senile' pruritus urticaria skin disorders: eczema, scabies, psoriasis, pityriasis rosea
Skin disorders associated with SLE
Skin manifestations of systemic lupus erythematosus (SLE) - photosensitive 'butterfly' rash (the malar rash has nasolabial sparing) - discoid lupus - alopecia - livedo reticularis: net-like rash
Bullous pemphigoid- feature , investigation finding, mx
Bullous pemphigoid is an autoimmune condition causing sub-epidermal blistering of the skin. This is secondary to the development of antibodies against hemidesmosomal proteins BP180 and BP230
Bullous pemphigoid is more common in elderly patients. Features include
- itchy, tense blisters typically around flexures
- the blisters usually heal without scarring
- mouth is usually spared*
(*in reality around 10-50% of patients have a degree of mucosal involvement. It would however be unusual for an exam question to mention mucosal involvement as it is seen as a classic differentiating feature between pemphigoid and pemphigus.)
Skin biopsy
- immunofluorescence shows IgG and C3 at the dermoepidermal junction
Management
- referral to dermatologist for biopsy and confirmation of diagnosis
- oral corticosteroids are the mainstay of treatment
- topical corticosteroids, immunosuppressants and antibiotics are also used
Squamous cell carcinoma of the skin - risk factors, treatment, good/poor prognosis factors
Squamous cell carcinoma is a common variant of skin cancer. Metastases are rare but may occur in 2-5% of patients.
Risk factors include:
- excessive exposure to sunlight / psoralen UVA therapy
- actinic keratoses and Bowen’s disease
- immunosuppression e.g. following renal transplant, HIV
- smoking
- long-standing leg ulcers (Marjolin’s ulcer)
- genetic conditions e.g. xeroderma pigmentosum, oculocutaneous albinism
Treatment:
Surgical excision with 4mm margins if lesion <20mm in diameter. If tumour >20mm then margins should be 6mm. Mohs micrographic surgery may be used in high-risk patients and in cosmetically important sites.
Good prognosis:
- Well differentiated tumours
- <20mm diameter
- <2mm deep
- No associated diseases
Poor prognosis:
- Poorly differentiated tumours
- > 20mm in diameter
- > 4mm deep
- Immunosupression for whatever reason
Spider naevi
Spider naevi (also called spider angiomas) describe a central red papule with surrounding capillaries. The lesions blanch upon pressure. Spider naevi are almost always found on the upper part of the body.
Spider naevi can be differentiated from telangiectasia by pressing on them and watching them fill. Spider naevi fill from the centre, telangiectasia from the edge .
Around 10-15% of people will have one or more spider naevi and they are more common in childhood. Other associations
- liver disease
- pregnancy
- combined oral contraceptive pill
Acne rosacea - features, management
Acne rosacea is a chronic skin disease of unknown aetiology.
Features
- typically affects nose, cheeks and forehead
- flushing is often first symptom
- telangiectasia are common
- later develops into persistent erythema with papules and pustules
- rhinophyma
- ocular involvement: blepharitis
- sunlight may exacerbate symptoms/
Management
- topical metronidazole may be used for mild symptoms (i.e. Limited number of papules and pustules, no plaques)
- topical brimonidine gel may be considered for patients with predominant flushing but limited telangiectasia
- more severe disease is treated with systemic antibiotics e.g. Oxytetracycline
- recommend daily application of a high-factor sunscreen
- camouflage creams may help conceal redness
- laser therapy may be appropriate for patients with prominent telangiectasia
- patients with a rhinophyma should be referred to dermatology
Lichen sclerosus -features , management, follow up
It is an inflammatory condition which usually affects the vulva and is more common in elderly females. Lichen sclerosus leads to atrophy of the epidermis with white plaques forming
Features
- itch is prominent
The diagnosis is usually made on clinical grounds but a biopsy may be performed if atypical features are present -Biopsy is required if the woman fails to respond to treatment or there is clinical suspicion of VIN or cancer
Management
- topical steroids and emollients
1st line - strong topical steroid - topical clobetasol propionate
2nd line - the disease will be resistant to steroids and in this case topical tacrolimus is the next line of treatment however this is only initiated in specialist clinics
Follow-up:
- increased risk of vulval cancer
Blisters/bullae, no mucosal involvement therefore is…
( no mucosal involvement in exams at least)
bullous pemphigoid
Blisters/bullae, mucosal involvement therefore is…
pemphigus vulgaris
Pityriasis rosea - features and management
Pityriasis rosea describes an acute, self-limiting rash which tends to affect young adults. The aetiology is not fully understood but is thought that herpes hominis virus 7 (HHV-7) may play a role.
Features
- in the majority of patients there is no prodrome, but a minority may give a history of a recent viral infection
- herald patch (usually on trunk)
- followed by erythematous, oval, scaly patches which follow a characteristic distribution with the longitudinal diameters of the oval lesions running parallel to the line of Langer. This may produce a ‘fir-tree’ appearance
Management
- self-limitingm - usually disappears after 6-12 weeks
Differentiating guttate psoriasis and pityriasis rosea
- PRODROME =
Guttate- Classically preceded by a streptococcal sore throat 2-4 weeks
Pityriasis rosea - Many patients report recent respiratory tract infections but this is not common in questions - APPEARANCE =
Guttate - ‘Tear drop’, scaly papules on the trunk and limbs
Pityriasis -Herald patch followed 1-2 weeks later by multiple erythematous, slightly raised oval lesions with a fine scale confined to the outer aspects of the lesions.
May follow a characteristic distribution with the longitudinal diameters of the oval lesions running parallel to the line of Langer. This may produce a ‘fir-tree’ appearance - TREATMENT/NATURAL HISTORY
Guttate - Most cases resolve spontaneously within 2-3 months
Topical agents as per psoriasis
UVB phototherapy
Pityriasis- Self-limiting, resolves after around 6 weeks
Erythema nodosum
Overview
- inflammation of subcutaneous fat
- typically causes tender, erythematous, nodular lesions
- usually occurs over shins, may also occur elsewhere (e.g. forearms, thighs)
- usually resolves within 6 weeks
- lesions heal without scarring
Causes
- infection
- streptococci
- tuberculosis
- brucellosis - systemic disease
- sarcoidosis
- inflammatory bowel disease
- Behcet’s - malignancy/lymphoma drugs
- penicillins
- sulphonamides
- combined oral contraceptive pill - pregnancy
