Skin disease is marked by its variety and visibility. Dermatology is a field where pattern recognition and analysis are critical so experience is key - having seen something previously makes it much easier to recognise it in the future. Accurate history taking and examination are as important as in any other field of medicine. A systematic approach is required, although this may become truncated with experience; however, even the most experienced doctor will have the occasional difficult case where it is necessary to go back to basics.
The diagnosis and management of skin disease makes up a large component of Primary Care and most GPs develop diagnostic and surgical skills to deal with this demand. In recent years, nurses have been more involved in the provision of dermatological care as well as having to make diagnoses in circumstances such as a walk-in clinic.
- Add notes to any clinical page and create a reflective diary
- Automatically track and log every page you have viewed
- Print and export a summary to use in your appraisal
As always, this is the starting point:
- Note basic demographics of the patient:
- Age - infectious diseases are more common in children but malignancy gets more common with advancing age.
- Sex - some conditions are more common in men or more common in women.
- Race and country of origin.
- Current residence - important in an infectious outbreak.
- Consider the lesion:
- Onset - sudden versus gradual? Is this an acute presentation or an ongoing chronic problem?
- Previous episodes, eg photodermatoses tend to reoccur every spring with the onset of good weather.
- Change - fluctuation versus persistence? Consider variation in severity, eg occupational contact allergic dermatitis may improve when on holiday. Urticaria may be quite dynamic in its presentation but others are much more static.
- Location: as well as skin, remember mucous membranes. The site of lesions is important. Eczema tends to be on flexural surfaces (in adults and older children) whilst psoriasis tends to be on extensor parts. Lesions may have a specific distribution - around the genitals, in sweaty regions or sun-exposed areas. Has the lesion spread?
- Provoking or relieving factors, eg heat and cold may be either aggravating or relieving factors, especially with urticaria, repeated drug exposures with fixed drug eruptions.
- Associated symptoms:
- Itch - some lesions are renowned for being itchy and others for not being so but this can be misleading. Psoriasis is said to be non-itchy but there may be pruritus in the genital area.
- Tenderness - inflammation is often tender.
- Bleeding or discharge - bleeding may indicate malignancy and discharge may occur with an infected lesion.
- Systemic symptoms such as pyrexia, malaise, joint pain and swelling or weight loss. Some skin lesions are markers for underlying malignancy.
- Response to treatment - both patient and doctor initiated. A number of treatments may have been tried prior to consultation eg antiseptic lotions, calamine, antihistamines, over-the-counter (OTC) steroid or antifungal creams, herbal remedies or medication prescribed for another family member or friend. Complementary medicines such as chinese herbs may have unknown ingredients and potency. Partially treated lesions are the most difficult to diagnose.
Do not forget to cover:
- Past medical history, which is often relevant, eg diabetes may suggest necrobiosis lipoidica.
- Family history, which may indicate a familial trend for the disease. Other family members will have been given a diagnosis. A genetic predisposition is important in many diseases including eczema and psoriasis. Alternatively, concurrent and recent affliction of other members of the family suggest a contagious or environmental aetiology. Familial atypical mole and melanoma (FAMM) syndrome should be considered where several family members have multiple melanocytic lesions, some atypical, with at least one case of melanoma in the family.
- Occupation, hobbies and pastimes, where there may be exposure to chemicals or a very hot environment, for example.
- Travel, particularly to exotic locations, may increase the risk of rarer tropical diseases. Consider cumulative exposure to sunlight or sunbeds and history of sunburn as these increase the risk of skin malignancies.
- Drugs, prescribed, over-the-counter or other therapies. Drug eruptions can be highly variable. Illegal drug use may have dermatological manifestations, eg anabolic steroids and acne.
- Smoking and alcohol- alcohol use has an association with psoriasis and smoking increases the risk of some malignancies and has a close association with palmoplantar pustular psoriasis.
- Psychological and social sequelae - people with severe, chronic, visible and disfiguring skin disease may suffer from anxiety, depression and social isolation, these issues require exploration. Psychological problems may also cause skin disease, eg dermatitis artefacta. See separate article Living with Skin Disease.
In general, a thorough examination of the whole skin is considered best practice but may not be warranted, eg diagnosis of a verruca.
First just look:
- Does the patient look ill or well? Are there any clues as to systemic illness?
- Wipe off any creams, makeup or anything else that may obscure the true nature of the lesions.
Now focus on the lesion(s):
- Note the position of lesions:
- Is the distribution symmetrical or asymmetrical? (Symmetrical distribution suggests an endogenous condition such as psoriasis, whilst asymmetry is more typical of an exogenous condition such as tinea.) Some rashes have a characteristic distribution such as with shingles.
- Flexor or extensor surfaces?
- Areas of friction or pressure?
- Sweaty regions?
- Exposed regions?
- Related to sexual contact? (consider genital lesions but also the lower abdomen and upper thighs).
- Note the size of the lesion. Measure for accuracy.
- Is it single or multiple?
- If a rash exists, what is its morphology? Are individual lesions:
- Note colour, shape, regularity or irregularity. Are there areas of inflammation around it? Is the edge clearly demarcated or poorly defined?
The use of dermatoscopy may aid diagnosis beyond naked eye examination but should only be used by those with appropriate training.
- Site within the skin.
- Consistency (hard, soft, firm, fluctuant).
- Does firm pressure lead to blanching?
- Is it friable? Does it bleed easily?
- Scaling - disorders of the epidermis may produce scale, which may be visible, or gentle scratching of the skin may make it apparent.
- If appropriate, look to see if there is any evidence of infestation, e.g scabies' burrows.
- Note hair in the local skin and on the head.
- Look at the nails.
- Are mucous membranes involved? Examine the genitals where appropriate.
- Are there regional lymph nodes? This may be relevant for infectious or malignant lesions.
Having completed the full history and examination, it is usually possible to make a firm diagnosis but, if not, it is certainly possible to distil a great deal of information about the condition. Very often the impressive names that dermatologists give to unusual conditions are nothing more than a description in Latin. Beware of the 'great mimickers', eg amelanotic melanoma, lupus erythematosus, sarcoid, mycobacteria and cutaneous T-cell lymphoma. Diagnostic tables and algorithms have been developed to complement clinical acumen.
Where a firm diagnosis cannot be made with a reasonable degree of confidence, investigations may be helpful and even a therapeutic trial may be beneficial. However, steroid cream can mask some aspects of a disease and dermatologists often complain of the difficulties of diagnosing partially treated disease. Teledermatology is fundamentally changing primary care's access to an expert opinion on a skin condition although concerns persist about reduced diagnostic reliability and the ongoing need for face-to-face consultations, particularly in the diagnosis of skin malignancies.
One of the most important decisions to make about a skin lesion is whether or not it is malignant. There must be a high index of suspicion and absolute certainty is rare. For pigmented lesions, change is an important element in diagnosing malignant melanoma. Current guidelines suggest assessing on a weighted 7-point scale:
- Change in size
- Irregular shape
- Irregular colour
- Largest diameter 7 mm or more
- Change in sensation
Suspicion is greater for lesions scoring 3 points or more but, if there are strong concerns, any one feature is sufficient to prompt urgent referral, as should:
- Any new solitary nodule or plaque regardless of colour where a benign diagnosis (eg a dermatofibroma) cannot be made with confidence. Half of nodular melanomas are hypomelanotic or amelanotic and may present as a pink nodule.
- A new pigmented line in a nail.
- Lesions growing under a nail.
- Pigmented lesions on mucosal surfaces.
These can be taken for bacteriology and virology.
- Skin scrapings for microscopy can be useful to diagnose fungal infections, pityriasis versicolor and ectoparasitic infections such as scabies. For dermatophyte infections, scrape the advancing edge of the scaly lesion carefully.
- Nail clippings - ensure a good-sized clipping and scrape from the under the surface of the nail.
- Hair root samples can be useful in suspected tinea capitis.
Most laboratories will supply appropriate specimen containers - usually small envelopes with a black interior as it is much easier to see the sample against such a background.
This is an ultraviolet light (wavelength 360-365 nm) used in a darkened room. It should be held at least 10-15 cm from the skin and time should be allowed for dark accommodation to occur. When shone on some fungal infections, the light causes fluorescence.
- Tinea versicolor fluoresces with subtle gold colours.
- Erythrasma due to Corynebacterium minutissimum fluoresces a bright coral red.
- Tinea capitis caused by Microsporum canis and Microsporum audouinii fluoresce a light bright green but most tinea capitis infections are caused by Trichophyton species that do not fluoresce.
Pseudomonas aeruginosa infection, especially in burns, may provide green-yellow fluorescence.
Vitiligo also fluoresces. Its associated depigmentation can be differentiated from hypopigmented lesions by the ivory-white colour under Wood's light.
Wood's light can also be used in the evaluation of pigmented lesions, marking out areas of lentigo maligna or melasma.
- Biopsy may be used to provide a histopathological specimen to aid diagnosis and guide further management. Always provide relevant history, description and differential diagnosis to assist the histopathologist. Histology may not be able to differentiate between some cases of dysplastic naevi and melanoma so that any case of incompletely excised 'dysplastic naevus' should be referred for a further excision.
- Shave and punch biopsy techniques can be used. Shave excisions are less demanding technically, and are useful when the lesion is small and the risk of malignancy is low. Punch biopsies remove a core of skin from the epidermis to subcutaneous fat. Ideally the biopsy should include normal skin, part of the lesion and the transition zone. Excisional biopsies aim to remove the entire lesion, with a margin dependent on the risk of malignancy. Its advantage is that the procedure can provide treatment as well as diagnosis for many lesions but it is more demanding of time, equipment and expertise.
- Biopsy can also be used for immunofluorescence and culture (eg mycobacterium, leishmaniasis).
Patch and skin prick tests
These are used for the investigation of contact allergic dermatitis and suspected latex and other allergies.
Further reading & references
- Terminology in dermatology, DermNet NZ
- University of Wisconsin Nomenclature of skin lesions; Tutorials and photos aimed at improving description of skin lesions
- Primary Care Society for Dermatology
- Courtenay M, Carey N; Nurse-led care in dermatology: a review of the literature. Br J Dermatol. 2006 Jan;154(1):1-6.
- Ersser SJ, Lattimer V, Surridge H, et al; An analysis of the skin care patient mix attending a primary care-based nurse-led NHS Walk-in Centre. Br J Dermatol. 2005 Nov;153(5):992-6.
- Kleyn CE, Lai-Cheong JE, Bell HK; Cutaneous manifestations of internal malignancy: diagnosis and management. Am J Clin Dermatol. 2006;7(2):71-84.
- Ramsay HM, Goddard W, Gill S, et al; Herbal creams used for atopic eczema in Birmingham, UK illegally contain potent corticosteroids. Arch Dis Child. 2003 Dec;88(12):1056-7.
- Slodownik D, Nixon R; Occupational factors in skin diseases. Curr Probl Dermatol. 2007;35:173-89.
- Lupi O, Madkan V, Tyring SK; Tropical dermatology: bacterial tropical diseases. J Am Acad Dermatol. 2006 Apr;54(4):559-78; quiz 578-80.
- Lupi O, Tyring SK, McGinnis MR; Tropical dermatology: fungal tropical diseases. J Am Acad Dermatol. 2005 Dec;53(6):931-51, quiz 952-4.
- Valeyrie-Allanore L, Sassolas B, Roujeau JC; Drug-induced skin, nail and hair disorders. Drug Saf. 2007;30(11):1011-30.
- Dika E, Bardazzi F, Balestri R, et al; Environmental factors and psoriasis. Curr Probl Dermatol. 2007;35:118-35.
- Picardi A, Pasquini P, Abeni D, et al; Psychosomatic assessment of skin diseases in clinical practice. Psychother Psychosom. 2005;74(5):315-22.
- Hinds G, Thomas VD; Malignancy and cancer treatment-related hair and nail changes. Dermatol Clin. 2008 Jan;26(1):59-68, viii.
- Scully C; A review of common mucocutaneous disorders affecting the mouth and lips. Ann Acad Med Singapore. 1999 Sep;28(5):704-7.
- Bowns IR, Collins K, Walters SJ, et al; Telemedicine in dermatology: a randomised controlled trial. Health Technol Assess. 2006 Nov;10(43):iii-iv, ix-xi, 1-39.
- Bruce AJ, Brodland DG; Overview of skin cancer detection and prevention for the primary care physician. Mayo Clin Proc. 2000 May;75(5):491-500.
- Referral for Suspected Cancer CG27; NICE Guidance
- Chuh AA, Wong WC, Wong SY, et al; Procedures in primary care dermatology. Aust Fam Physician. 2005 May;34(5):347-51.
- Paraskevas LR, Halpern AC, Marghoob AA; Utility of the Wood's light: five cases from a pigmented lesion clinic. Br J Dermatol. 2005 May;152(5):1039-44.
|Original Author: Dr Chloe Borton||Current Version: Dr Chloe Borton||Peer Reviewer: Dr Huw Thomas|
|Last Checked: 17/11/2011||Document ID: 2041 Version: 25||© EMIS|
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