Abstract
Dermatology is an important aspect of primary care with 15% of consultations relating to skin complaints. This article aims to provide a useful guide to diagnosing and managing guttate psoriasis including how to differentiate it from other acute erythematous rashes. We explore the key elements of history and examination, what management strategies can be used in primary care, including the evidence for the use of antibiotics, and when to refer to secondary care.
The GP curriculum and guttate psoriasis
Manage primary contact with patients who have a skin problem Demonstrate a reasoned approach to the diagnosis of skin symptoms using history, examination, incremental investigations and referral Appreciate the importance of the social and psychological impact of skin problems on the patient's quality of life including, for example, the effects of disfigurement or sleep deprivation as a result of itching Describe the rationale for restricting certain investigations and treatments in the management of skin problems, e.g. access to phototherapy Recognize how disfigurement and cosmetic skin changes fundamentally affect patients' confidence, mood and interpersonal relationships
Background
Psoriasis is a chronic skin condition affecting about 2% of the world population. The typical history is a fluctuating course from near clearance to sudden possibly severe relapses. The aetiology is multifactorial with a strong genetic component and environmental influences, such as stress and infections. The severity of the condition also varies enormously from mild self-limiting symptoms to severe episodes requiring hospitalization. There is a wide-ranging clinical spectrum of different psoriasis phenotypes, with the plaque form accounting for 80%. Other types include palmoplantar, pustular, flexural, erythrodermic and guttate psoriasis. Guttate psoriasis is one of the less common types accounting for less than 5% of cases but requires a particular management strategy and will be the focus of the rest of this article.
Epidemiology
The name guttate is derived from the latin gutta, meaning drop, reflecting the teardrop shape of the lesions. Although any age group can be affected, it is most common in those above 10 years and below 40 years of age. Streptococcal infections are highly associated with guttate psoriasis with the rash typically erupting 1–2 weeks after the onset of symptoms. The infections are usually of the throat, but perianal infections have also been linked. Other infections have been implicated, including the herpes varicella virus.
A genetic predisposition has been reported with specific haplotypes HLA-BW17, HLA-B13 and HLA-CW6. Drugs account for some new cases and recurrences namely nonsteroidal anti-inflammatories (NSAIDS), beta blockers, anti-malarials and biological agents, including infliximab. Stress from psychological or physical causes can also prompt the eruption of the rash.
Guttate psoriasis is one of the skin conditions that demonstrate the Koebner phenomenon, which means the plaques or pustules appear at sites of injury or trauma. Generally, in psoriatic conditions, this is secondary to scratching. The Koebner phenomenon is demonstrated in several dermatological complaints as shown in Box 1.
Conditions displaying the Koebner phenomenon
Psoriasis Lichen planus Eczema Molluscum contagiosum Vitiligo Pityriasis rubra pilaris Lichen sclerosis Keratosis follicularis (Darier disease)
Cases of guttate psoriasis can increase the patient's risk of developing chronic plaque psoriasis in the future. On other occasions, guttate psoriasis is simply the initial presentation of chronic psoriasis following induction from a recognized cause, such as an infection, which then progresses. This evolution is more likely if there is a family history of psoriasis. Spontaneous resolution, however, is possible particularly in younger patients and those with a high anti-streptolysin O (ASO) titre taken at the time of the onset.
History
When patients present with an acute rash, it is necessary to take a thorough history. The time scale for the rash is important; did all lesions appear spontaneously or are they progressing and have they changed? Specific questions should include:
Location of the rash and where it started Any similar episodes in the past? Are there any relieving or exacerbating features—for instance sunlight or heat? Are there any associated symptoms including itch, tenderness, bleeding or discharge from the lesion? Any systemic features including pyrexia, malaise and weight loss? Any symptoms involving nails, hair or joint pain? Any recent infections including upper respiratory tract and diarrhoeal illness? Have any treatments been tried including over the counter, prescribed and complementary medications?
A past medical history may reveal clues to the current condition but a personal and/or family history of eczema and psoriasis should be explored. It is also important to establish if this particular rash has affected anyone else in the family. Take a full drug history with a focus on new medications and those associated with rashes including NSAIDS, antibiotics, thiazide diuretics and any known drug allergies. A smoking, alcohol and recreational drug history should also be sought as well as an occupational and travel history.
With any dermatological complaint, but particularly with psoriasis, it is important to take a psychological history. There may be psychological stress contributing to the presentation of the rash or as a direct cause in the case of dermatitis artefacta. It is important to ascertain how the patient is affected by the rash as patients may feel self-conscious causing anxiety and depression. This can lead to social withdrawal and affect education or employment.
Examination
Note the location and distribution of the rash, looking for clues to the possible aetiology. Areas out of sight to the patient should be checked, for instance, the back and areas where psoriasis can manifest including the groin, hairline and natal cleft. Areas commonly missed when examining the skin include the nails and mucosal surfaces.
Once the distribution of the rash has been established, focus on the lesions themselves and their individual features, such as colour, size, shape and surface. It is also helpful to compare them to each other for possible uniformity. If a scale is present, see if it is exacerbated with gentle scratching or if it can be lifted off. Remember to check for any lymph node involvement or joint swelling.
Presentation
The typical presentation of guttate psoriasis is an acute eruption of multiple and widespread small oval-shaped lesions. The lesions are erythematous, scaly papules and plaques (see Fig. 1). Any area on the body can be affected but the trunk and proximal limbs are usually affected, while lesions on the face are much less common (see Fig. 2). The palms and soles are typically spared. The lesions are usually similar in size ranging from 0.3 up to 1 cm. The plaques vary in number from a few to hundreds. The lesions can be itchy but are typically asymptomatic. The eruption usually occurs 1–2 weeks following a streptococcal pharyngitis.
Close up picture showing typical appearance of guttate psoriasis.
Typical distribution of guttate psoriasis.
Investigations
Guttate psoriasis is a clinical diagnosis. The shape, distribution of the lesions and history of a pharyngitis are usually enough to confirm the diagnosis. If there is clinical doubt, then serology for ASO titre can be useful and is elevated in over half of cases. Swabs and bacterial culture of the throat or perianal area can be used to confirm the presence of streptococcal organisms. A skin biopsy is not usually required but can demonstrate the typical microscopic findings of T-cell proliferation and inflammation found in guttate psoriasis.
Differential diagnosis
There is a wide list of differentials for guttate psoriasis. The most common and serious with the key similarities and differences are summarized in Table 1.
Differential diagnoses
Plaque psoriasis
The papular form of plaque psoriasis during a flare can resemble guttate psoriasis; however, there is a greater degree of scaling and erythema to the papules with plaque psoriasis and the patient may have a prior history. In plaque psoriasis, the lesions also vary in size compared with the uniformity of guttate. Plaque psoriasis is more likely to flare in relation to stress than an infective cause.
Pityriasis rosea
Like guttate psoriasis, pityriasis rosea is also thought to have an infective origin with human herpes virus-7 being implicated. The location of the lesions of pityriasis rosea is usually the trunk and proximal extremities, which can lead to some diagnostic confusion with guttate psoriasis. However, the distribution of pityriasis rosea differs by following Langer's lines giving the classic fir-like pattern.
The lesions of pityriasis rosea are oval shaped and salmon coloured, with a fine scale within the papules or plaques. The key distinguishing feature is the herald patch, a 2–3 cm diameter plaque, predating the main rash by a few days. The location of the herald patch tends to determine where the rash will appear and it is often wrongly diagnosed as ringworm due to the scaly appearance and being a single lesion. The rash of pityriasis rosea is self-limiting, resolving sooner than guttate psoriasis at around 6 weeks.
Discoid eczema
The lesions in discoid eczema tend to be larger, oval or annular scaly patches compared to the smaller tear-shaped lesions in guttate psoriasis. There may also be a crust on the surface and lesions can have a wet appearance. Typically, affected areas include the hands and arms in the young and lower limbs in older adults. There may be a history of eczema in these patients.
Lichen planus
Lichen planus presents with mauve, shiny flat papules, particularly on the flexor aspect of the wrist, that tend to be extremely itchy. The papules can be widespread over the trunk and also demonstrate the Koebner phenomenon, which can cause possible confusion with guttate psoriasis.
The white fine streaks, or Wickham's striae, that cross the surface of the lesions in lichen planus help to differentiate it from guttate psoriasis. The presence of a white lace like pattern of oral lichen planus in the mouth, if present, also helps to confirm the diagnosis. Lichen planus lasts much longer than guttate psoriasis, with lesions persisting up to 18 months.
Syphilis
Secondary syphilis can cause a widespread erythematous rash on the trunk. However, the palms and soles are often affected and a generalized lymphadenopathy and malaise are common. The patient may also have other cutaneous signs, such as condylomata lata. If required, serology testing can be used to confirm a diagnosis of syphilis.
Mycosis fungoides
Mycosis fungoides is a cutaneous T-cell lymphoma, which typically presents with pruritic erythematous scaly patches. The key difference is the varying colour of the individual patches, which may be pink, red or orangey-brown. With time, the patches form plaques and can progress to tumours. The disease process can become aggressive and spread to other organs. A biopsy is required to confirm the diagnosis and a dermatologist should manage all cases.
Pityriasis lichenoides
Pityriasis lichenoides is similar to guttate psoriasis in distribution and appearance of the rash following an upper respiratory tract infection. The colour is much more varied being browny-red or orangey though. There is a less even distribution and the rash can leave hypopigmented areas of skin. The key distinction is the mica scale, which can be easily removed, often in one piece. This is a difficult diagnosis to make and requires a skin biopsy to confirm.
Drug exanthem
A drug reaction should always be considered as a cause for a new onset rash. Skin lesions tend to be a brighter red, have less or no scaling and are more pruritic in nature. A full blood count will usually show an eosinophilia. A drug history should be taken particularly for the drugs known to exacerbate or trigger psoriasis, which include beta blockers, NSAIDs, angiotensin-converting enzyme inhibitors and anti-malarials.
Seborrhoeic eczema
A particular pattern of seborrhoeic eczema over the central chest and back can be similar in appearance to guttate psoriasis. The rash persists for more than 6 weeks and may have more classical presentations, such as nasolabial fold, eyebrow or scalp involvement.
Tinea corporis
Tinea corporis (more commonly called ringworm) also has pink scaly papules or plaques. These tend to be itchy and slowly enlarge. There are usually few lesions and they tend to be varying sizes and asymmetrical. The central clearing, due to the healing from the centre, helps distinguish ringworm from guttate psoriasis.
Primary care management
Guttate psoriasis is usually self-limiting with most episodes resolving spontaneously within a few weeks but in some patients, full resolution can take up to 4 months. Many patients will have no further episodes. The rash is often asymptomatic and a clear explanation of the diagnosis is all that is required, particularly if the patient is not concerned about the cosmetic appearance. It is important to reassure the patient that the rash is neither infective nor malignant.
Simple emollients help to retain moisture in the stratum corneum and can be used if the patient is suffering with itching or cracking of the skin. Topical treatments including mild to moderate corticosteroids, vitamin D analogues, such as calcipotriol, or coal tar preparations can also be considered for guttate psoriasis. There is no clear evidence which of these treatments is most beneficial so the decision regarding treatment should be based on past experience and patient preference. The use of these preparations is limited by difficulty in applying to all lesions, which can be awkward and time consuming.
The use of antimicrobials remains commonplace in primary care and by dermatologists; however, there is limited supporting evidence. A Cochrane review found no convincing evidence of the benefit of antibiotics in either treating established guttate psoriasis or preventing its occurrence following a streptococcal throat infection (Owen et al., 2000). The review was limited by the paucity of studies, with only one being accepted as eligible. Clinical Knowledge Summary (2010) does not support the use of anti-streptococcal antibiotics either in acute guttate psoriasis or in recurrences and a recent study comparing phenoxymethylpenicillin, erythromycin and placebo for the treatment of guttate psoriasis found no significant differences at 4 weeks between the different treatment groups (Dogan et al., 2008).
Referral
Refer patients with widespread guttate psoriasis urgently to a dermatologist for consideration of phototherapy [National Institute for Health and Clinical Excellence (NICE, 2001; British Association of Dermatologists, 2004)]. Referral to an ear, nose and throat specialist for tonsillectomy should be considered for recurrent episodes of guttate psoriasis, which are linked with well-documented episodes of tonsillitis. The evidence for this procedure is mixed, with a Cochrane review finding no evidence of benefit (Owen et al., 2000), but tonsillectomy is supported by the British Association of Dermatologists (2004). Referral to a dermatologist may be required if the patient has significant social or psychological issues related to their psoriasis and if symptoms are affecting sleep, employment or education.
Key points
Guttate psoriasis presents with a sudden onset rash of erythematous, scaly drop-like lesions typically following a streptococcal pharyngitis Clinical diagnosis is based on the appearance and distribution of lesions Use of antibiotics against streptococcal bacteria is not supported by evidence Topical treatments including corticosteroids, vitamin D analogues or coal tar preparations can be used to treat symptoms according to patient preference An urgent dermatology referral, for consideration of phototherapy, should be considered if lesions are widespread
Footnotes
Acknowledgements
I would like to thank Dr Emma Harris for her help with the writing of this article under the InnovAiT ‘buddy’ scheme.