Diagnostic Testing for Lichen Planus: Understanding Skin Patch Testing, Skin Prick Testing, and RAST

Lichen planus is a clinical diagnosis that can be made based on the characteristic appearance of the rash. However, in some cases, a biopsy may be helpful if the presentation is atypical. The diagnosis is typically made without the need for further testing, and treatment can be started promptly.

Skin patch testing and skin prick testing are not useful for diagnosing lichen planus, as they are mainly used for different types of hypersensitivity reactions. Skin patch testing is used for contact dermatitis and other type IV hypersensitivity reactions, while skin prick testing is used for type I hypersensitivity reactions, such as food allergies and pollen allergies.

Radioallergosorbent testing (RAST) is also unsuitable for diagnosing lichen planus, as it is used to determine the amount of immunoglobulin E (IgE) that reacts specifically with suspected or known allergens. RAST is useful for food allergies, inhaled allergens (such as pollen), and wasp/bee venom.

In summary, diagnostic testing is not typically required for lichen planus, as it can be diagnosed clinically. Skin patch testing, skin prick testing, and RAST are not useful for diagnosing lichen planus and are mainly used for different types of hypersensitivity reactions.

Eczema herpeticum is a skin infection primarily caused by herpes simplex virus (HSV) and, in rare cases, coxsackievirus. Herpes zoster leads to chickenpox, roseola is caused by HHV 6, and molluscum contagiosum is caused by poxvirus.

Understanding Eczema Herpeticum

Eczema herpeticum is a serious skin infection caused by herpes simplex virus 1 or 2. It is commonly observed in children with atopic eczema and is characterized by a rapidly progressing painful rash. The infection can be life-threatening, which is why it is important to seek medical attention immediately.

During examination, doctors typically observe monomorphic punched-out erosions, which are circular, depressed, and ulcerated lesions that are usually 1-3 mm in diameter. Due to the severity of the infection, children with eczema herpeticum should be admitted to the hospital for intravenous aciclovir treatment. It is important to understand the symptoms and seek medical attention promptly to prevent any complications.

The patient exhibits typical signs of a venous ulcer and appears to be in good overall health without any indications of infection. The recommended treatment for venous ulcers involves the use of compression dressings, but it is crucial to ensure that the patient’s arterial circulation is sufficient to tolerate some level of compression.

Venous Ulceration and its Management

Venous ulceration is a type of ulcer that is commonly seen above the medial malleolus. To assess for poor arterial flow that could impair healing, an ankle-brachial pressure index (ABPI) is important in non-healing ulcers. A normal ABPI is usually between 0.9 – 1.2, while values below 0.9 indicate arterial disease. Interestingly, values above 1.3 may also indicate arterial disease, particularly in diabetics, due to false-negative results caused by arterial calcification.

The only treatment that has been shown to be of real benefit for venous ulceration is compression bandaging, usually four-layer. Oral pentoxifylline, a peripheral vasodilator, can also improve the healing rate. There is some small evidence supporting the use of flavonoids, but little evidence to suggest benefit from hydrocolloid dressings, topical growth factors, ultrasound therapy, and intermittent pneumatic compression. Proper management of venous ulceration is crucial to promote healing and prevent complications.

Common Skin Hypersensitivity Reactions and their Causes

Skin hypersensitivity reactions can range from mild to life-threatening. Here are some common types and their causes:

Toxic Epidermal Necrolysis: This is the most serious skin hypersensitivity reaction, with a high mortality rate. It is usually caused by drugs such as NSAIDs, steroids, methotrexate, allopurinol and penicillins.

Erythema Multiforme: This is a target-like lesion that commonly occurs on the palms and soles. It is usually caused by drugs such as penicillins, phenytoin, NSAIDs and sulfa drugs. Mycoplasma and herpes simplex infections can also cause erythema multiforme.

Erythema Nodosum: This is an inflammatory condition of subcutaneous tissue. The most common causes are recent streptococcal infection, sarcoidosis, tuberculosis and inflammatory bowel disease.

Fixed Drug Reaction: This is a localised allergic drug reaction that recurs at the same anatomic site of the skin with repeated drug exposure. It is most commonly caused by aspirin, NSAIDs, tetracycline and barbiturate.

Morbilliform Rash: This is a mild hypersensitivity skin reaction that manifests as a generalised maculopapular eruption that blanches with pressure. The rash can be caused by penicillin, sulfa drugs, allopurinol and phenytoin.

When differentiating between spider naevi and telangiectasia, it is important to note that spider naevi fill from the centre when pressed, while telangiectasia fill from the edge. A woman presenting with a small lesion surrounded by tiny blood vessels radiating from the middle that refills from the centre is likely to have a spider naevus. This condition is commonly associated with liver failure, making it the most likely diagnosis.

Understanding Spider Naevi

Spider naevi, also known as spider angiomas, are characterized by a central red papule surrounded by capillaries. These lesions can be identified by their ability to blanch upon pressure. Spider naevi are typically found on the upper part of the body and are more common in childhood, affecting around 10-15% of people.

To differentiate spider naevi from telangiectasia, one can press on the lesion and observe how it fills. Spider naevi fill from the center, while telangiectasia fills from the edge. It is important to note that spider naevi may be associated with liver disease, pregnancy, and the use of combined oral contraceptive pills.

In summary, understanding spider naevi is important for proper diagnosis and management. By recognizing their distinct characteristics and potential associations, healthcare professionals can provide appropriate care for their patients.

Blistering is not a characteristic of polymorphic eruption of pregnancy.

Skin Disorders Associated with Pregnancy

During pregnancy, women may experience various skin disorders. The most common one is atopic eruption of pregnancy, which is characterized by an itchy red rash. This condition does not require any specific treatment. Another skin disorder is polymorphic eruption of pregnancy, which is a pruritic condition that usually appears during the last trimester. The lesions often first appear in abdominal striae, and management depends on the severity of the condition. Emollients, mild potency topical steroids, and oral steroids may be used. Pemphigoid gestationis is another skin disorder that causes pruritic blistering lesions. It usually develops in the peri-umbilical region and later spreads to the trunk, back, buttocks, and arms. This condition is rarely seen in the first pregnancy and usually presents in the second or third trimester. Oral corticosteroids are usually required for treatment.

While acanthosis nigricans may occur on its own in individuals with dark skin, it is typically a sign of insulin resistance and associated conditions such as type 2 diabetes, polycystic ovarian syndrome, Cushing’s syndrome, and hypothyroidism. Certain medications, including corticosteroids, insulin, and hormone medications, can also cause this condition. If acanthosis nigricans appears suddenly and in unusual areas such as the mouth, it may indicate the presence of an internal malignancy, particularly gastric cancer.

Acanthosis nigricans is a condition characterized by the presence of symmetrical, brown, velvety plaques on the neck, axilla, and groin. This condition can be caused by various factors such as type 2 diabetes mellitus, gastrointestinal cancer, obesity, polycystic ovarian syndrome, acromegaly, Cushing’s disease, hypothyroidism, familial factors, Prader-Willi syndrome, and certain drugs like the combined oral contraceptive pill and nicotinic acid. The pathophysiology of acanthosis nigricans involves insulin resistance, which leads to hyperinsulinemia. This, in turn, stimulates the proliferation of keratinocytes and dermal fibroblasts through interaction with insulin-like growth factor receptor-1 (IGFR1).

IV antivirals are necessary for the treatment of eczema herpeticum, which is a severe condition.

Understanding Eczema Herpeticum

Eczema herpeticum is a serious skin infection caused by herpes simplex virus 1 or 2. It is commonly observed in children with atopic eczema and is characterized by a rapidly progressing painful rash. The infection can be life-threatening, which is why it is important to seek medical attention immediately.

During examination, doctors typically observe monomorphic punched-out erosions, which are circular, depressed, and ulcerated lesions that are usually 1-3 mm in diameter. Due to the severity of the infection, children with eczema herpeticum should be admitted to the hospital for intravenous aciclovir treatment. It is important to understand the symptoms and seek medical attention promptly to prevent any complications.

Understanding Rosacea: Symptoms and Management

Rosacea, also known as acne rosacea, is a chronic skin condition that has no known cause. It typically affects the nose, cheeks, and forehead, and the first symptom is often flushing. Over time, telangiectasia (visible blood vessels) may appear, followed by persistent redness with papules and pustules. In some cases, rhinophyma (enlarged nose) may develop, and there may be ocular involvement, such as blepharitis. Sunlight can exacerbate symptoms.

Mild cases of rosacea may be treated with topical metronidazole, while topical brimonidine gel may be used for patients with predominant flushing but limited telangiectasia. More severe cases may require systemic antibiotics like oxytetracycline. Patients are advised to apply high-factor sunscreen daily and use camouflage creams to conceal redness. Laser therapy may be appropriate for those with prominent telangiectasia, and patients with rhinophyma should be referred to a dermatologist.

Overall, understanding the symptoms and management of rosacea can help individuals manage their condition and improve their quality of life.

Management of Erythroderma in an Elderly Patient Living Alone

Erythroderma is a dermatological emergency that requires urgent treatment. In elderly patients who are frail and live alone, hospital admission is necessary. This is the case for an 86-year-old man with a history of psoriasis who presents with erythroderma. Topical emollients and steroids are key in management, but this patient requires intravenous fluids and close monitoring for infection and dehydration. Oral antibiotics are not indicated unless there are signs of infection. A topical steroid with a vitamin D analogue may be appropriate for psoriasis, but urgent assessment by Dermatology in an inpatient setting is necessary. An outpatient appointment is not appropriate for this patient due to his age and living situation.

Lichen planus is a skin condition characterized by a rash of purple, itchy, polygonal papules on the flexor surfaces of the body. The affected area may also have Wickham’s striae. Oral involvement is common. In addition, elderly women may experience itchy white spots on the vulva, known as lichen sclerosus. Mucous membrane involvement is also frequently observed in lichen planus.

Understanding Lichen Planus

Lichen planus is a skin condition that is believed to be caused by an immune response, although the exact cause is unknown. It is characterized by an itchy, papular rash that typically appears on the palms, soles, genitalia, and flexor surfaces of the arms. The rash often has a polygonal shape and a distinctive white-lines pattern on the surface, known as Wickham’s striae. In some cases, new skin lesions may appear at the site of trauma, a phenomenon known as the Koebner phenomenon.

Oral involvement is common in around 50% of patients, with a white-lace pattern often appearing on the buccal mucosa. Nail changes may also occur, including thinning of the nail plate and longitudinal ridging. Lichenoid drug eruptions can be caused by certain medications, such as gold, quinine, and thiazides.

The main treatment for lichen planus is potent topical steroids. For oral lichen planus, benzydamine mouthwash or spray is recommended. In more extensive cases, oral steroids or immunosuppression may be necessary.

The relevant diagnosis for this question relies solely on the description of the lesions, as the patient’s medical history is not a factor. Specifically, the tender shin lesions are indicative of erythema nodosum.

Understanding Shin Lesions: Differential Diagnosis and Characteristic Features

Shin lesions can be caused by a variety of conditions, and it is important to differentiate between them in order to provide appropriate treatment. The four most common conditions that can cause shin lesions are erythema nodosum, pretibial myxoedema, pyoderma gangrenosum, and necrobiosis lipoidica diabeticorum.

Erythema nodosum is characterized by symmetrical, tender, erythematous nodules that heal without scarring. It is often caused by streptococcal infections, sarcoidosis, inflammatory bowel disease, or certain medications such as penicillins, sulphonamides, or oral contraceptive pills.

Pretibial myxoedema, on the other hand, is seen in Graves’ disease and is characterized by symmetrical, erythematous lesions that give the skin a shiny, orange peel appearance.

Pyoderma gangrenosum initially presents as a small red papule, which later develops into deep, red, necrotic ulcers with a violaceous border. It is idiopathic in 50% of cases, but may also be seen in inflammatory bowel disease, connective tissue disorders, and myeloproliferative disorders.

Finally, necrobiosis lipoidica diabeticorum is characterized by shiny, painless areas of yellow/red skin typically found on the shin of diabetics. It is often associated with telangiectasia.

In summary, understanding the differential diagnosis and characteristic features of shin lesions can help healthcare professionals provide appropriate treatment and improve patient outcomes.

Treatment Options for chickenpox in Children

chickenpox is a common viral infection in children that presents with a characteristic vesicular rash. While there is no specific treatment for chickenpox, symptomatic relief can be provided to alleviate itching and fever. Here are some treatment options for chickenpox in children:

1. Chlorphenamine: This sedating antihistamine can be used at night-time to help with itching.

2. Aciclovir: This antiviral medication is recommended for patients who are immunosuppressed or have risk factors for developing complications from infection, such as adults or newborns.

3. Flucloxacillin: This antibiotic is used to treat secondary bacterial infections that can occur with chickenpox. However, it is not necessary for a child who is well and afebrile.

4. Ibuprofen: While ibuprofen and paracetamol are both used as antipyretics in children with febrile illnesses, the use of ibuprofen in children with chickenpox is linked to an increased risk of severe skin infection. Paracetamol is recommended instead.

5. Malathion: This treatment is for scabies, not chickenpox. Scabies presents with a different type of rash and does not have a prodromal illness.

In summary, treatment for chickenpox in children is mainly symptomatic. Antihistamines and calamine lotion can help with itching, while paracetamol can be used for fever. Antibiotics and antivirals are only necessary in certain cases.

Common Skin Lesions and Cancers: Characteristics and Clinical Presentations

Squamous cell carcinoma (SCC), actinic keratosis, Bowen’s disease, cold sores, and leukoplakia are common skin lesions and cancers that have distinct characteristics and clinical presentations.

SCC is a malignant tumour that commonly affects the backs of the hands and forearms, the upper part of the face, and the lower lip and pinna in men. The first clinical sign is induration, which may take on nodular, plaque-like, verrucous, or ulcerated characteristics. The limits of induration are not sharp and usually extend beyond the visible margins of the lesion. The surrounding tissue is often inflamed. SCCs rarely metastasize.

Actinic keratosis is a sun-induced scaly or hyperkeratotic lesion that has the potential to become malignant. It is characterized by multifocal, scaly, hyperpigmented or scaly lesions, usually brown with a scaly base, occurring on the head, neck, forearms, and hands.

Bowen’s disease is an intraepidermal (in situ) squamous cell carcinoma that arises in sun-exposed sites, especially the lower legs in women. It is characterized by well-defined pink and scaly patches or plaques that may become crusty, fissured, or ulcerated as lesions grow.

Cold sores are recurrent infections of orofacial herpes simplex that present as grouped vesicles, especially of the lips and perioral skin. The eruption is often preceded by a tingling, itching, or burning sensation. Over a few days, the vesicles form a crust, and the eruption resolves within 7–10 days.

Leukoplakia is a white patch or plaque of the oral mucosa that cannot be characterized clinically or pathologically as any other condition.

A non-healing lesion is also of concern, especially in patients with a history of smoking and advanced age, as it may indicate a malignant cause. Early detection and treatment are crucial in preventing the progression of these skin lesions and cancers.

Understanding Autoimmune Blistering Conditions: Pemphigus Vulgaris and Bullous Pemphigoid

Pemphigus Vulgaris: Autoimmune Blistering Condition

Pemphigus vulgaris is an autoimmune blistering condition that primarily affects middle-aged patients. The condition is caused by Immunoglobulin G (IgG) autoantibodies against desmosomal components (desmogleins 1 and 3) of the superficial layers of the skin. This results in flaccid blisters that rupture easily, leading to erosions and scarring. The oral mucosa is often affected early, and Nikolsky’s sign is positive. Immunofluorescence reveals intra-epidermal circular deposits, and antibodies against desmosomes are usually positive. The condition requires aggressive treatment, with high-dose steroids initially used, and life-long maintenance doses often needed. Immunologicals are being trialled.

Bullous Pemphigoid: Another Autoimmune Blistering Condition

Bullous pemphigoid is another autoimmune blistering condition that typically affects older patients. The condition is caused by antibodies directed to the deeper basement membrane of the skin. This results in tense, firm, often haemorrhagic blisters that do not rupture easily. Oral lesions are rare, and Nikolsky’s sign is negative. Immunofluorescence reveals linear IgG and C3 deposits along the basement membrane of the skin, and antibodies against hemidesmosomes may be positive. The condition carries significantly less morbidity than pemphigus vulgaris, and topical steroid cream (ex: clobetasol propionate usually suffices).

No Link to Other Conditions

There is no link between pemphigus vulgaris or bullous pemphigoid and other conditions such as alopecia, positive HIV serology, or psoriasis. It is important to understand the differences between these autoimmune blistering conditions to ensure proper diagnosis and treatment.

The skin patch test can be beneficial in this scenario as it has the potential to detect irritants in addition to allergens.

Types of Allergy Tests

Allergy tests are used to determine if a person has an allergic reaction to a particular substance. There are several types of allergy tests available, each with its own advantages and limitations. The most commonly used test is the skin prick test, which is easy to perform and inexpensive. Drops of diluted allergen are placed on the skin, and a needle is used to pierce the skin. A wheal will typically develop if a patient has an allergy. This test is useful for food allergies and pollen.

Another type of allergy test is the radioallergosorbent test (RAST), which determines the amount of IgE that reacts specifically with suspected or known allergens. Results are given in grades from 0 (negative) to 6 (strongly positive). This test is useful for food allergies, inhaled allergens (e.g. pollen), and wasp/bee venom.

Skin patch testing is useful for contact dermatitis. Around 30-40 allergens are placed on the back, and irritants may also be tested for. The patches are removed 48 hours later, and the results are read by a dermatologist after a further 48 hours. Blood tests may be used when skin prick tests are not suitable, for example if there is extensive eczema or if the patient is taking antihistamines. Overall, allergy tests are an important tool in diagnosing and managing allergies.

Psoriasis and Psoriatic Arthropathy: Nail Changes

Psoriasis is a skin condition that can also affect the nails. The changes in the nails do not necessarily indicate the severity of psoriasis, but they are often associated with psoriatic arthropathy. In fact, around 80-90% of patients with psoriatic arthropathy have nail changes.

The nail changes that may occur in psoriasis include pitting, onycholysis (separation of the nail from the nail bed), subungual hyperkeratosis, and loss of the nail. These changes can affect both the fingers and toes. It is important to note that while nail changes may not be a reliable indicator of psoriasis severity, they can be a sign of psoriatic arthropathy, which is a type of arthritis that can occur in people with psoriasis.

As a first-line treatment, NICE suggests using a strong corticosteroid and a vitamin D analogue separately, once a day for up to four weeks. The corticosteroid should be applied in the morning and the vitamin D analogue in the evening.

NICE recommends a step-wise approach for chronic plaque psoriasis, starting with regular emollients and then using a potent corticosteroid and vitamin D analogue separately, followed by a vitamin D analogue twice daily, and then a potent corticosteroid or coal tar preparation if there is no improvement. Phototherapy, systemic therapy, and topical treatments are also options for management. Topical steroids should be used cautiously and vitamin D analogues may be used long-term. Dithranol and coal tar have adverse effects but can be effective.

Tear-drop scaly papules suddenly appearing on the trunk and limbs may indicate guttate psoriasis.

Guttate psoriasis is a type of psoriasis that is more commonly seen in children and adolescents. It is often triggered by a streptococcal infection that occurred 2-4 weeks prior to the appearance of the lesions. The name guttate comes from the Latin word for drop, as the lesions appear as small, tear-shaped papules on the trunk and limbs. These papules are pink and scaly, and the onset of the condition is usually acute, occurring over a few days.

In most cases, guttate psoriasis will resolve on its own within 2-3 months. There is no clear evidence to support the use of antibiotics to treat the underlying streptococcal infection. Treatment options for guttate psoriasis include topical agents commonly used for psoriasis and UVB phototherapy. In cases where the condition recurs, a tonsillectomy may be necessary.

It is important to differentiate guttate psoriasis from pityriasis rosea, another skin condition that can present with similar symptoms. Guttate psoriasis is often preceded by a streptococcal sore throat, while pityriasis rosea may be preceded by a respiratory tract infection. The appearance of guttate psoriasis is characterized by tear-shaped papules on the trunk and limbs, while pityriasis rosea presents with a herald patch followed by multiple oval lesions with a fine scale. While guttate psoriasis resolves within a few months, pityriasis rosea typically resolves after around 6 weeks.

Compression bandaging is recommended for the management of venous ulceration, as the ankle-brachial pressure index readings suggest that the ulcers are caused by venous insufficiency rather than arterial issues.

Venous Ulceration and its Management

Venous ulceration is a type of ulcer that is commonly seen above the medial malleolus. To assess for poor arterial flow that could impair healing, an ankle-brachial pressure index (ABPI) is important in non-healing ulcers. A normal ABPI is usually between 0.9 – 1.2, while values below 0.9 indicate arterial disease. Interestingly, values above 1.3 may also indicate arterial disease, particularly in diabetics, due to false-negative results caused by arterial calcification.

The only treatment that has been shown to be of real benefit for venous ulceration is compression bandaging, usually four-layer. Oral pentoxifylline, a peripheral vasodilator, can also improve the healing rate. There is some small evidence supporting the use of flavonoids, but little evidence to suggest benefit from hydrocolloid dressings, topical growth factors, ultrasound therapy, and intermittent pneumatic compression. Proper management of venous ulceration is crucial to promote healing and prevent complications.