Kaposi’s sarcoma (KS) is a type of cancer that affects the connective tissues. It is caused by a virus called human herpesvirus 8 (HHV-8). This cancer is more likely to occur in individuals with weakened immune systems, such as those with HIV or those who have undergone organ transplants.

The main symptom of KS is the development of skin lesions. These lesions initially appear as red-purple spots and quickly progress to become raised bumps and nodules. They can appear on any part of the body, but are most commonly found on the lower limbs, back, face, mouth, and genital area.

Bullous pemphigoid (BP) is a chronic autoimmune disorder that affects the skin, causing blistering. It occurs when the immune system mistakenly attacks the basement membrane of the epidermis. This attack is carried out by immunoglobulins (IgG and sometimes IgE) and activated T lymphocytes. The autoantibodies bind to proteins and release cytokines, leading to complement activation, neutrophil recruitment, and the release of enzymes that destroy the hemidesmosomes. As a result, subepidermal blisters form.

Pemphigus, on the other hand, is a group of autoimmune disorders characterized by blistering of the skin and mucosal surfaces. The most common type, pemphigus vulgaris (PV), accounts for about 70% of cases worldwide. PV is also autoimmune in nature, with autoantibodies targeting cell surface antigens on keratinocytes (desmogleins 1 and 3). This leads to a loss of adhesion between cells and their separation.

Here is a comparison of the key differences between pemphigus vulgaris and bullous pemphigoid:

Pemphigus vulgaris:
– Age: Middle-aged people (average age 50)
– Oral involvement: Common
– Blister type: Large, flaccid, and painful
– Blister content: Fluid-filled, often haemorrhagic
– Areas commonly affected: Initially face and scalp, then spread to the chest and back
– Nikolsky sign: Usually positive
– Pruritus: Rare
– Skin biopsy: Intra-epidermal deposition of IgG between cells throughout the epidermis

Bullous pemphigoid:
– Age: Elderly people (average age 80)
– Oral involvement: Rare
– Blister type: Large and tense
– Blister content: Fluid-filled
– Areas commonly affected: Upper arms, thighs, and skin flexures
– Nikolsky sign: Usually negative
– Pruritus: Common
– Skin biopsy: A band of IgG and/or C3 at the dermo-epidermal junction

Atopic dermatitis is a long-lasting inflammatory skin condition that is linked to increased levels of IgE in the bloodstream. It is also characterized by sensitivity to various allergens found in the air, food, and microorganisms.

Further Reading:

Eczema is a chronic inflammatory skin disease characterized by dry, itchy skin with eczematous lesions. It often follows a chronic relapsing course and can lead to chronic skin changes such as lichenification and pigment changes. The term eczema is often used interchangeably with dermatitis, but strictly speaking, dermatitis refers to inflammation of the skin while eczema refers to specific conditions where skin inflammation is a feature.

Atopic eczema, also known as atopic dermatitis, is the most common type of eczema. It is usually first diagnosed in young children, with 90% of cases diagnosed before the age of 5. However, it can affect individuals of any age. Symptoms often improve as patients progress into their teens and adulthood. Around 10-20% of children are affected by atopic eczema, but only 3% of adults experience symptoms.

The exact cause of atopic eczema is not fully understood, but it is believed to be multifactorial, with both genetic and environmental factors playing a role. Genetic defects in genes that aid in the functioning of the skin barrier have been identified, which may predispose individuals to breaks in the skin barrier and increased exposure to antigens. Environmental factors such as pollution, allergen exposure, climate, and others also contribute to the development of the disease.

Diagnosing atopic eczema involves assessing the presence of key clinical features, such as pruritus (itching), eczema/dermatitis in a pattern appropriate for age, early age of onset, and personal or family history of atopy. Various diagnostic criteria have been established to aid in the diagnosis, including those set out by the American Academy of Dermatology and the UK working party.

The severity of atopic eczema can vary, and treatment options depend on the severity. Mild cases may be managed with emollients (moisturizers) and mild potency topical corticosteroids. Moderate cases may require moderate potency topical corticosteroids, topical calcineurin inhibitors, and bandages. Severe cases may necessitate the use of potent topical corticosteroids, topical calcineurin inhibitors, bandages, phototherapy, and systemic therapy.

In addition to medical treatment, identifying and avoiding triggers is an important aspect of managing atopic eczema. Common triggers include irritants, contact allergens, certain foods, skin infections, inhalant triggers, stress and infection.

Erythema ab igne is a condition that is frequently observed in older individuals. It typically occurs when they spend extended periods of time near a fire or utilize a hot water bottle in an attempt to relieve pain symptoms. This condition arises due to the harmful effects of heat on the skin, resulting in the appearance of reddened and pigmented areas. Fortunately, erythema ab igne tends to resolve on its own without any specific treatment.

Eczema herpeticum occurs when an individual with atopic eczema comes into contact with the herpes simplex virus. While some patients may only experience typical cold sores, others may develop a more extensive infection. This condition is often accompanied by systemic disturbance and can be quite painful. Administering antiviral treatment can help reduce the duration of the illness. In cases where the rash is widespread or there are concerns about eye complications, hospital admission may be necessary for intravenous antiviral therapy.

Chickenpox is a highly contagious illness caused by the varicella-zoster virus, a DNA virus from the Herpesviridae family. Most cases are mild to moderate, and the infection usually resolves on its own. Severe complications are rare but can occur, especially in individuals with weakened immune systems or underlying health conditions.

The incubation period for chickenpox is typically between 14 to 21 days. It is contagious from a few days before the rash appears until about a week after the first lesions show up.

The common clinical features of chickenpox include:

– Fever, which lasts for approximately 3-5 days.
– The initial rash starts as flat red spots and progresses into raised bumps.
– These bumps then turn into fluid-filled blisters and eventually form pustules surrounded by redness.
– The lesions are extremely itchy.
– The rash reaches its peak around 48 hours in individuals with a healthy immune system.
– The rash tends to be more concentrated on the face and trunk, with fewer lesions on the limbs.
– The blisters eventually dry up and form crusts, which can lead to scarring if scratched.
– Headache, fatigue, and abdominal pain may also occur.

Chickenpox tends to be more severe in teenagers and adults compared to children. Antiviral treatment should be considered for these individuals if they seek medical attention within 24 hours of rash onset. The recommended oral dose of aciclovir is 800 mg taken five times a day for seven days.

Immunocompromised patients and those at higher risk, such as individuals with severe cardiovascular or respiratory disease or chronic skin disorders, should receive antiviral treatment for ten days, with at least seven days of intravenous administration.

Although most cases are relatively mild, if serious complications like pneumonia, encephalitis, or dehydration are suspected, it is important to refer the patient for hospital admission.

For more information, you can refer to the NICE Clinical Knowledge Summary on Chickenpox.
https://cks.nice.org.uk/topics/chickenpox/

The explanation states that the increased activity of the enzyme kininogenase is caused by hormonal factors, specifically oestrogen, as well as genetic factors.

Further Reading:

Angioedema and urticaria are related conditions that involve swelling in different layers of tissue. Angioedema refers to swelling in the deeper layers of tissue, such as the lips and eyelids, while urticaria, also known as hives, refers to swelling in the epidermal skin layers, resulting in raised red areas of skin with itching. These conditions often coexist and may have a common underlying cause.

Angioedema can be classified into allergic and non-allergic types. Allergic angioedema is the most common type and is usually triggered by an allergic reaction, such as to certain medications like penicillins and NSAIDs. Non-allergic angioedema has multiple subtypes and can be caused by factors such as certain medications, including ACE inhibitors, or underlying conditions like hereditary angioedema (HAE) or acquired angioedema.

HAE is an autosomal dominant disease characterized by a deficiency of C1 esterase inhibitor. It typically presents in childhood and can be inherited or acquired as a result of certain disorders like lymphoma or systemic lupus erythematosus. Acquired angioedema may have similar clinical features to HAE but is caused by acquired deficiencies of C1 esterase inhibitor due to autoimmune or lymphoproliferative disorders.

The management of urticaria and allergic angioedema focuses on ensuring the airway remains open and addressing any identifiable triggers. In mild cases without airway compromise, patients may be advised that symptoms will resolve without treatment. Non-sedating antihistamines can be used for up to 6 weeks to relieve symptoms. Severe cases of urticaria may require systemic corticosteroids in addition to antihistamines. In moderate to severe attacks of allergic angioedema, intramuscular epinephrine may be considered.

The management of HAE involves treating the underlying deficiency of C1 esterase inhibitor. This can be done through the administration of C1 esterase inhibitor, bradykinin receptor antagonists, or fresh frozen plasma transfusion, which contains C1 inhibitor.

In summary, angioedema and urticaria are related conditions involving swelling in different layers of tissue. They can coexist and may have a common underlying cause. Management involves addressing triggers, using antihistamines, and in severe cases, systemic corticosteroids or other specific treatments for HAE.

Pityriasis versicolor, also known as tinea versicolor, is a common skin condition caused by an infection with the yeasts Malassezia furfur and Malassezia globosa. It typically presents as multiple patches of altered pigmentation, primarily on the trunk. In individuals with fair skin, these patches are usually darker in color, while in those with darker skin or a tan, they may appear lighter (known as pityriasis versicolor alba). It is not uncommon for the rash to cause itching.

The recommended treatment for pityriasis versicolor involves the use of antifungal agents. One particularly effective option is ketoconazole shampoo, which is sold under the brand name Nizoral. To use this shampoo, it should be applied to the affected areas and left on for approximately five minutes before being rinsed off. This process should be repeated daily for a total of five days.

Pemphigus, derived from the Greek word for bubble ‘pemphix’, refers to a group of autoimmune disorders that cause blistering of the skin and/or mucosal surfaces. The most common subset is pemphigus vulgaris (PV), which accounts for approximately 70% of cases worldwide. PV is characterized by an autoimmune response where autoantibodies target cell surface antigens on keratinocytes, specifically desmogleins 1 and 3. This leads to a loss of cell-to-cell adhesion and separation, resulting in blister formation.

On the other hand, bullous pemphigoid (BP) is a chronic autoimmune blistering skin disorder that affects the subepidermal layer. It occurs when the basement membrane of the epidermis is attacked by IgG and sometimes IgE immunoglobulins, as well as activated T lymphocytes. The binding of autoantibodies to proteins and the release of cytokines from T cells trigger complement activation, neutrophil recruitment, and the release of proteolytic enzymes. These enzymes destroy the hemidesmosomes, leading to the formation of subepidermal blisters.

To summarize the differences between pemphigus vulgaris and bullous pemphigoid, the following provides a comparison:

Pemphigus Vulgaris:
– Age: Middle-aged people (mean age 50)
– Oral involvement: Common
– Blister type: Large, flaccid, and painful
– Blister content: Fluid-filled, often haemorrhagic
– Areas commonly affected: Initially face and scalp, then spread to the chest and back
– Nikolsky sign: Usually positive
– Pruritus: Rare
– Skin biopsy: Intra-epidermal deposition of IgG between cells throughout the epidermis

Bullous Pemphigoid:
– Age: Elderly people (mean age 80)
– Oral involvement: Rare
– Blister type: Large and tense
– Blister content: Fluid-filled
– Areas commonly affected: Upper arms, thighs, and skin flexures
– Nikolsky sign: Usually negative
– Pruritus: Common
– Skin biopsy: A band of IgG and/or C3 at the dermo-epidermal junction

Onchocerciasis is a parasitic disease caused by the filarial nematode Onchocerca volvulus. It is transmitted through the bites of infected blackflies of Simulium species, which carry immature larval forms of the parasite from human to human.

In the human body, the larvae form nodules in the subcutaneous tissue, where they mature to adult worms. After mating, the female adult worm can release up to 1000 microfilariae a day.

Onchocerciasis is currently endemic in 30 African countries, Yemen, and a few isolated regions of South America. Approximately 37 million people worldwide are currently infected.

Symptoms start to occur around a year after the patient is infected. The earliest symptom is usually an intensely itchy rash. Various skin manifestations occur, including scattered, red, pruritic papules (acute papular onchodermatitis), larger, chronic, hyperpigmented papules (chronic papular onchodermatitis), lichenified, oedematous, hyperpigmented papules and plaques (lichenified onchodermatitis), areas of skin atrophy with loss of elasticity (‘Lizard skin’), and depigmented areas with a ‘leopard skin’ appearance, usually on the shins.

Ocular involvement provides the common name associated with onchocerciasis, river blindness, and it can involve any part of the eye. Almost a million people worldwide have at least a partial degree of vision loss caused by onchocerciasis. Initially, there may be intense watering, a foreign body sensation, and photophobia. This can progress to conjunctivitis, iridocyclitis, and chorioretinitis. Secondary glaucoma and optic atrophy may also occur.

In a number of countries, onchocerciasis has been controlled through the spraying of blackfly breeding sites with insecticide. The drug ivermectin is the preferred treatment for onchocerciasis.