URTICARIA

INTRODUCTION:
  • Urticaria is a vascular reaction pattern characterised by transient, erythematous, oedematous papules or plaques (wheals) of varying sizes and shapes which are usually pruritic.
  • Angioedema is the same process but involves the deep dermis, subcutaneous and submucosal tissues
  • Urticaria — dermal edema
  • Angioedema — subcutaneous, submucosal edema
  • Result of histamine release from mast cells in the skin.
  • Type I hypersensitivity mediated by histamine.
  • Lesions are itchy, red papules and plaques of variable size that arise suddenly, often within a few minutes
  • Recurring urticaria are SLE associated rashes
  • Investigation done for the diagnosis of itchy tense blisters on normal looking skin and urticarial rash is Direct immunofluorescence
  • Recurrent episodes of flexural exzema contact urticaria is seen in Atopic dermatitis
PRECIPITATING FACTORS:
  • Exercise/Physical exertion
  • Emotion upset
  • Exposure to sun/heat
  • Hot bath/food
THE 'PHYSICAL' URTICARIAS
  • Cold urticaria
  • Occur after exposure to the cold.
  • The reaction can be elicited by an ice block.
  • There is a familial form. 
  • Image result for Cold urticaria
Pressure urticaria
  • Lesions develop some time (up to several hours) after pressure on the skin
  • For example from belts or other tight clothing, or from the rungs of a ladder.
  • Image result for pressure urticaria
Dermographism
  • Many patients with urticaria mark easily when their skin is rubbed firmly, for example with a key.
  • This is an exaggerated 'triple response' and is quite troublesome to some patients
  • It is not influenced by an atopic diathesis a.nd has a duration of less than 5 years.
  • Image result for Dermographism
Solar urticaria
  • Urticaria spots develop on exposed skin a few minutes after exposure to the sun. It is a skin sign of one systemic disease— erythropoietic protoporphyria
  • Solar urticaria is characterized by Wheal formation
  • Almost all cases of Solar urticaria are idiopathic
  • In Solar urticaria Some cases may develop severe urticaria/bronchospasm.
  • Solar urticaria Lesions subsides spontaneously on avoiding exposure within 24 hours 
  • Image result for solar urticaria
Cholinergic Urticaria
  • Irritating, small urticaria spots develop after exercise, hot baths, emotions
  • Occurs after stimuli that evoke sweating from the post-ganglionic cholinergically enervated sweat glands.
  • Cholinergic urticaria develops due to acetyl choline liberated from post ganglionic cholinergic enervated sweat glands under the influence of any stimuli which induces sweating by increasing core body temperature
  • Precipitating factors are exercise/physical exertion, emotion upset, exposure to sun/heat and hot bath/food
  • Characteristic feature is small size pruritic wheals surrounded by large erythema
  • Image result for Cholinergic Urticaria
DRUG-INDUCED URTICARIA
  1. Drug involved:
  2. Penicillin
  3. NSAIDs
  4. Sulphonamides
  5. Aspirin
  6. Fixed drug Eruption
  • Inflamatory patches appear within hours at the same sites on every occasion the drug is administered
  • Leave pigmentation
  • Common drugs are dapsone, tetracycline, sulfonamides, mefenimic acid.
Urticaria Pigmentosa (UP)/Mastocytosis:
  • Mastocytosis is mast cell hyperplasia in 1 organs:
  1. Bone marrow
  2. Liver
  3. Spleen
  4. Lymph nodes, 
  5. Gastrointestinal tract 
  6. Skin. 
  • So mast cell activation may produce symptoms like
  1. Pruritis,
  2. Flushing,
  3. Urtication
  4. Abdominal pain
  5. Nausea, vomiting
  6. Diarrhea
  7. Musculo skeletal pain
  8. Vascular instability
  9. Headache 
  10. Neuropsychiatric difficulties.
  • UP (a type of cutaneous mastocytosis) is the most common manifestation of mastocytosis, both in adults & children.
  • Numerous pale yellow tan to reddish brown monomorphic macules or slightly raised papules develop in a symmetrical distributions anywhere on the body with generally less involvement of the sun exposed areas, with the highest concentration usually being on the trunk and thighs
  • Also generally spared (or less involved) are face, scalp, head, palms & soles. 
  • The edges of lesion are not completely sharp. 
  • It is not uncommon for lesion to become pigmented, hence name urticaria pigmentosa.
  • Development of urticaria, erythema & itching around the lesion after mild trauma, including scratching or rubbing of lesion is called Darier Sign. 
  • Climatic temperature, skin friction, ingestion of hot beverages, spicy foods, alcohol, opioids or other drugs may cause histamine release from mast cells and exacerbate 
  • mastocytosis
  • 3 types/ forms of UP are
  • Juvenile type develop mostly in P, year of life and usually remits spontaneously during adolescence
  1. Adult papular type persists.
  2. Adult telangiectasia macularis eruptive perstans of Parker & Weber: in which telangiectatic macules start to appear, persist and increase in number over the years.
  3. Image result for Urticaria Pigmentosa
Urticarial Vasculitis
  • An important characteristic of urticaria is its transience but rarerly it may stay for days rather than hours & leave a brownish stain
  • It is due to involvement of small vessels
  • Vasculitis urticari typically persist longer than 72 hours, where as conventional urticaria often has a duration of less than 24 -48 hours.
Exam Question
  • Solar urticaria Lesions subsides spontaneously on avoiding exposure within 24 hours 
  • In Solar urticaria Some cases may develop severe urticaria/bronchospasm.
  • Almost all cases of Solar urticaria are idiopathic
  • A 5 year old male child has multiple hyper pigmented macules over the trunk, on rubbing the lesion with the rounded end of a pen. He developed urticarial wheal, confined to the border of the lesion. The most likely diagnosis is Urticaria pigmentosa 
  • Urticaria pigmentosa is a disorder of mast cells
  • Solar urticaria is characterized by Wheal formation
  • Urticaria pigmentosa produce a positive Darier's sign
  • Recurring urticaria are SLE associated rashes
  • Recurrent episodes of flexural exzema contact urticaria is seen in Atopic dermatitis
  • A patient gets reccurent urticaria while doing exercise and on exposure to sunlight suggest Cholinergic Utricaria
  • Investigation done for the diagnosis of itchy tense blisters on normal looking skin and urticarial rash is Direct immunofluorescence
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