Contents
Papular urticaria, also called a persistent insect bite reaction is a chronic hypersensitivity reaction from arthropod/insect bites, commonly seen in children.
Etiology
Insect bites:
The differentiation between mosquitoes and fleas bite is suggested by clinical identification of corporal distribution of the bites.
- Flea bite papular urticaria (FBPU) (M/C associated): Fleas and mites that live on cats and dogs are most often responsible
- Mosquito bites
- Bedbug bite: Multiple, painless and linear in configuration
- ‘Breakfast, lunch, dinner’ sign: Row of 3 bedbug bites
Risk factors:
- Children (M/C group): Desensitisation to insect bites has not yet developed
- Adults: Travellers to new environments.
Presentation
Characterized by a hypersensitivity reaction that can be manifested most commonly through papule-type skin lesions, and sometimes through wheals, vesicles, blisters or scabs.
- Most often they arise on legs and other uncovered areas such as forearms and face.
- Sometimes papules are scattered in small groups all over the body [3].
- They appear every few days during the summer or autumn months.
- They range from 0.2–2 cm in diameter.
- Each papule has a central punctum.
- Papular urticaria may present as crops of fluid-filled blisters.
- New lesions develop just as old ones start to clear.
Occasionally, as a result of the constant bites, the patient might develop hypo-or hyperchromic residual pigmentations in the skin with intense pruritus, severe infections and scarring.
- Secondary bacterial infection causes painful pustules and scabs (impetiginisation).
- Sometimes one new spot provokes old ones to come up again and itch intensely.
Diagnosis
Skin biopsy:
Useful both in confirming the diagnosis and in persuading the parents regarding the nature of the condition.
- Spongiosis (epidermal edema)
- Subepidermal edema
- Mixed inflammatory infiltrate often including eosinophils
Differential diagnosis:
- Ordinary urticaria: Despite the name, papular urticaria is not true urticaria, which is characterised by temporary wealing that resolves within hours. Weals in papular urticaria last for days to weeks. Papular urticaria is not associated with an internal complaint.
- Pityriasis lichenoides et varioliformis acuta (PLEVA)
- Gianotti Crosti syndrome: Papular acrodermatitis of childhood
- Lymphomatoid papulosis
Management
Symptomatic treatment:
- Oral antihistamines
- Topical corticosteroids
- Topical antipruritic preparations containing menthol, camphor, or pramoxine.
Environmental control measures:
Desirable to do so when feasible
- Wearing full protective clothing
- Avoiding insect infested areas
- Reducing utilization of public transport
- Insect repellant use