Capillaritis also known as pigmented purpura is a benign skin disease characterized by reddish-brown patches that are caused by leaky capillaries. While it can afflict anyone, children are rarely affected by capillaritis. It usually affects healthy individuals, but multiple factors including medications, foods, viral infections, and exercise could trigger it.

Causes:

Capillaritis is thought to be idiopathically caused by a mechanism that irritates the capillaries which are near the skin’s surface. The pathophysiology behind this disease is due to the passage of blood cells through the gaps between the capillary walls resulting in petechial hemorrhage which fades away depositing haemosiderin in the the dermis’ uppermost part.

Clinical features:

Red-brown purpuric macules “cayenne pepper spots” are the characteristic features of capillaritis. These may be distributed over the body or cluster together forming a red patch that gradually disappears over weeks to months.

Types and variants:

Progressive pigmented purpura (schamberg disease): The most common type of capillaritis, presented by cayenne pepper spots which appear suddenly. Most commonly on the lower leg, with irregular distribution and no associated symptoms.

Doucas-Kapetanakis eczematid-like purpura (itching purpura): Similar to schamberg disease bit with itching. It can affect the trunk and upper limbs.

Gougerot-Blum purpura (pigmented purpuric lichenoid dermatosis): Characterized by thick and itchy patches similar to eczema.

Majocchi purpura (purpura annularis telangiectodes): Characterized by annular patches that spread gradually and form concentric rings.

Lichen aureus: Overlies varicose vein and is characterized by a persistent single brown patch.

Exercise-induced capillaritis: common in prolonged exercise during the summer. The lesions fade with time. The appearance of the lesions is associated with a burning sensation.

Diagnosis:

The diagnosis is made clinically. It can be confirmed by skin biopsy and dermatoscopy. Histology may reveal red cell extravasation, hemosiderin, perivascular lymphocytic infiltrate, and lichenoid infiltrate, these findings could be found in one or more variants. In immunocompromised patients always rule out cutaneous T-cell lymphoma.

Management:

Usually, no treatment is required, and unfortunately, no cure is known. However, avoiding possible risk factors including medications, food preservatives, and artificial coloring agents could result in improvements. Topical steroids can be used for symptomatic treatment. Ascorbic acid and rutoside can be used also. Phototherapy may be effective but with recurrence risk. Elastic compression socks can be used in exercise-induced capillaritis. Ascorbic acid and rutoside can be used also.

Outcome:

Capillaritis can go away in a few weeks, come back occasionally, or last for years.

Written by:

Mohammed Alahmadi, Medical Student.

Revised by:

Maee barakeh, Medical student.
References:

DermNet

Andrews’ Diseases of The Skin, Clinical Dermatology

Dermatology, Illustrated Study Guide and Comprehensive Board Review by Sima Jain

British Association of Dermatologists