Chronic pigmented purpuras are several diseases of capillaritis characterized by petechial hemorrhage, though without any sys-temic involvement. This group of pig-mented purpuras is diagnosed clin-i-cally, and patients can be reassured that the lesions are benign. Although treatment is similar for the different variants, it can be challenging.

Purpura refers to the visible extravasation of blood into the skin or mucous membranes. Lesions of non-pal-pable purpura can be named according to their diameter (see Table 1).

Chronic pigmented purpura affects superficial vessels of the dermis. The underlying etiology is mostly idiopathic, with hypotheses suggesting two underlying components: stasis and a T-cell-mediated reaction. This condition has been linked to venous stasis, dependent extremities and exercise. Patients with pigmented purpura rarely report a family history.

Some forms of pigmented purpuric eruptions are relatively rare and af-fect men more often than women. They include pigmented purpuric dermatosis of Gougerot and Blum, Majocchi's disease, lichen aureus and Schamberg's disease (progressive pig-mentary dermatosis) (see Table 2).

A clinical picture of capillaritis
Pigmented purpuric dermatosis of Gougerot and Blum typically affects patients in their fifth and sixth decades. This form of capillaritis is identified by pigmented purpura with lichenoid papules. Lesions are characteristically chronic and asymptomatic.

Majocchi's disease predominantly targets adolescents and young adults, and unlike the other forms, is more com-mon in women. Lesions generally look like 1-3 cm annular plaques of purpura with telangiectasias and a smattering of red dots around the rim, referred to as cayenne pepper spots. They're persistent and gradually become larger.

Lichen aureus tends to be a localized, persistent purpuric capillaritis. Although it can occur in children, this form most commonly affects young adult men. Clinically, lesions are isolated or aggregated; they look like rust- or purple-coloured macules and papules with some petechiae. The patches are often noted on the lower legs, but may involve other sites of the body. Lichen aureus may some-times occur in a zosteriform dis-tri-bution pattern.

Schamberg's disease is the most common of the pigmented purpuras, affecting individuals of all ages, though the typical patient is an older man with involvement of the lower legs. Lesions are often elliptoid, irregular, orange-to-brown patches with a characteristic sprinkling of cayenne pepper-like spots, both with-in and at the edges of older lesions. There's of-ten a symmetrical distribution limited to the lower legs.

Patients will often complain about the appearance of the lesions, and occasionally, they may also suffer from pruritus. With all forms of this disease, petechiae can be confirmed by pressing a glass slide over the lesions; if the lesions persist with pressure, a diagnosis of some form of purpura can be made.

With time, lesions will frequently become more pigmented as a result of post-inflammatory and hemo-siderin-induced hyperpigmentation. Schamberg's disease can last several months and can be chronic and relapsing if a possible underlying cause isn't treated.

Schamberg's disease and the other chronic pigmented purpuras are clinical diagnoses. Systemic features, a preceding rash or stasis dermatitis, aren't common. Similar appearances can be caused by a food additive sensitivity, contact allergy to clothing and hyperglobulinemia. Certain drugs have also been known to cause hypersensitivity reactions that appear similar to the chronic pigmented purpuras (i.e. furosemide, carbamazepine, rituximab).

To rule out other causes of purpura, investigations may include a platelet count, prothrombin time, and activated partial thromboplastin time. If in doubt, a biopsy will confirm the diagnosis and rule out early cutaneous T-cell lymphoma (mycosis fungoides), small vessel vasculitis, and angioma serpiginosum. For persistent cases, it's especially important to rule out cutaneous lymphoma.

Time is therapeutic
Although the purpuras are benign conditions, psychosocial reasons may prompt patients to request treatment. Their appearance and uncertainty can be quite distressing for some individuals. Consequently, reassurance is very important. Given the lack of a proven modality, treatment is variable. Fortunately, chronic pigmented purpuras are often self-limited.

Compression stockings are helpful for patients with lesions on the lower legs and known venous stasis, in addition to avoiding dependent positions.

If lesions are symptomatic (i.e. pruritus, erythema), consider using topical corticosteroids, with or without antihistamines. Topical steroids may accelerate healing to within several weeks, or they may simply prevent lesions from spreading.

Topical immunomodulators (i.e. pimecrolimus) may also be beneficial. This agent is a better treatment option to topical steroids because it doesn't cause skin atrophy. Apply pimecrolimus 1% cream to lesions twice a day; improvement may be noted by three weeks, while lesions can be cleared by 10 weeks.

Pentoxifylline is thought to hinder T-cell adherence to endothelial cells and keratinocytes and has been shown to be effective in Schamberg's disease. A recent randomized controlled trial showed that pentoxifylline 400 mg p.o., t.i.d. was superior to topical betamethasone dipropionate cream 0.05% applied to lesions twice daily.

Phototherapy with PUVA and narrow band UVB (twice weekly treat-ments for 12 weeks) are other options for persistent lesions. Phototherapy suppresses the immune response in the skin. Its success in treating Schamberg's disease has been attributed to the suppression of T-cells found in the skin in early stages of the disease.