Description

The pigmented purpuric dermatoses are a group of chronic skin diseases with a characteristic appearance. The aetiology is unknown but they tend to affect the lower limb¹ and there is extravasation of erythrocytes in the skin with marked deposition of haemosiderin.

There are a number of clinical patterns but all with a similar histological appearance. Generally, the treatment and prognosis is similar. The pigmented purpuric dermatoses² include:

• Schamberg's disease (progressive pigmentary dermatosis)
• Majocchi's disease (purpura annularis telangiectodes)
• Lichen aureus
• Itching purpura
• Eczematid-like purpura of Doucas and Kapetanakis
• Pigmented purpuric lichenoid dermatosis of Gougerot and Blum

Many consider itching purpura and eczematid-like purpura to be variants of Schamberg's disease.

Pathophysiology

The aetiology is unknown but important contributory factors include venous hypertension, exercise, and gravitational dependency. Histology shows a perivascular lymphocytic infiltrate of T-cells centred on the superficial small blood vessels of the skin, suggesting that cell-mediated immunity plays a part.³ There is swelling of endothelial cells and narrowing of the lumen. Extravasation of red blood cells occurs with marked deposition of haemosiderin in macrophages, and a rare granulomatous variant of chronic pigmented dermatosis has been reported.

Epidemiology

The conditions are uncommon. Generally they affect males more than females, except in Majocchi's disease. There is no racial difference in incidence.

• Schamberg's disease occurs at any age.
• Itching purpura and the dermatosis of Gougerot and Blum typically affect middle-aged men.
• Lichen aureus and Majocchi's disease occur mostly in children or young adults.

Both Schamberg's disease and Majocchi's disease have rarely been reported in families, suggesting a genetic aetiology or predisposition. It may be autosomal dominant.⁴

Risk factors

Some forms of the pigmented purpuric dermatoses are associated with the ingestion of drugs, including aspirin and thiamine.⁵ Lichen aureus may be associated with trauma.

Associated diseases

Schamberg's disease

• Schamberg's disease is the commonest form of pigmented purpura, and is the most common cause of petechiae in children. It is most commonly seen in the late teens and early 20s, although has been diagnosed in children between 1 and 9 years old.⁶ It is more common in males than females, although a report of children included 3 boys and 10 girls.⁶
• The lesions were initially described by Schamberg as having the appearance of "Cayenne pepper spots" due to the reddish pinpoint lesions which border larger discrete reddish brown patches. The lesions, which are usually asymptomatic, occur most often on the anterior surface of the lower limb bilaterally but may also involve the upper limbs, buttocks and trunk.
• Schamberg disease is a chronic relapsing skin disorder, which does not appear to be associated with any concurrent illness but has been seen in association with certain therapies including aspirin, thiamine and carbamols.
• It is a benign disorder which does not result in any physical abnormality. Treatment with oral corticosteroids may clear the skin lesions but systemic side effects tend to outweigh benefit. Topical corticosteroids are not effective.
• Rarely, Schamberg's disease has been diagnosed in children who went on to develop cutaneous T-cell lymphoma.

Majocci's disease (purpura annularis telangiectoides)

• Majocci's disease, typically presents with annular erythematous plaques and patches which have central areas of atrophy, commonly in a symmetrical distribution on the lower limbs but occasionally on the trunk and upper limbs.
• Girls are more often affected than boys, most often in adolescence or early adulthood.
• Despite a chronic relapsing course which lasts several years, the disorder is benign and self-limiting and treatment is neither effective nor required.

Pigmented purpuric lichenoid dermatosis of Gougerot and Blum

• This condition is extremely similar to Majocci's disease but presents in adults, usually men, and is not seen in children.
• Unlike Majocci's disease, the pigmented lichenoid papules and plaques respond well to treatment with PUVA.

Eczematoid-like purpura of Doucas and Kapetanakis

• This disorder is similar to Schamberg's disease but occurs predominantly in adult males.
• The lesions, which may be itchy, commonly begin on the lower legs and progress to the thighs, trunk and upper limbs.
• It is a chronic relapsing disorder which may remit spontaneously.
• Lichenification may also be present due to chronic scratching of the pruritic lesions.

Lichen aureus

• Lichen aureus, as its name suggests, presents with yellowish or red papules or patches which may either itch or be asymptomatic.
• The lesions frequently occur bilaterally on the lower limbs, although can be unilateral and may affect the trunk and upper limbs.⁷
• Unlike the other forms of pigmented purpuric eruptions, the lesions of lichen aureus may also occur in a dermatomal distribution, or can follow the distribution of veins or arteries.
• It is thought that it may sometimes be associated with trauma but it does not appear to be associated with the ingestion of drugs.
• Once again, although the lesions may be cleared using oral corticosteroids, the risks of treatment outweigh the benefits, as it follows a benign course.
• Dramatic improvement with PUVA has been reported.⁸

Differential diagnosis

Despite the distinctive appearance of the lesions, several other conditions must be considered as a differential diagnosis including:

• T-cell lymphoma
• Self-induced haematomas
• Scurvy
• Benign hypergammaglobulinaemic purpura of Waldenström
• Drug eruptions
• Henoch-Schönlein purpura
• Kawasaki's disease
• Thrombocytopenia

Investigations

• There is no specific investigation to diagnose the disorder.
• Routine laboratory investigations such as FBC, clotting studies and ESR show no abnormality although they may be performed to exclude other disease.
• There are no established guidelines for investigation of patients with pigmented purpuric lesions. Where skin biopsies are performed, histology will reveal evidence of capillaritis of the upper dermal vessels, extravasation of the red blood cells with haemosiderin deposits in the macrophages and an essentially normal epidermis. Biopsy may be helpful to exclude an early T-cell lymphoma.

Management

Non-drug

• Avoid prolonged dependency of the legs.
• If there is venous stasis, compression may be beneficial.
• In view of the appearance and the chronic nature of the disorder, both children and their parents will require reassurance as to the benign nature of the disorder.
• Adolescents and young adults may benefit from counselling because of the unsightly nature of the lesions.
• Schamberg's disease and pigmented purpuric lichenoid dermatosis of Gougerot and Blum may benefit from treatment with PUVA. ^9,10
• Difficult or persistent cases of pigmented purpuric eruption may benefit from narrowband UVB therapy.¹¹

Drugs

• The pigmented purpuric dermatoses follow a benign but chronic course. Although treatment with oral steroids can be effective in clearing the lesions, these are not generally used as the risks of treatment far outweigh any potential benefits.
• Antihistamines may offer relief from pruritus but at the cost of sedation.
• Topical steroid creams may bring some symptomatic relief.
• Aminaphtone has been found to be helpful in Schamberg's disease (not licensed in the UK).

Prognosis

• All forms of pigmented purpuric dermatoses have a chronic, relapsing and remitting benign course and are not associated with any other physical abnormality.
• Spontaneous remissions may occur.
• Very rare descriptions have occurred of T-cell lymphoma occurring in patients with a diagnosis of Schamberg's disease.¹²