Pigmented purpuric dermatoses: causes, symptoms, diagnosis, and treatment

Pigmented purpuric dermatoses, also known as pigmentary purpuric eruptions, or capillaritis, are a group of purpuric dermatoses with analogous clinical morphology and histopathology, mostly chronic, and 2/3 of patients can gradually improve, eventually in remission.


Causes

The cause is unknown. The gravity and elevation of venous pressure are important local predisposing factors. Exercises may be a motivating factor. It is thought that purpura annularis telangiectodes may be a manifestation of certain systemic diseases such as cardiovascular and renal diseases, but most patients with this disease are healthy. Perivascular infiltrating lymphocytes CD4+ and CD1a+ Langerhans cells suggest a cell-mediated immune response, and there is no deposition of immune complexes.

This group of diseases can be occasionally caused by medications or food additives. This disease can also occur on the basis of rheumatoid diseases, or may be a manifestation of mycosis fungoides (MF), sometimes even the only manifestation of MF. Drugs that cause capillaritis include calcium channel antagonists, β-blockers, angiotensin converting enzyme inhibitors, nitrites, furosemide, antihistamines, antidepressants, chlordiazepoxide, analgesics such as acetaminophen, glipizide, vitamin B1 derivatives, lemon, IFN-α (for HCV infection), polyvinylpyrrolidone, and topical FU.


Signs and Symptoms

Progressive pigmented purpuric dermatosis

Progressive pigmented purpuric dermatosis, also known as Schamberg's disease, is more common in young males, but can occur at any age, including childhood. Very few patients have familial morbidity. There are clustered, pinpoint sized, red petechiae initially, developing into dense irregular patches, gradually expanding peripherally. The center turns gradually brown due to the deposition of hemosiderin. New petechiae occur constantly in the old skin lesions or at the edges of old skin lesions. Skin lesions vary in number, ranging from several or dozens, mostly on the calves and ankles, as well as other areas such as the palms. Generally, there are not subjective symptoms, but very few patients may have mild pruritus. The skin lesions slowly spread peripherally. Sometimes, the old skin lesions gradually subside, but new skin lesions occur, lasting for many years, eventually subsiding spontaneously. Many patients may be accompanied by other pigmented purpuric dermatoses.

Pigmented purpuric lichenoid dermatitis

Pigmented purpuric lichenoid dermatitis, also known as Gougerot-Blum syndrome, a variant of pigmented purpuric dermatosis, is manifested by small rusty lichenoid papules, accompanied by purpuric lesions, which can progress into poorly demarcated plaques with different colored papules (purpura with lichenoid dermatitis). The disease occurs mostly on the calves, but also on the thigh and lower trunk, more common in 40 - 60 years old adults, mainly males. The difference between this disease and progressive pigmented purpuric dermatosis is the distribution of skin lesions and occurrence of lichenoid papules. The papules of this disease often cluster into plaques. The disease can be accompanied by porphyria, and similar lesions can occur in the oral mucosa.

Purpura annularis telangiectodes

Purpura annularis telangiectodes, also known as Majocchi's disease, can occur at any age, more common in young adults. Very few patients can have familial morbidity. Purplish red annular macules occur initially, with a diameter of 1 - 3cm, and punctate dark red telangiectasia or petechiae occur in the macules. Skin lesions may be purple, yellow, or brown due to the deposition of hemosiderin. Some skin lesions may have mild atrophy in the center. A single lesion can last for months or years without changes, or the center gradually subsides, and the edges slowly expand peripherally, forming an annular, semi-annular, arciform, or concentric lesion with mild central atrophy. Sometimes the old rash subsides and a new rash occurs in the vicinity. The number of rashes range from several to dozens. Skin lesions occur on the calves initially, spreading up to the thigh, buttocks, torso, and upper limbs. Venous stasis and subjective symptoms are usually absent. Due to the repeated episodes, the disease can persist for several years, with a tendency to self-healing.

Few large irregular arciform lesions, termed purpura annularis telangiectodes (arciform type, Touraine), is a subtype of this disease.

Granulomatous pigmented purpuric dermatosis

Granulomatous pigmented purpuric dermatosis is a rare form of pigmented purpuric dermatosis with granuloma in histopathology.

Familial pigmented purpuric eruption

Familial pigmented purpuric eruption can occur in multiple members of a family, possibly autosomal dominant, and is characterized by scattered reddish brown spots in childhood and adolescence. A single spot is larger than that of progressive pigmented purpuric dermatosis. The spots are arranged in mosaic patterns, and the skin lesions gradually develop, mainly in the limbs and large skin folds. There are no subjective symptoms.

Linear and quadrantic pigmented purpuric dermatoses

Different forms and types of pigmentary purpuric rashes can occur, and may be linear, zonal, or diffuse on the lateral body. A single lesion is often similar to that of lichen aureus or progressive pigmented purpuric dermatosis.


Histopathology

The pathological changes of this group of diseases are basically similar. In the early stage, capillary endothelial cell swelling, narrowed lumen, massive lymphocyte and histocyte infiltration around the capillaries, occasionally a small amount of neutrophils, and estravasation of erythrocytes in the upper dermis and dermal papillae can be seen. The infiltrating cells can be seen in the epidermis, and mild spongiosis and discrete parakeratosis in the prickle cell layer are visible. In the old skin lesions, the inflammatory infiltration is not as obvious as that of early lesions, capillary lumen expansion and endothelial cell proliferation are present, estravasation of erythrocytes is absent, and hemosiderin are visible.


Diagnosis

On the basis of clinical manifestations, the diagnosis is not difficult.


Treatment

This group of diseases can last for several years and has no obvious effect on any treatment. Stretch socks, oral vitamin C or rutin, and topical glucocorticoid preparations can be used, mainly in patients with pruritus. It has also been reported that photochemotherapy (PUVA) is effective in the treatment of progressive pigmented purpuric dermatosis and pigmented purpuric lichenoid dermatitis. Cyclosporine and griseofulvin have also been reported to be effective.