Pigmented purpuric dermatosis (PPD) is the term used to describe a collection of numerous subtypes of generally benign, chronic, purpuric skin eruptions. Clinically, they are characterized by red to purple macules and patches as well as petechiae with erythrocyte extravasation and hemosiderin deposition in the skin, which can lead to a red-brown to golden-brown color as the hemosiderin is resorbed. They most commonly occur on the lower extremities but can sometimes occur on the arms as well. PPD is often asymptomatic but can be associated with mild pruritus. Treatment can be challenging, but patient reassurance on the benign nature of these diseases is crucial.
Most cases of pigmented purpuric dermatosis are idiopathic. It is important to recognize that these disorders are not associated with coagulopathies or thrombocytopenia. However, since most cases present on the lower extremities, important underlying factors include venous stasis, exercise, and capillary fragility which lead to erythrocyte extravasation into the dermis and the characteristic purpuric color., Due to inflammatory infiltrate of lymphocytes, macrophages, and Langerhans cells which is often seen on skin biopsies as a capillaritis, cell-mediated immunity is also implicated in the pathogenesis of these disorders and may contribute to vascular fragility. Immunohistochemical studies of Schamberg disease, a subtype of PPD, have revealed a perivascular infiltrate of dendritic cells and lymphocytes which interact with vascular endothelial cells and affect the permeability of the microvasculature., Humoral immunity also may be involved in the pathogenesis as immunoglobulin and complement deposition around dermal vessels has been observed in some cases. Many medications also have been reported as causing PPD including acetaminophen, aspirin, carbamazepine, chlordiazepoxide, diltiazem, dipyridamole, furosemide, glipizide, hydralazine, infliximab, interferon-alpha, medroxyprogesterone acetate, meprobamate, pseudoephedrine, raloxifene, and thiamine.,,,,,,
In pigmented purpuric dermatoses, capillaritis in the dermis with possible concomitant venous hypertension leads to endothelial cell dysfunction and extravasation of red blood cells. These erythrocytes deposit in the dermis, clinically manifesting as purpuric macules and patches with variable configurations. Over time, as the hemosiderin is resorbed, golden-brown pigmentation collects in the skin, which over time resolves. However, the disease can often flare and persist chronically.
Skin biopsies show perivascular lymphohistiocytic inflammation around small cutaneous blood vessels with endothelial cell swelling. Leukocytoclastic vasculitis is not observed., Extravasated erythrocytes are often seen in the dermis with variable hemosiderin deposition in macrophages. The hemosiderin tends to occur in the superficial papillary dermis, in contrast to stasis dermatitis, in which the deposition occurs around deeper blood vessels. Mild dermatitis can be seen in the overlying epidermis, manifesting as mild spongiosis with lymphocyte exocytosis. Dermatitis is most pronounced in the PPD variants pigmented purpuric lichenoid dermatitis of Gougerot and Blum and the eczematoid-like purpura of Doucas and Kapetanakis. In contrast, in the lichen aureus variant of pigmented purpuric dermatosis, there is a band of lichenoid lymphocytic inflammation at the dermal-epidermal junction, with a Grenz zone of uninvolved papillary dermis. A rare variant of PPD has also been reported in which granulomatous inflammation was characteristic.
There are many different subtypes of pigmented purpuric dermatosis. Their clinical presentation can mainly distinguish these, but some have unique histopathology as well.
Progressive Pigmentary Dermatosis (Schamberg Disease)
This condition presents as an eruption on the legs that consists of red-brown macules and patches with pinpoint red puncta. These stippled puncta have been likened to grains of cayenne pepper as the skin lesions can often have orange-brown color due to hemosiderin deposition. Although initially described in adolescents, it can affect all ages and on average presents in the fifth decade of life. The condition is most often asymptomatic although mild pruritus can occur. The eruption is most common on the lower legs but can occur on the trunk or arms. A chronic relapsing and remitting course can happen over time.
Purpura Aannularis Telangiectodes of Majocchi
This PPD variant presents with annular patches of punctate red-brown macules and patches on the legs with punctate petechiae at the border. The annular (ring-like) configuration of the patches with central clearing is unique, and annular plaques also can manifest. This eruption typically begins on the lower legs but can spread proximally and may also occur on the arms and trunk. This subtype is most common in females.
The hallmark of lichen aureus is the presentation of ovoid golden orange to mildly purpuric macules, patches and plaques. They may be quite pruritic although are often asymptomatic. The lesions are often unilateral and localized to the legs but can involve the trunk and arms. It is most common in young adults and can have a chronic course which may persist for years. This eruption is also distinguished by a dense band of lichenoid dermal inflammation, in contrast to the other subtypes of PPD, which do not exhibit lichenoid histopathology.
Pigmented Purpuric Lichenoid Dermatitis of Gougerot and Blum
This eruption is distinguished by red-brown to purpuric ovoid papules and plaques that occur on the lower extremities. Although it is named as lichenoid dermatitis, it does not typically exhibit lichenoid histology. Clinically, this condition can mimic Kaposi sarcoma, and therefore, skin biopsies are helpful to make an accurate diagnosis. This subtype is more common in males and can be pruritic.
Eczematoid-Like Purpura of Doucas and Kapetanakis
This condition is characterized by mild scale overlying purpuric and petechial macules, papules and patches. It is often pruritic and the lesions can be extensive and may involve the trunk and arms in addition to the lower extremities. It typically self-resolves over many months.
Disseminated Pruriginous Angiodermatitis (Itching Purpura)
Itching purpura presents acutely on the legs with diffuse purpuric, orange to brown macules and patches, accompanied by severe pruritus. It can evolve to become widespread and often has a chronic course. It is most common in middle-aged men.,
Unilateral Linear Capillaritis (Linear Pigmented Purpura)
This eruption presents as a linear distribution of purpuric to red-brown macules that are unilateral on a lower extremity. It commonly self-resolves. Unilateral linear capillaritis has been reported as a segmental variant of Schamberg disease or lichen aureus.,
Granulomatous Pigmented Purpura
This subtype of PPD has been most often reported in patients of Asian descent. It occurs as red-brown macules, papules, and plaques on the feet and ankles but can occur on the hands and wrists. It is distinguished by dense granulomatous inflammation in the dermis with thickened capillaries and hemosiderin deposition.,,,
Pigmented purpuric dermatoses are largely diagnosed based on the clinical presentation. However, with atypical presentations or to rule out cutaneous vasculitis, dermatitis, or cutaneous t-cell lymphoma, skin biopsy by punch technique can be helpful. CBC and coagulation studies can be performed to rule out thrombocytopenia or clotting disorders. A medication history should also be obtained to screen for drug hypersensitivity as a cause. In order to rule out concomitant allergic contact dermatitis, patch testing can be performed.
It can be challenging to treat pigmented purpuric dermatoses. If a medication reaction is causative, the eruption should clear with discontinuation of the drug. Due to the possible etiology of vascular hypertension and venous stasis of the lower extremities, compression stockings are recommended. A study of 3 patients with PPD revealed clearance of this eruption after 4 weeks of treatment with the bioflavonoid, rutoside 50 mg 2 times per day, and ascorbic acid 500 mg 2 times per day. Given the safety of these supplements, this is a reasonable first-line treatment. Medium to high potency topical corticosteroids such as triamcinolone can also be used and may improve pruritus and the inflammatory component of this condition. Although systemic immunosuppression with corticosteroids or cyclosporine can be helpful, the side effect profile of these medications and the benign nature of PPD may not warrant their use. However, the condition often recurs when immunosuppression is discontinued. Topical tacrolimus or pimecrolimus can be helpful for chronic use to limit the risk of cutaneous atrophy from topical corticosteroids. Griseofulvin 500 mg to 750 mg daily improved 6 patients with PPD. Other case reports of patients with PPD showed improvement with colchicine 0.5 mg 2 times per day, minocycline, methotrexate, and pentoxifylline 400 mg 3 times per day.,, Ultraviolet (UV) light therapy with PUVA or narrowband UVB also has been reported to be beneficial.,,, In some cases, the disease flared with discontinuation of treatment, but in others, sustained remission was achieved., Topical photodynamic therapy using 5-aminolevulinic acid or methyl aminolevulinic acid as photosensitizing agents also has been reported to improve PPD.
The differential diagnosis of PPD includes nummular dermatitis, allergic contact dermatitis, stasis dermatitis, cutaneous vasculitis, Kaposi sarcoma, and cutaneous t-cell lymphoma (CTCL). Cutaneous vasculitis can often be distinguished clinically as palpable purpura with variable cutaneous necrosis, whereas most PPD lesions are not palpable and tend to present most commonly as purpuric macules and patches, although papules and plaques may occur. The clinical history often is helpful as most lesions of PPD are not pruritic, in contrast to dermatitis which is typically pruritic. The presence of lower extremity edema favors venous stasis changes.
Early stages of CTCL (mycosis fungoides) may resemble PPD clinically. There also have been reports of patients initially presenting with PPD who later declare as CTCL. Numerous cases of CTCL have been reported in which patients initially present with the appearance of PPD.,,,,, It, therefore, is critical to follow patients with PPD and perform skin biopsies periodically with lack of improvement or progression of the disease.
PPD is often chronic with a relapsing and remitting course. However, it is a benign, often asymptomatic condition. Even if the capillaritis improves and the active inflammation ceases, the resulting hemosiderin deposition in the dermis can take months to years to slowly fade.
Patients should be reassured that pigmented purpuric dermatoses are benign. Treatment should focus on the relief of symptoms of itching. No treatment is required, however, and observation of the condition is a reasonable approach.