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Pigmented purpuric dermatosis: a striking but benign cutaneous entity
  1. Hannah Song1,
  2. Johanna S Song1,2,
  3. Margaret Choy Merola1,3,
  4. Rosalynn M Nazarian1,3,
  5. Elena B Hawryluk1,2
  1. 1Department of Dermatology, Harvard Medical School, Boston, Massachusetts, USA
  2. 2Department of Dermatology, Massachusetts General Hospital, Boston, Massachusetts, USA
  3. 3Department of Pathology, Massachusetts General Hospital, Boston, Massachusetts, USA
  1. Correspondence to Dr Elena B Hawryluk, Department of Dermatology, Massachusetts General Hospital, 50 Staniford Street, Boston, MA 02114, USA; Elena.hawryluk{at}childrens.harvard.edu

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A child presented with a 6-month history of an asymptomatic, progressive rash. The rash started on her right lower calf and spread to her dorsal foot and superior thigh. Physical exam demonstrated brown-to-orange purpuric macules on her right lower extremity (figure 1). Laboratory tests including complete blood count (CBC) and antinuclear antibodies (ANA) were unremarkable. Skin biopsy revealed a superficial lymphocytic infiltrate and extravasated erythrocytes, consistent with pigmented purpuric dermatosis (PPD) (figure 2). Recommended treatment included natural sunlight, rutoside and ascorbic acid, and the eruption slowly improved.

Figure 1

Right leg with petechial macules.

Figure 2

High-power view showing extravasated erythrocytes in the superficial dermis and focal pigment incontinence.

PPD are cutaneous eruptions that present with asymptomatic or pruritic macules and petechiae with red and brown pigmentation. PPD have a predilection for the lower limbs. They are often chronic and relapsing, with median resolution time of <1 year.1 Histology demonstrates a perivascular infiltration with skin-specific T lymphocytes, erythrocyte extravasation and hemosiderin in macrophages.1 Triggers include infections, medications and gravitational dependence.2 Treatment options include topical corticosteroids, phototherapy—psoralen and ultraviolet A or narrow-band ultraviolet B, or rutoside and ascorbic acid.3 Rutoside, an oral bioflavonoid, and ascorbic acid are antioxidants that reduce capillary permeability by scavenging reactive oxygen species, and have been highly effective in case reports and a small retrospective study;2 ,4 however there is limited evidence to support any treatment, given the overall benign, self-limited course of the disease.

Differential diagnoses include thrombocytopenia, small-vessel vasculitis, allergic contact dermatitis, angioma serpiginosum and unilateral nevoid telangiectasia. Identification of clinical features of PPD can prevent extensive workup for vasculitis or malignancy. Treatment for children should focus on low-risk options, given the benign course. However, worsening eruptions, or large intraepidermal lymphocytes on histopathology, may prompt consideration of mycosis fungoides, which can very rarely present with a pigmented purpuric eruption.5

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Footnotes

  • Contributors HS wrote the first draft of the manuscript. JSS and EBH contributed to the critical revision of the manuscript. MCM and RMN obtained photographic documentation.

  • Competing interests None declared.

  • Patient consent Obtained.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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