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Winter 2015, Vol. 23 No. 4

Hong Kong J. Dermatol. Venereol. (2015) 23, 219


Dermato-venereological Quiz

Answers to Dermato-venereological Quiz

KK Jong 莊國坤and ECY Chu 朱灼欣

  1. The differential diagnosis includes post-inflammatory hyperpigmentation, erythema dyschromicum perstans, lichen planus pigmentosus, lichen planus-like drug eruption.
  2. It showed a piece of skin featuring an atrophic epidermis. Prominent melanophages are found in the upper dermis. Focal lymphocyte exocytosis at the basal layer of the epidermis is present. The upper dermis shows mild perivascular lymphocytic infiltration with many macrophages.
  3. The diagnosis is erythema dyschromicum perstans (ashy dermatosis). Erythema dyschromicum perstans is an asymptomatic eruption of oval, polycyclic grey-blue hyperpigmented macules on the trunk, limbs or face. The patches which are of variable size and shape begin as ash-coloured macules, sometimes with an erythematous or elevated border which represents the active lesions. The aetiology of erythema dyschromicum perstans (ashy dermatosis) remains unknown, but many regard it as a form of lichen planus or lichen planus actinicus. Some suggested the association with ingestion of ammonium nitrate, whipworm infection and orally administrated radiographic contrast media, but a definite aetiology has not been established.
  4. Many therapeutic modalities have been attempted, but none with satisfactory results. The use of narrow-band UVB phototherapy has shown to be effective in a few patients. A low-potency topical steroid may be used on the affected areas. There has been a case report of good response to dapsone. There has also been a case series of good or excellent response to clofazimine.
  5. Erythema dyschromicum perstans has no systemic symptoms or associations. It runs a benign course with complaints relating to cosmetic issues.