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Autumn 2016, Vol. 24 No. 3

Hong Kong J. Dermatol. Venereol. (2016) 24, 167


Answers to Dermato-venereological Quiz

Answers to Dermato-venereological Quiz

CMT Cheung 張敏彤, MM Chang 張苗, PCL Choi 蔡祥龍

  1. Clinical differential diagnoses include acquired perforating dermatosis, excoriated prurigo nodularis, exaggerated arthropod bite reaction, eschars, atypical mycobacterial infection, deep fungal infection, and vasculitis.
  2. Histopathological examination of the skin biopsy showed an inflamed plug with transepidermal/dermal elimination of collagen fibres and surrounding neutrophilic infiltrates.
  3. The diagnosis is acquired reactive perforating collagenosis. Perforating disorders are a group of disorders characterised by transepidermal elimination of components of the dermis, in particular collagen/elastic fibres. They can be inherited, though most commonly observed perforating disorder is acquired reactive perforating collagenosis. Acquired reactive perforating collagenosis affects primarily adults, especially those with diabetes mellitus and chronic kidney disease. They usually present with erythematous or hyperpigmented papules and papulonodules with a central keratotic core that favours the extensor surfaces of extremities.
  4. Treatment can be difficult and is mainly symptomatic. Pruritus can be managed by topical or intralesional steroid, topical anaesthetics, sedating antihistamines or cryotherapy. Topical retinoids have been shown to be effective in some patients. For patients not responding to local therapy, phototherapy (UVB or NBUVB) may dramatically improve pruritus and the number of skin lesions. Case series and case reports have also documented improvement of refractory perforating disorders with allopurinol, oral retinoids and doxycycline.