title: Letrozole-induced necrotising leukocytoclastic small vessel vasculitis: First report of a case in the UK.
abstract: BACKGROUND
  Letrozole, an aromatase inhibitor, is a commonly used neo-adjuvant drug to treat hormone-sensitive breast cancer. There have been a few cases of aromatase inhibitor induced vasculitis but the first case of letrozole-induced vasculitis was reported from Switzerland in 2014 (Digklia et al.) [1].
  
  
  METHODS
  We report the case of a 72-year-old woman with a small breast cancer. She was started on pre-operative letrozole (2.5mg/d) whilst awaiting surgery. Ten days later she presented with burning pain and purpuric skin lesions which progressed to extensive ischaemic superficial necrosis of the lower limb skin, resolving over 3-4 months after local and systemic steroids. Histologically, it showed leucocytoclasis with evidence of eosinophilia consistent with a diagnosis of cutaneous leukocytoclastic small vessel vasculitis.
  
  
  CONCLUSIONS
  The initial clinical presentation was severe burning pain around the ankles and a spreading violaceous rash. Letrozole was stopped. Wide local excision (lumpectomy) and sentinel node biopsy were postponed because of the accompanying pneumonitis and gastrointestinal upset, and were carried out 3.5 months later. Fortunately, the tumour size did not increase, but appeared to reduce, and axillary lymph nodes remained negative, i.e., this patient's cancer outcome does not seem to have been jeopardized.
  
  
  CONCLUSIONS
  Leukocytoclastic vasculitis is a hypersensitivity reaction that is usually self-resolving, though our case needed systemic steroid treatment. Letrozole is a commonly used drug in clinical practice and prescribers should be aware of this rare side effect, which in our case delayed treatment without any apparent harm and possibly reduced tumour size.
authors.affiliation: University College London Medical School, Gower St, London WC1E6BT, United Kingdom.
authors.forename: Pirunthan
authors.initials: P
authors.lastname: Pathmarajah
authors.affiliation: University College London Medical School, Gower St, London WC1E6BT, United Kingdom.
authors.forename: Karishma
authors.initials: K
authors.lastname: Shah
authors.affiliation: Department of Dermatology, The Whittington Hospital, London N195NF, United Kingdom.
authors.forename: Kathy
authors.initials: K
authors.lastname: Taghipour
authors.affiliation: Department of Histopathology, The Whittington Hospital, London N195NF, United Kingdom.
authors.forename: Su
authors.initials: S
authors.lastname: Ramachandra
authors.affiliation: The Breast Unit, The Whittington Hospital, London N195NF, United Kingdom; Centre for Cancer Prevention, Wolfson Institute of Preventive Medicine, Queen Mary University of London, EC1M 6BQ, United Kingdom.
authors.forename: Mangesh A
authors.initials: MA
authors.lastname: Thorat
authors.affiliation: The Breast Unit, The Whittington Hospital, London N195NF, United Kingdom.
authors.forename: Ziaullah
authors.initials: Z
authors.lastname: Chaudhry
authors.affiliation: The Breast Unit, The Whittington Hospital, London N195NF, United Kingdom.
authors.forename: Vivek
authors.initials: V
authors.lastname: Patkar
authors.affiliation: The Breast Unit, The Whittington Hospital, London N195NF, United Kingdom.
authors.forename: Francesca
authors.initials: F
authors.lastname: Peters
authors.affiliation: The Breast Unit, The Whittington Hospital, London N195NF, United Kingdom.
authors.forename: Thomas
authors.initials: T
authors.lastname: Connor
authors.affiliation: The Breast Unit, The Whittington Hospital, London N195NF, United Kingdom.
authors.forename: Emma
authors.initials: E
authors.lastname: Spurrell
authors.affiliation: The Breast Unit, The Whittington Hospital, London N195NF, United Kingdom.
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Tobias
authors.affiliation: The Breast Unit, The Whittington Hospital, London N195NF, United Kingdom; Division of Surgery and Interventional Science, University College London, 132 Hampstead Road, London NW1 2PS, United Kingdom. Electronic address: jayant.vaidya@ucl.ac.uk.
authors.forename: Jayant S
authors.initials: JS
authors.lastname: Vaidya
keywords: Breast cancer; Hypersensitivity reaction; Letrozole; Leukocytoclastic vasculitis