title: A case of suboccipital lump with a rare and unexpected diagnosis of apocrine cystadenoma.
abstract: BACKGROUND
  Cystadenoma of apocrine origin is a tumour of the sweat gland that is benign in nature. Classification of this pathology is based upon histological characteristics plus histochemical analysis. Prevalence of cystadenoma has been suggested to be quite rare, in the region of 1 in 1000 of subcutaneous biopsies observed.
  
  
  METHODS
  We present a case of a 40 year old man referred by his GP with a suboccipital lump, present for some years. On examination the lump was approximately 4-5cm in diameter and an unusual punctum was present. The patient proceeded to an excision of the lesion and the gross specimen showed characteristics of a multiloculated cyst, measuring some 5cm×3.5cm. Histopathology of the tumour revealed an apocrine cystadenoma; there were no features suggestive of malignancy.
  
  
  CONCLUSIONS
  Previous classification of cystadenoma via histological and immunohistochemical method; has revealed only two distinct entities and the term hydrocystoma was often used in place of cystadenoma. More recent studies have suggested that a third type can be identified via immunohistochemical analysis. This third type; apocrine hydrocystoma, reveals that those previously defined as eccrine in origin may also be related to the apocrine ducts.
  
  
  CONCLUSIONS
  Apocrine cystadenoma remains a benign pathology and treatment should be focussed on excision, without need for further intervention. Apocrine cystadenoma remains a relatively rare pathology, though one which should not recur if adequate treatment is given.
authors.affiliation: Gold Coast University Hospital, Australia.
authors.forename: Richard
authors.initials: R
authors.lastname: Maguire
authors.affiliation: Gold Coast University Hospital, Australia; Griffith University, Australia. Electronic address: richard.maguire@my.jcu.edu.au.
authors.forename: Errol
authors.initials: E
authors.lastname: Maguire
keywords: Apocrine; Benign; Cystadenoma; Excision; Lump