title: Acquired trichostasis in postoperative site: a case report.
abstract: BACKGROUND
  Usual causes of a papule or nodule in a post-operative site after resection of a skin tumor are residual or recurrent tumor, proliferative scar, or suture granuloma with inflammation and granulation tissue. Inverted or trapped hair, an acquired trichostasis, has not been implicated as a cause in such cases, this is probably the first case reported in literature.
  
  
  METHODS
  A 31-year-old woman underwent an excision of a ruptured epidermal cyst of the left axilla. One month later, the previous excision site was re-excised secondary to a non-healing, inflamed papule in order to exclude recurrent epidermal cyst formation. Microscopic examination revealed that the cause of the papular lesion was acquired trichostasis, rather than a recurrent epidermal cyst.
  
  
  CONCLUSIONS
  A papular or nodular lesion at a postoperative site may rarely be caused by acquired trichostasis and should be considered as one of the differential diagnosis.
authors.affiliation: Department of Pathology, Creighton University Medical Center, Omaha, NE, 68131, USA.
authors.forename: Deba P
authors.initials: DP
authors.lastname: Sarma
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Maertins
authors.forename: Eric E
authors.initials: EE
authors.lastname: Santos