title: Misleading initial histological diagnosis of a polymorphous low-grade adenocarcinoma in situ ex pleomorphic adenoma-a case report.
abstract: BACKGROUND
  Polymorphous low-grade adenocarcinoma (PLGA) are frequent tumours of palatinal minor salivary glands. They appear clinically as solid mass located beneath intact surface epithelium, thus quite similar with benign neoplasm. PLGA displays a low tendency of aggressive behaviour. The correct aetiology of this disorder is still unknown.
  
  
  METHODS
  In this contribution, a PLGA is reported which was located in a pleomorphic adenoma (PA). Out of an initially incisional biopsy, only the benign part of the lesion was diagnosed. Definitive histological examination of the whole tumour revealed a small malignant fraction of the specimen besides a major part of benign tissue formations (PA).
  
  
  CONCLUSIONS
  This case shows the uncertain confidence of incisional biopsy, the variably biologic behaviour of PA, providing hints for consideration of the PLGA aetiology and highlights both the necessity to remove whole PA-like lesions as well as to perform systematically histological examination of whole specimens.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Johannes Gutenberg-University, Augustusplatz 2, 55131, Mainz, Germany. kaemmerer@mkg.klinik.uni-mainz.de
authors.forename: P W
authors.initials: PW
authors.lastname: Kämmerer
authors.forename: A
authors.initials: A
authors.lastname: Kreft
authors.forename: T
authors.initials: T
authors.lastname: Toyoshima
authors.forename: B
authors.initials: B
authors.lastname: Al-Nawas
authors.forename: M O
authors.initials: MO
authors.lastname: Klein
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology*; D008949:Adenoma, Pleomorphic / Q000473:pathology*; D000368:Aged; D001706:Biopsy / Q000379:methods; D002278:Carcinoma in Situ / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D009378:Neoplasms, Multiple Primary / Q000473:pathology*; D010157:Palatal Neoplasms / Q000473:pathology*; D012468:Salivary Gland Neoplasms / Q000473:pathology; D012470:Salivary Glands, Minor / Q000473:pathology