title: Doing more with less: the challenging diagnosis of polymorphous low-grade adenocarcinoma in incisional biopsy samples.
abstract: OBJECTIVE
  The diagnosis of polymorphous low-grade adenocarcinoma (PLGA) remains difficult for general pathologists, particularly in cases of small biopsy samples. We aimed to characterize the histopathological spectrum and immunohistochemical aspects by using an accessible immunohistochemical panel of cytoskeletal proteins in limited samples of PLGA.
  
  
  RESULTS
  Forty-six patients diagnosed with PLGA in incisional biopsies were identified retrospectively. Seventy-two per cent of patients were women and 28% were men, with a mean age of 55 years. The palate was the most affected site. Grossly, the mean size of the samples was 0.8 cm and 74% of specimens were fragmented. All tumours characteristically displayed the microscopic features of architecturally diverse patterns, infiltrative areas and low-grade cytology. Neoplastic cells were diffusely positive to cytokeratin (CK) 7, vimentin and S100 protein, but only focally positive to CK14 and negative to α-smooth muscle actin (α-SMA), thus lacking myoepithelial differentiation.
  
  
  CONCLUSIONS
  Microscopic recognition of PLGA is facilitated by a characteristic combination of multiple architectural patterns of growth, infiltration of adjacent tissues and cytological aspects. These features are present even in small biopsy samples. The association of histopathological aspects with CK7, CK14, vimentin, S100 and α-SMA immunoexpression is helpful in reaching the diagnosis of doubtful cases.
authors.affiliation: Department of Oral and Maxillofacial Pathology, School of Dentistry, University of São Paulo, São Paulo, Brazil.
authors.forename: Bruno T
authors.initials: BT
authors.lastname: Sedassari
authors.affiliation: Department of Oral Diagnosis, Piracicaba School of Dentistry, State University of Campinas, São Paulo, Brazil.
authors.forename: Harim T
authors.initials: HT
authors.lastname: Dos Santos
authors.affiliation: Department of Oral and Maxillofacial Pathology, School of Dentistry, University of São Paulo, São Paulo, Brazil.
authors.forename: Fernanda M
authors.initials: FM
authors.lastname: Pigatti
authors.affiliation: Department of Oral and Maxillofacial Pathology, School of Dentistry, University of São Paulo, São Paulo, Brazil.
authors.forename: Maria C
authors.initials: MC
authors.lastname: Martins Mussi
authors.affiliation: Department of Oral and Maxillofacial Pathology, School of Dentistry, University of São Paulo, São Paulo, Brazil.
authors.forename: Priscila L
authors.initials: PL
authors.lastname: Tobouti
authors.affiliation: Department of Anatomic Pathology, School of Medicine, State University of Campinas, São Paulo, Brazil.
authors.forename: Albina
authors.initials: A
authors.lastname: Altemani
authors.affiliation: Department of Oral and Maxillofacial Pathology, School of Dentistry, University of São Paulo, São Paulo, Brazil.
authors.forename: Suzana
authors.initials: S
authors.lastname: Sousa
mesh_terms: D000199:Actins / Q000378:metabolism; D000230:Adenocarcinoma / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D000328:Adult; D000368:Aged; D000465:Algorithms; D014408:Biomarkers, Tumor / Q000378:metabolism*; D001706:Biopsy; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D053547:Keratin-14 / Q000378:metabolism; D053552:Keratin-7 / Q000378:metabolism; D007633:Keratins / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D009418:S100 Proteins / Q000378:metabolism; D012468:Salivary Gland Neoplasms / Q000175:diagnosis* / Q000378:metabolism* / Q000473:pathology; D014746:Vimentin / Q000378:metabolism
chemical_list: C541116:ACTA2 protein, human; D000199:Actins; D014408:Biomarkers, Tumor; D053547:Keratin-14; D053552:Keratin-7; D009418:S100 Proteins; D014746:Vimentin; D007633:Keratins
keywords: biopsy; immunohistochemistry; polymorphous low-grade adenocarcinoma; salivary gland tumours; surgical pathology