title: Polymorphous low-grade adenocarcinoma: the University of Pittsburgh experience.
abstract: OBJECTIVE
  To reappraise the clinical and histologic variables associated with a more aggressive outcome in polymorphous low-grade adenocarcinoma (PLGA).
  
  
  METHODS
  Retrospective cohort.
  
  
  METHODS
  University hospital.
  
  
  METHODS
  Twenty-four patients with PLGA treated from January 1, 1973, through December 31, 2005.
  
  
  METHODS
  Analysis of clinical and pathologic variables in 30 biopsy or resection specimens from 24 patients.
  
  
  RESULTS
  Only 4 PLGAs were not initially diagnosed as such. However, 8 non-PLGAs (thus excluded) were incorrectly diagnosed as PLGA. Most carcinomas (14 of 24 [58%]) were palatal. Recurrent carcinomas had a significantly higher mitotic rate (2.7 mitoses per 10 high-power fields) compared with primary tumors (1.2 mitoses per high-power fields, P = .046), and 3 of 7 (43%) recurrences showed progression to an intermediate-grade histologic type. No patient died of disease. Median disease-free survival was 12.8 years. Four of 24 patients (17%) had regional lymph node metastases, 3 with carcinomas of the base of the tongue. One PLGA metastasized to the subcutaneous tissue of the face, orbit, and lungs at 19.6 years. An extrapalatal site was the only significant determinant of disease-free survival (P = .03).
  
  
  CONCLUSIONS
  Diagnosis of PLGA remains a challenge. Extrapalatal carcinomas appear to behave in a more aggressive fashion than those of the palate, and cancer arising from the base of the tongue frequently metastasizes to the cervical lymph nodes, suggesting a role for neck dissection in these patients. Recurrent cancers show evidence of histologic progression, justifying an aggressive approach to achieving initial complete excision.
authors.affiliation: Department of Pathology, University of Pittsburgh School of Medicine, UPMC Presbyterian University Hospital, PA 15213, USA. seethalarr@upmc.edu
authors.forename: Raja R
authors.initials: RR
authors.lastname: Seethala
authors.forename: Jonas T
authors.initials: JT
authors.lastname: Johnson
authors.forename: E Leon
authors.initials: EL
authors.lastname: Barnes
authors.forename: Eugene N
authors.initials: EN
authors.lastname: Myers
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology* / Q000628:therapy; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D003131:Combined Modality Therapy; D005260:Female; D006258:Head and Neck Neoplasms / Q000473:pathology* / Q000628:therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local / Q000473:pathology* / Q000628:therapy; D009367:Neoplasm Staging; D012189:Retrospective Studies; D016896:Treatment Outcome