Polymorphous adenocarcinoma

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Polymorphous low-grade adenocarcinoma, abbreviated PLGA, is a rare malignant salivary gland tumour.

Polymorphous adenocarcinoma
Diagnosis in short

PLGA. H&E stain.

LM low-grade cytology - nuclei ovoid & small, small nucleoli, powdery chromatin (papillary thyroid carcinoma-like appearance); eosinophilic cytoplasm; variable architecture - often small nests, classically has whorling ("eye-of-storm") pattern and single file pattern
LM DDx adenoid cystic carcinoma, pleomorphic adenoma, cribriform adenocarcinoma of the minor salivary gland
Site oral cavity, salivary gland

Prevalence rare

General

  • Almost exclusively in the oral cavity.
    • Classically found in the palate -- 60% of PLGAs in palate.
  • Tumour of the minor salivary glands.
  • Always a low-grade tumour - by definition.
  • Female:male ~= 2:1.
  • Older people ~50-70 years old.

Microscopic

Features:[1]

  • Architecture: often small nests, may be targetoid.
    • Classically has whorling with eye-of-storm & single file.
  • Cytologically monotonous (uniform) with variable architecture - key feature.
  • Indistinct cell borders.

DDx:

Images

IHC

Features:[3]

  • S100 +ve.
  • CK7 +ve.
  • Vimentin +ve.

Others:

  • GFAP +ve/-ve.
  • BCL2 +ve/-ve.
  • Generally negative for myoepithelial markers (calponin, actin) - useful if negative.

See also

References

  1. Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 74. ISBN 978-0781765275.
  2. Skalova, A.; Sima, R.; Kaspirkova-Nemcova, J.; Simpson, RH.; Elmberger, G.; Leivo, I.; Di Palma, S.; Jirasek, T. et al. (Aug 2011). "Cribriform adenocarcinoma of minor salivary gland origin principally affecting the tongue: characterization of new entity.". Am J Surg Pathol 35 (8): 1168-76. doi:10.1097/PAS.0b013e31821e1f54. PMID 21716087.
  3. de Araujo, VC.; Passador-Santos, F.; Turssi, C.; Soares, AB.; de Araujo, NS. (2013). "Polymorphous low-grade adenocarcinoma: an analysis of epidemiological studies and hints for pathologists.". Diagn Pathol 8: 6. doi:10.1186/1746-1596-8-6. PMID 23320410.