Salivary glands
Epithelial / myoepithelial tumors
Polymorphous low grade adenocarcinoma

Author: Adriana Handra-Luca, M.D. (see Authors page)

Revised: 16 March 2018, last major update September 2012

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PubMed Search: Polymorphous low grade adenocarcinoma[TI] salivary glands

Cite this page: Handra-Luca, A. Polymorphous low grade adenocarcinoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/salivaryglandsPLGA.html. Accessed July 16th, 2018.
Definition / general
  • Common tumor of palate with infiltrative growth, multiple architectural growth patterns and cellular uniformity, first described in 1983 (Oral Surg Oral Med Oral Pathol 1983;56:157)
  • Also called terminal duct carcinoma, lobular carcinoma, low grade papillary adenocarcinoma
  • 10% of minor salivary gland tumors but only 1% of all malignant salivary gland tumors
Clinical features
  • #2 most common palate tumor (after adenoid cystic carcinoma); less common in Japanese
  • In major salivary glands, usually associated with pleomorphic adenoma
  • Median age 54 years, range 22 - 71 years, 2/3 women
  • Rare in teenagers but aggressive
  • Slow growing, not painful
  • More than focal papillary growth is associated with cervical nodal metastases
  • Difficult diagnosis on biopsy, frozen section or fine needle aspiration (Arch Pathol Lab Med 2009;133:1763)
Treatment
  • Conservative wide excision
  • 9 - 30% recur, nodal metastases in 9 - 15%, 10% have distant metastases (lung) or tumor related death
  • Long term followup required (Am J Surg Pathol 2000;24:1319)
  • Positive or unknown surgical margins are associated with local recurrence
Gross description
  • Exophytic, may be ulcerated
  • Average size 2 cm
Microscopic (histologic) description
  • Triad of infiltrative growth, multiple architectural growth patterns, cellular uniformity
  • Nonencapsulated but often well circumscribed tumor with diverse (polymorphous) growth patterns (cribriform, fascicular, microcystic, mixed, papillary [focal], pseudoadenoid cystic [without true lumens], single file, solid, strand-like, tubular) (Am J Surg Pathol 1984;8:367)
  • Infiltrative borders as small islands and tubules
  • Mucoid and hyaline stroma (may contain calcifications)
  • Cells have only mild atypia with uniform, bland nuclei (occasional mucus, clear or oncocytic cells) but with perineurial invasion (prominent, frequent, targetoid pattern) common around small nerves
  • No / rare mitotic figures, rare tumor necrosis
  • High grade transformation shows atyipia, necrosis, mitoses, MIB index, p53 overexpression
Microscopic (histologic) images

Images hosted on other servers:

Various images

Positive stains
Negative stains
Molecular / cytogenetics description
  • Diploid but chromosome 12 abnormalities
  • No t(11,19)
  • 6q, 11q deletions in metastatic cases, few copy number alterations
Differential diagnosis