Serous tumors
Serous borderline tumor, micropapillary variant / noninvasive low grade serous carcinoma

Topic Completed: 1 June 2012

Minor changes: 19 October 2020

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PubMed search: Serous micropapillary carcinoma

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Cite this page: Ehdaivand S. Serous borderline tumor, micropapillary variant / noninvasive low grade serous carcinoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/ovarytumorserousmicropapillary.html. Accessed January 24th, 2021.
Definition / general
  • Also called low grade serous carcinoma
  • Behaves like low grade adenocarcinoma; appear to be derived from serous borderline tumor or adenofibroma
  • Recurs as classic serous carcinoma
  • 10 year survival is 70% versus ~100% for borderline tumors
  • Invasive if destructive infiltrative growth; most are noninvasive
Prognostic factors
  • Survival: dependent on stage and invasiveness of implants
  • Stage I invasive or noninvasive has 100% disease free survival
  • Stage II / III noninvasive or invasive with noninvasive implants has 80% disease free survival
  • Stage II / III noninvasive with invasive implants has 55% 10 year survival
  • Stage II / III invasive with invasive implants has 45% 10 year survival
Microscopic (histologic) description
  • Filigree or cribriform pattern:
    • Filigree pattern of small, uniform, elongated, stroma-poor or stroma-free papillae, at least five times as long as wide, arising directly in a nonhierarchical fashion from large fibrotic, edematous, or myxoid papillary stalks or from cyst walls
    • Or a cribriform pattern of epithelial cells lining the stalks or cyst walls
    • Or both; either or both patterns should be present on a confluent area at least 5 mm in greatest dimension on at least one slide; occasionally also have large macropapillae

  • Noninvasive:
    • Numerous delicate micropapillae (length > 5x width) with no / rare fibrovascular cores
    • Radiates in "medusa" nonhierarchical branching pattern from thick fibrous stalks
    • May be cribriform due to fusion
    • Micropapillae are covered by cuboidal / columnar cells with minimal cytoplasm, variable psammoma bodies, no cilia, no / rare mitotic figures
    • More recurrences but similar survival as serous borderline tumors (Am J Surg Pathol 2002;26:1129)

  • Invasive:
    • By definition, has destructive infiltrative growth
    • Invasive areas may be > 3 mm or larger
    • Stromal invasion is characterized by micropapillae and solid epithelial nests surrounded by a cleft or space and fibroblastic stroma
    • May also have noninvasive component
    • Variable psammoma bodies
    • Rarely mitotic figures or atypical mitotic figures
    • Macropapillary component may signify invasive disease (Am J Surg Pathol 2008;32:1800)
    • Single cells or small clusters of cells appearing to be in spaces within nonreactive stroma are considered to NOT represent stromal invasion
Microscopic (histologic) images

Images hosted on other servers:

Large fibrovascular core entirely surrounded by long, slender micropapillae

Low grade nuclei

Ovary with non-invasive low grade serous carcinoma

Ovary with non-invasive component represented by an APST

Atypical proliferative (borderline) ovarian tumor

Mixture of macro and micropapillae

Molecular / cytogenetics description
  • Chromosomal imbalances intermediate between serous borderline tumors and serous carcinomas (Hum Pathol 2002;33:47)
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