Fallopian tubes & broad ligament

Fallopian tube epithelial tumors

Serous tubal intraepithelial carcinoma

Editorial Board Member: Gulisa Turashvili, M.D., Ph.D.
Editor-in-Chief: Debra L. Zynger, M.D.
Aysha Mubeen, M.D.
Arun Gopinath, M.D.

Last author update: 20 April 2022
Last staff update: 20 April 2022

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PubMed Search: Serous tubal intraepithelial carcinoma

Aysha Mubeen, M.D.
Arun Gopinath, M.D.
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Cite this page: Mubeen A, Gopinath A. Serous tubal intraepithelial carcinoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/fallopiantubesstic.html. Accessed February 23rd, 2024.
Definition / general
  • Lesion that is limited to the fallopian tube epithelium and a precursor to extrauterine (pelvic) high grade serous carcinoma
Essential features
  • Confined to epithelium
  • Histologic features: significant atypia, architectural alterations, high proliferative index and mutant pattern of p53 staining
  • Important precursor lesion to recognize, as it is a criterion for assigning fallopian tube as primary site of high grade tubo-ovarian serous carcinoma irrespective of presence and size of ovarian and peritoneal disease (Histopathology 2015;67:331)
  • Various terms used to describe a spectrum of tubal epithelial alterations:
    • Secretory cell outgrowths (SCOUTs): secretory cell expansion with variable ciliation (type 1 / tubal differentiation and type 2 / endometrioid differentiation), wild type p53 staining
    • p53 signature: histologically normal epithelium (at least 12 cells) with mutant pattern p53 staining and low proliferation index (MIB1) (typically less than 10%)
    • Serous tubal intraepithelial lesion (STIL): abnormal histology (high N/C but preserved polarity), mutant p53 and variable MIB1; STIL is regarded as a lesion of uncertain significance and diagnostic features fall short of STIC
    • Serous tubal intraepithelial carcinoma (STIC): abnormal histology (high N/C, loss of polarity, lack of ciliated cells), mutant pattern p53 staining and high proliferation index (MIB1)
ICD coding
  • ICD-10: N83.9 - fallopian tube disorder
  • Patients with hereditary BRCA mutation have a high risk of high grade serous carcinoma
  • Incidence of STIC in risk reducing salpingo-oophorectomies in BRCA+ women is 5 - 8% (Gynecol Oncol 2006;100:58)
  • Fallopian tube fimbria is the most common site of origin
Clinical features
  • Usually discovered incidentally during routine surgery or risk reducing prophylactic salpingo-oophorectomies
  • May be seen adjacent to invasive carcinoma
  • Reference: Gynecol Oncol 2017;146:69
  • Careful morphologic evaluation is key to the diagnosis; immunohistochemistry (p53 and MIB1) is only supportive
  • Gross protocol (sectioning and extensively examining the fimbria [SEE-FIM]) influences ability to diagnose (Am J Surg Pathol 2006;30:230):
    • Amputation and longitudinal sectioning of the infundibulum and fimbrial segment (distal 2 cm) allows maximal exposure of the tubal plicae; isthmus and ampulla are cut transversely at 2 - 3 mm intervals
    • Entire fallopian tube should be submitted for evaluation in women with BRCA mutations or strong family history of ovarian carcinoma
    • Extensively examine the fimbriated end
    • Controversial role of multiple levels with 1 study finding no impact and another study reporting 25% missed with a single section (Am J Surg Pathol 2009;33:1878, Int J Gynecol Pathol 2013;32:353)
  • STIC is staged as pathologic stage pT1
Case reports
  • No current consensus among gynecologic oncologists regarding appropriate management of incidental STIC
  • Patients have been managed by surgical staging / peritoneal washings / chemotherapy or follow up without additional intervention
  • Yield of surgical staging is low and short term clinical outcomes are favorable
  • Individualized management is warranted until additional data become available (Int J Gynecol Cancer 2013;23:1603)
Gross description
  • Not evident on gross examination
Microscopic (histologic) description
  • Epithelial stratification
  • Lack of ciliated cells (Mod Pathol 2017;30:710)
  • High N/C ratio
  • Nuclear pleomorphism, hyperchromasia, prominent nucleoli
  • Loss of polarity (may be focal)
  • Epithelial fractures (Adv Anat Pathol 2010;17:293)
  • Exfoliation of small epithelial clusters
Microscopic (histologic) images

Contributed by Aysha Mubeen, M.D.

Basophilic appearance

Architectural and cytological atypia

STIC in contrast with adjacent normal tubal epithelium

Prominent atypia and multilayering


Virtual slides

Images hosted on other servers:

Focal epithelial stratification,
loss of polarity,
hyperchromatic and
pleomorphic nuclei

Cytology description
Positive stains
Sample pathology report
  • Bilateral fallopian tubes, salpingectomy:
    • Right fallopian tube with serous tubal intraepithelial carcinoma (see comment)
    • Left fallopian tube with no pathologic change
    • Comment: Immunostain for p53 is diffusely and strongly positive in the lesional cells. Ki67 index is > 10%.
Differential diagnosis
Board review style question #1
Which fallopian tube lesion appears normal on histology but shows a mutant pattern of p53 immunostaining?

  1. p53 signature
  2. Reactive atypia
  3. Secretory cell outgrowth (SCOUT)
  4. Serous tubal intraepithelial carcinoma (STIC)
Board review style answer #1
Board review style question #2

The grossing protocol for examination of the fallopian tube to identify the diagnosis in the photomicrograph should

  1. Ensure complete evaluation of the fallopian tube in all cases
  2. Increase detection of precursor lesions in at risk women
  3. Require multistep levels in at risk women
  4. Require tangential sectioning of the infundibulum and fimbrial segment to allow maximal exposure
Board review style answer #2
B. Increase detection of precursor lesions in at risk women. Serous tubal intraepithelial carcinoma is shown in the photomicrograph.

Comment Here

Reference: Serous tubal intraepithelial carcinoma
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