Fallopian tubes
Tumors
Serous tubal intraepithelial carcinoma (STIC)

Senior Author: Arun Gopinath, M.D.
Editor-in-Chief: Debra Zynger, M.D.
Aysha Mubeen, M.D.
Arun Gopinath, M.D.

Topic Completed: 10 July 2019

Revised: 10 July 2019

Copyright: 2019, PathologyOutlines.com, Inc.

PubMed Search: Serous tubal intraepithelial carcinoma[TI]

Aysha Mubeen, M.D.
Arun Gopinath, M.D.
Page views in 2019 to date: 673
Cite this page: Mubeen A, Gopinath A. Serous tubal intraepithelial carcinoma (STIC). PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/fallopiantubesstic.html. Accessed July 21st, 2019.
Definition / general
  • Lesion limited to the fallopian tube epithelium that is a precursor to extrauterine (pelvic) high grade serous carcinoma
Essential features
  • Confined to epithelium
  • Histologic features: high proliferative index, significant atypia, architectural alterations and strong staining for p53
  • Especially important precursor lesion that 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)
Terminology
  • Various terms used in tubal epithelial alterations are:
    • Secretory cell outgrowths (SCOUTs): secretory cell expansion with variable ciliation
    • p53 signature or serous tubal intraepithelial lesions (STILs): secretory cell outgrowths with strong p53 staining (normal histology)
    • Serous tubal intraepithelial carcinoma (STIC): abnormal histology (high N:C, loss of polarity, lack of ciliated cells, strong and diffuse p53 or rarely completely negative)
ICD coding
  • ICD-10: N83.9 - fallopian tube disorder
Epidemiology
  • Patients with hereditary BRCA mutation have a high risk of ovarian serous cancer
  • Incidence of STIC in risk reducing salpingo-oophorectomies in BRCA+ women is 5 - 8% (Gynecol Oncol 2006;100:58)
Sites
  • Fallopian tube fimbria is the most common site of origin
Pathophysiology
Clinical features
  • Usually discovered incidentally during routine surgery or risk reducing prophylactic salpingo-oophorectomies
  • May be seen adjacent to invasive carcinoma
Diagnosis
  • Examination of tissue is required for the diagnosis; cannot be made with immunostains alone
  • Gross protocol influences ability to diagnose
    • 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 (Am J Surg Pathol 2009;33:1878) and a newer study reporting 25% missed with a single section (Int J Gynecol Pathol 2013;32:353)
Case reports
Treatment
  • No current consensus among gynecologic oncologists regarding appropriate management of incidental STIC
  • Patients have been managed by surgical staging / peritoneal washings / chemotherapy or followup 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
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

p53

Virtual slides

Images hosted on other servers:

Serous tubal intraepithelial carcinoma

Cytology description
Positive stains
  • p53: diffusely positive or negative (null mutation)
  • Ki67 index: high (> 40%, may be > 70% focally)
Molecular / cytogenetics description
  • Mutations in the p53 tumor suppressor gene that retard degradation of the protein product (J Pathol 2019;248:41)
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 > 40%.
Differential diagnosis
Board review question #1
What is the name of a lesion that appears normal on histology but stains positive for p53 immunostain?

  1. p53 signature
  2. Reactive atypia
  3. Secretory cell outgrowth (SCOUT)
  4. Serous tubal intraepithelial carcinoma (STIC)
Board review answer #1
Board review 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 answer #2
B. Increase detection of precursor lesions in at risk women. Serous tubal intraepithelial carcinoma is shown in the photomicrograph.

Reference: Serous tubal intraepithelial carcinoma

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