Sex cord stromal tumors


Editorial Board Member: Gulisa Turashvili, M.D., Ph.D.
Deputy Editor-in-Chief: Jennifer A. Bennett, M.D.
Victoria Collins, M.D.
Tamara Kalir, M.D., Ph.D.

Last author update: 25 June 2021
Last staff update: 24 August 2022

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PubMed search: Ovarian thecoma [TI]

Victoria Collins, M.D.
Tamara Kalir, M.D., Ph.D.
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Cite this page: Collins V, Kalir T. Thecoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/ovarytumorthecoma.html. Accessed June 8th, 2023.
Definition / general
  • Ovarian stromal neoplasm, almost always benign, composed of cells resembling theca cells
Essential features
  • Almost always benign
  • Usually occurs in postmenopausal women who present with uterine bleeding
  • Histology shows a predominant population of cells with ovoid to round nuclei and pale gray cytoplasm
  • Reticulin stain and molecular testing for FOXL2 mutation help distinguish thecoma from adult granulosa cell tumor
  • Theca cell tumor
ICD coding
  • ICD-O: 8600/0 - thecoma, NOS
  • ICD-10: D27 - benign neoplasm of ovary
  • ICD-11: 2F32.Y & XH34A0 - other specified benign neoplasm of ovary & thecoma, NOS
  • Ovary
  • Unknown
Clinical features
  • May be discovered incidentally
  • Most common symptom is postmenopausal bleeding (Am J Surg Pathol 2014;38:1023)
  • Symptoms can be related to mass: pelvic pain / pressure
  • May present with estrogenic or androgenic manifestations
  • Associated with endometrial hyperplasia and malignancy
  • Histologic examination
Radiology description
Radiology images

Images hosted on other servers:

Bilateral thecomas on MRI

Prognostic factors
  • Thecomas are almost always benign but may be associated with endometrial malignancy
Case reports
Clinical images

Images hosted on other servers:

Bitemporal hair loss

Frontal balding and hirsutism

Gross description
  • Usually unilateral
  • Most are < 5 cm
  • Solid, yellow and lobulated or white with focal yellow areas
  • Occasionally cystic change and hemorrhage are present
  • Necrosis is rare (Am J Surg Pathol 2014;38:1023)
Gross images

Contributed by Victoria Collins, M.D., Tamara Kalir, M.D., Ph.D. and AFIP images

Well circumscribed, yellow-tan mass

Lobulated and yellow

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Yellow, lobulated mass

Frozen section description
  • Sheets of oval to round cells with moderate to abundant pale gray cytoplasm
  • Bilaterality should raise suspicion for metastasis
Frozen section images

Contributed by Victoria Collins, M.D. and Tamara Kalir, M.D., Ph.D.

Spindled to ovoid cells

Moderate cytoplasm

Microscopic (histologic) description
  • Predominant population of cells showing ovoid to round nuclei and pale gray cytoplasm, which can be abundant
  • Minor component of the tumor may have spindled nuclei, reflecting overlap between fibroma and thecoma
  • Indistinct cell membranes impart a syncytial appearance
  • Diffuse or nodular growth pattern
  • Absent or minimal nuclear atypia
  • Mitotic rate usually < 5/10 high power fields
  • Hyaline plaques
  • Cytoplasmic lipid vacuoles may be present but are not essential
  • May show aggregates of cells with brightly eosinophilic cytoplasm (lutein cells)
  • Calcification is more common in young patients (Int J Gynecol Pathol 1988;7:343)
  • Uncommon features include keloid-like sclerosis, nuclear grooves, bizarre nuclear atypia (Am J Surg Pathol 2014;38:1023)
  • Rarely contains a minor component of sex cord elements (Int J Gynecol Pathol 1983;2:227)
  • Malignant thecoma: very rare, diagnosis requires diffuse moderate to severe nuclear atypia and high mitotic rate (> 4/10 high power fields) (Am J Surg Pathol 2011;35:e15)
Microscopic (histologic) images

Contributed by Victoria Collins, M.D. and Tamara Kalir, M.D., Ph.D.

Well circumscribed

Ovoid to round cells

Mild nuclear atypia

Thecoma and fibroma areas

Cystic change

Hyaline plaques



AFIP images

Vacuolated tumor cells

Stromal calcification

Oil red O stain

Virtual slides

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Thecoma, with cystic change

Thecoma, reticulin stain

Electron microscopy description
  • Cytoplasmic lipid (Ultrastruct Pathol 1992;16:363)
  • Type I cells: dispersed chromatin, basal lamina investment of each cell, coiled / branching rough endoplasmic reticulum, sparse smooth endoplasmic reticulum, irregular mitochondria
  • Type II cells: degenerative changes, large round mitochondria with incomplete cristae and centers displaced by microfilaments (Hum Pathol 1984;15:153)
Molecular / cytogenetics description

Thecoma of ovary

Ovarian pathology

Sample pathology report
  • Right ovary and fallopian tube, salpingo-oophorectomy:
    • Ovarian thecoma
    • Fallopian tube with no significant pathologic changes
Differential diagnosis
Board review style question #1

A 59 year old woman presents with bitemporal hair loss and hirsutism. Exploratory laparotomy reveals a 6 cm right ovarian mass, which is resected. Which of the following is true of this tumor?

  1. 30 - 40% are malignant
  2. CD10 positive
  3. Harbors a FOXL2 mutation
  4. Reticulin stain shows a pericellular pattern
Board review style answer #1
D. Reticulin stain shows a pericellular pattern

Comment Here

Reference: Thecoma
Board review style question #2

A 62 year old woman presents with postmenopausal bleeding and on workup is found to have a 5 cm left ovarian mass. Which of the following immunostains is typically positive in this tumor?

  1. AE1 / AE3
  2. CD99
  3. Cyclin D1
  4. DOG1
  5. Inhibin
Board review style answer #2
E. Inhibin

Comment Here

Reference: Thecoma
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