Germ cell tumors

Struma ovarii

Editor-in-Chief: Debra L. Zynger, M.D.
Sharon Song, M.D., M.S.
M. Carolina Reyes, M.D.

Last author update: 26 August 2019
Last staff update: 16 May 2023 (update in progress)

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PubMed search: Ovary[TIAB] struma ovarii[TI]

Sharon Song, M.D., M.S.
M. Carolina Reyes, M.D.
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Cite this page: Song S, Reyes MC. Struma ovarii. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/ovarytumorstruma.html. Accessed June 6th, 2023.
Definition / general
  • Monodermal ovarian teratoma primarily (> 50%) or exclusively composed of benign thyroid tissue
  • Any mature teratoma with malignant thyroid tissue
Essential features
  • Ovarian teratoma either composed predominantly or exclusively of benign thyroid tissue or with any amount of malignant thyroid tissue
  • Most common thyroid malignancy to occur in struma ovarii is papillary thyroid carcinoma, followed by follicular carcinoma
ICD coding
  • ICD-10: D27.9 - benign neoplasm of unspecified ovary
  • ICD-10: C56 - malignant neoplasm of ovary
  • Most common type of monodermal teratoma
  • Accounts for 3% of ovarian teratomas (Pathol 2007;39:139)
  • Usually presents in the fifth decade
  • Ovary
Pathophysiology / etiology
  • Unknown at this time
Clinical features
  • Diagnosis is made by microscopic examination of resected tissue
Radiology description
Radiology images

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Left adnexal mass

Prognostic factors
  • Most cases have a good prognosis, even when malignancy is present
Case reports
  • Oophorectomy
  • Surgery for malignant struma ovarii may include total abdominal hysterectomy and bilateral salpingo-oophorectomy with complete staging (Gynecol Oncol 2004;94:835)
Gross description
  • Typically unilateral and solid with a gelatinous, red-brown to green cut surface; may show goiter-like multinodular or cystic change (Am J Surg Pathol 1994;18:785)
Gross images

Contributed by Kseniya Korchagina, M.D.

Cystic teratoma

AFIP images

Solid and cystic

Reddish brown solid mass

Cystic tumor

Frozen section description
  • Frozen section sample usually shows a mature teratoma or benign thyroid tissue; rarely, a possible malignant component may be detected
Microscopic (histologic) description
  • Variably sized macro and microfollicles often containing colloid
  • Other architectural patterns include solid areas composed of cells with clear to oxyphilic cytoplasm, trabeculae, cords and pseudotubular structures
  • Rarely, stroma in between follicles may be fibrotic or edematous; peripheral stromal leutinization may also be seen
  • Adenomatous hyperplasia or proliferative changes may be seen, such as areas of densely packed follicles or papillary formations lacking nuclear features of papillary thyroid carcinoma
  • Birefringent calcium oxalate crystals may be seen in colloid
  • Most commonly associated malignancy is papillary thyroid carcinoma, cytologically characterized by crowded and overlapping elongated nuclei with irregular contours and chromatin clearing, usually with papillary or follicular architecture
  • Follicular carcinoma is the second most common malignancy; since ovarian lesions typically lack capsule, demonstration of tumor invasion into surrounding ovarian tissue, vascular invasion or metastases is needed as evidence of malignancy
  • Uncommonly associated with the more recently described highly differentiated follicular carcinoma of ovarian origin, characterized by extraovarian spread of thyroid elements histologically resembling nonneoplastic thyroid tissue (Int J Gynecol Pathol 2008;27:213)
  • Undifferentiated (anaplastic) carcinoma and medullary carcinoma have also been described in association with struma ovarii
Microscopic (histologic) images

Contributed by Sharon Song, M.S., M.D.

Follicular variant PTC

Capsular invasion

TTF1 stain

Contributed by Kseniya Korchagina, M.D.

Papillary thyroid carcinoma in struma ovarii

AFIP images

Macrofollicular, microfollicular and solid areas

Solid tubular pattern

Oxyphilic cells arranged in nests

With peripheral formation of lutein cells

Resembling clear cell carcinoma

Cystic tumor


With papillary carcinoma

Cytology description
Negative stains
Molecular / cytogenetics description
Sample pathology report
  • Ovary and fallopian tube, left, salpingo-oophorectomy:
    • Struma ovarii, 4.5 cm
  • Ovary and fallopian tube, left, salpingo-oophorectomy:
    • Papillary thyroid carcinoma, follicular and papillary growth patterns, 1.1 cm, arising in a background of struma ovarii
Differential diagnosis
Board review style question #1
What type of crystals may be seen in struma ovarii?

  1. Calcium carbonate
  2. Calcium oxalate
  3. Calcium phosphate
  4. Triple phosphate
  5. Tyrosine
Board review style answer #1
B. Calcium oxalate crystals may be identified in colloid

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Reference: Struma ovarii
Board review style question #2
Which laboratory marker may be elevated with struma ovarii?

  1. Alpha-fetoprotein (AFP)
  2. CA125
  3. CEA
  4. hCG
  5. PLAP
Board review style answer #2
B. CA125 is a widely accepted biomarker for ovarian cancers that can also be elevated in many other conditions, such as menstruation, endometriosis, pregnancy, pelvic inflammatory disease, fibroids, liver disease and tumors of the endometrium, breasts and lungs. It can be increased in up to 30% of struma ovarii.

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Reference: Struma ovarii
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