Germ cell tumors
Yolk sac tumor

Editorial Board Member: Carlos Parra-Herran, M.D.
Editor-in-Chief: Debra L. Zynger, M.D.
Sharon Song, M.S., M.D.
M. Carolina Reyes, M.D.

Topic Completed: 16 August 2018

Minor changes: 27 April 2021

Copyright: 2002-2021, PathologyOutlines.com, Inc.

PubMed Search: Ovarian yolk sac tumor[TIAB]

Sharon Song, M.S., M.D.
M. Carolina Reyes, M.D.
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Cite this page: Song S, Reyes MC. Yolk sac tumor. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/ovarytumoryolksac.html. Accessed May 6th, 2021.
Definition / general
  • A malignant primitive germ cell tumor that shows various patterns of endodermal differentiation (primitive gut, mesenchyme, secondary yolk sac), including their derivatives (intestine, liver, lung)
Essential features
  • Numerous morphologic patterns
  • Usually occur as pure neoplasms but occasionally a component of a mixed germ cell tumor
  • Often associated with elevated alpha fetoprotein (AFP)
  • Primitive endodermal tumor (recently proposed)
  • Endodermal sinus tumor (not recommended)
  • The term "somatic yolk sac tumor" has been used to describe tumor associated with an epithelial neoplasm (usually high grade, including high grade serous carcinoma, clear cell carcinoma, carcinosarcoma); the yolk sac component likely arises from the carcinoma (rather than a true mixed or "collision" tumor) (Histopathology 2016;69:739, Int J Gynecol Pathol 2011;30:442)
ICD coding
  • C56.9: Malignant neoplasm of unspecified ovary
  • Unknown
Clinical features
  • Elevated serum levels of alpha fetoprotein (AFP)
Radiology description
  • Usually appears as a large solid cystic mass with heterogeneous enhancement, enlarged intratumoral vessels with hemorrhage and capsular tear (Acta Radiol 2016;57:98)
  • CT features that are useful for differentiating yolk sac tumors from other ovarian tumors include a mixed solid-cystic nature, intratumoral hemorrhage, marked enhancement and dilated intratumoral vessels (Sci Rep 2015;5:11000)
  • When present in association with a teratoma, may see intratumoral calcification and fatty tissue (rare)
Radiology images

Images hosted on other servers:

Large mass with ascites

Cystic mass

Case reports
  • Unilateral salpingo-oophorectomy (Eur J Surg Oncol 2006;32:1063)
  • Adjuvant chemotherapy
    • Excellent response
    • Less responsive when associated with a somatic neoplasm
Clinical images

Images hosted on other servers:

Large left ovary tumor

Gross description
  • Large, encapsulated mass with smooth and glistening surface; 25% are ruptured (Int J Surg Pathol 2014;22:677)
  • Fleshy, gray-yellow, variably cystic and friable cut surface, often with areas of hemorrhage and necrosis
  • When part of a mixed germ cell tumor, other components such as a mature cystic teratoma or dysgerminoma are often grossly recognizable
  • Honeycomb appearance if polyvesicular vitelline component is present
Gross images

Contributed by Debra L. Zynger, M.D.
Smooth, nodular exterior

Smooth, nodular exterior

Gelatinous cut surface

Gelatinous cut surface

AFIP images

Gelatinous cystic surface

Honeycomb surface (polyvesicular vitelline pattern)

Microscopic (histologic) description
  • Various histologic patterns
  • Reticular / microcystic:
    • Most common and characteristic pattern
    • Loose network of anastomosing channels that focally expand to form variably sized cysts; these spaces are lined by primitive tumor cells with varying amounts of clear, glycogenated cytoplasm, occasionally containing lipid
    • Microcysts may contain eosinophilic hyaline globules and amorphous, eosinophilic acellular basement membrane material
    • Loose, hypocellular and myxoid stroma
  • Endodermal sinus:
    • Contain Schiller-Duval sinuses or bodies - tubulopapillary sinusoidal structures with central vascular core and cuboidal to columnar epithelial-like cell lining
      • Diagnostic of entity when present
      • Seen in only 20% of tumors
  • Other patterns (Histopathology 2012;60:1023):
    • Polyvesicular vitelline: prominent cysts lined by flattened to columnar cells within a variably cellular stroma, occasionally with eccentric constriction (resembling the division of the primary yolk sac vesicle)
    • Solid: sheet-like arrangement of cells with large nuclei and well defined borders; cells may have abundant clear cytoplasm or may be more blastema-like with smaller cells and scant cytoplasm
    • Hepatoid: scattered small clusters or cords of large polygonal cells with abundant eosinophilic cytoplasm and prominent nucleoli, separated by thin fibrous bands
    • Intestinal: primitive cells forming glands separated by stroma; lined by mucinous columnar cells, goblet cells and rarely, Paneth cells
    • Endometrioid: glandular pattern resembling conventional or secretory endometrial endometrioid carcinoma (subnuclear and sometimes supranuclear vacuoles resembling secretory endometrium)
    • Parietal: extracellular deposits of basement membrane material, usually within reticular foci and surrounding groups of tumor cells
    • Festoon: undulating ribbons, occasionally with a drape-like arrangement
    • Tubular
    • Papillary
Microscopic (histologic) images

Contributed by Sharon Song, M.D.

Reticular / microcystic pattern

Schiller-Duval body

Polyvesicular vitelline pattern

Papillary pattern

Solid pattern

AFP stain

AFIP images

Hepatoid variant

Endometrioid-like glandular variant

Positive stains
Negative stains
Molecular / cytogenetics description
Differential diagnosis
Board review style question #1
Which immunohistochemical markers would help distinguish this ovarian tumor from a dysgerminoma?

  1. CD10
  2. FOXL2
  3. Inhibin
  4. OCT3/4
  5. SALL4
Board review style answer #1
D. This is a yolk sac tumor with a reticular / microcystic pattern. OCT3/4 is positive in all dysgerminomas but most often negative in yolk sac tumors (9% are positive).

Comment Here

Reference: Yolk sac tumor
Board review style question #2
All of the following are features of yolk sac tumors except:

  1. Association with dysgerminoma
  2. Glypican 3 positivity
  3. High AFP levels
  4. Homer Wright rosettes
  5. Most common in young women
Board review style answer #2
D. Homer Wright rosettes are usually seen in entities such as medulloblastoma and primitive neuroectodermal tumors. The pathognomonic entity in yolk sac tumors is the Schiller-Duval body.

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Reference: Yolk sac tumor
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