Germ cell tumors
Yolk sac tumor

Topic Completed: 16 August 2018

Minor changes: 21 October 2020

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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 January 22nd, 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

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.

Comment Here

Reference: Yolk sac tumor
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