Mixed epithelial and mesenchymal tumors
Müllerian adenosarcoma

Topic Completed: 1 March 2018

Minor changes: 11 August 2020

Copyright: 2003-2018, PathologyOutlines.com, Inc.

PubMed Search: Uterus stromal tumors adenosarcoma

Özlem Isiksacan Özen, M.D.
Ayse Ayhan, M.D., Ph.D.
Page views in 2020: 7,896
Page views in 2021 to date: 417
Cite this page: Özen Ö. Müllerian adenosarcoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/uterusadenosarcoma.html. Accessed January 22nd, 2021.
Definition / general
Essential features
  • Mixed tumor with a neoplastic malignant mesenchymal component and an accompanying nonneoplastic (benign) epithelial component, as demonstrated in recent molecular studies (J Pathol 2016;238:381)
ICD coding
Clinical features
  • Obtain a sufficient endometrial biopsy (pipelle or D&C)
  • Apply routine histopathologic criteria; immunohistochemistry has a limited role
Prognostic factors
Case reports
Clinical images

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Mass protruding through cervix

Gross description
  • Usually forms polypoid masses ranging from 1 - 20 cm (mean 5 - 6.5 cm)
  • Typically fills the endometrial cavity and may project into the endocervical canal
  • Rarely mural and serosal
  • A cauliflower-like appearance may be seen
  • Cut surface is solid, white to tan in color with small cysts containing watery or mucoid fluid
  • Soft and fleshy with areas of hemorrhage or necrosis if sarcomatous overgrowth or high grade sarcoma is present
Gross images

Contributed by Aysha Mubeen, M.D.

Case #451

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Cut specimen of uterus and tumor

Endometrial polyp

Hysterectomy specimen

Microscopic (histologic) description
  • Low power reveals a biphasic tumor with intimally admixed glands and prominent stroma throughout
  • Morphologic features diagnostic of adenosarcoma are:
    • Intraglandular growth with projections narrowing the glandular lumens, imparting a leaf-like (phyllodes-like) architecture
    • Periglandular stromal condensation (cuffing)
    • Rigid cystic dilation
    • Mitotic activity ≥ 2 mitoses / 10 HPFs
    • Stromal cytologic atypia
      • Low grade adenosarcomas have monotonous stromal nuclei with mild to moderate atypia (similar to that seen in low grade endometrial stromal sarcoma)
      • High grade adenosarcomas have pleomorphic, markedly atypical nuclei, noticeable at low power magnification and ≥ 2x the size of an endothelial cell nucleus (Am J Surg Pathol 2017;41:1513)
      • They are usually associated with sarcomatous overgrowth and heterologous (rhabdomyosarcoma) differentiation
  • At least 2 of these features must be present diffusely throughout the tumor in order to make the diagnosis of adenosarcoma
  • Epithelium of the glands is usually endometrioid but often shows mucinous, squamous or tubal metaplasia and may show mild to moderate atypia
  • Stroma may show hyalinization, elastosis, edema or myxoid change
  • Sarcomatous overgrowth: presence of sarcoma (without any epithelial component) in > 25% of the tumor, most frequently homologous high grade sarcoma, associated with deeper myometrial involvement and lymphovascular invasion
  • Heterologous elements, most commonly rhabdomyosarcoma, may be present, particularly in the setting of sarcomatous overgrowth and high grade morphology
  • Other types of heterologous differentiation, such as immature cartilage, sex cord-like differentiation or smooth muscle metaplasia may be present
Microscopic (histologic) images

Contributed by Ayse Ayhan, M.D., Ph.D.
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Biphasic tumor

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Periglandular cuff

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Intraglandular papillae

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Stromal mitoses

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Squamous metaplasia

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Sarcomatous overgrowth

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Heterologous elements

Cytology images

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Denuded malignant cells with variable sizes

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Dense clusters of polymorphic tumor cells

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Long oval, hyperchromatic nuclei with 1+ nucleoli (Pap)

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Partly denuded tumor cells with fragile cytoplasm

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Tumor cells have variable sizes

Positive stains
Negative stains
Molecular / cytogenetics description
Differential diagnosis
  • Endometrial polyp: most adenosarcomas are polypoid, and can be mistaken for an endometrial polyp
  • Likewise, some endometrial polyps may display features suggestive of adenosarcoma
    • Endometrial polyps are characterized by uniformly increased cellularity of the stroma lacking periglandular cuffing, cytologic atypia or mitotic activity
    • Polyps with focal atypical features (leaf-like growth, periglandular condensation, atypia, mitoses) have an indolent outcome, and are referred currently as polyps with unusual features (Am J Surg Pathol 2015;39:116)
    • Diagnosis of adenosarcoma requires the presence of diagnostic characteristics diffusely throughout the tumor
  • Adenofibroma: an exceedingly rare biphasic tumor that should be diagnosed only in a well sampled tumor removed totally
    • Diffusely paucicellular stroma with no periglandular cuffing, no stromal atypia and absent or rare mitotic figures < 2 MF/10 HPF
  • Adenomyoma: grossly well circumscribed and the stromal component is made of smooth muscle cells that form fascicles identical to that of a leiomyoma
  • Atypical polypoid adenomyoma: stroma is fibromyomatous and glands have squamous metaplasia
  • Benign endometrial polyp: characterized by uniformly increased cellularity of the stroma lacking periglandular cuffing, cytologic atypia or mitotic activity
  • Carcinosarcoma: glandular component is frankly carcinomatous and high grade
    • Phenomenon of carcinoma arising in an adenosarcoma has been described
    • In these cases the carcinomatous component is localized, and the benign glandular component of adenosarcoma can be appreciated elsewhere
    • Moreover, the carcinoma is usually low grade endometrioid, unlike carcinosarcoma (Mod Pathol 2018;31:418)
  • Embryonal rhabdomyosarcoma: most commonly occurs in the cervix of younger women and girls (mean 18 years)
    • May contain entrapped glands which are surrounded by cuffs of tumor cells, resulting in a cambium layer
    • Entrapped glands are confined to the surface and leaf-like pattern typical of adenosarcoma is absent
    • Malignant stroma away from the cambium layer is hypocellular, edematous or myxoid alternating with small blue aggregates of neoplastic cells
  • Endometrial stromal sarcoma (when glandular elements or entrapped benign endometrial glands are present):
    • Glands in endometrial stromal tumors are usually scant and towards the periphery of the tumor and lack the periglandular stromal condensation and uniform distribution throughout the tumor seen in adenosarcoma
    • Neoplastic stroma permeates the myometrium with a tongue-like pattern in contrast to the destructive infiltration seen in adenosarcoma
    • Immunohistochemistry is not helpful as it shows an overlapping profile
  • Polypoid endometriosis: composed of endometrial stroma and endometrial type glands that may be cystically dilated; it lacks the typical periglandular cuffs, intraglandular stromal papillae or stromal cytologic atypia
Board review style question #1
    Adenosarcoma of the female genital tract:

  1. Differs from adenofibroma by showing marked cellularity (including periglandular cuffs), any degree of stromal cell atypia and ≥ 2 mitotic figures per 10 high powered fields.
  2. Is associated with a good outcome even if myometrial invasion and sarcomatous overgrowth are present.
  3. Is classified as an "adenosarcoma with sarcomatous overgrowth” if a high grade sarcoma is seen in > 10% of the tumor.
  4. Is composed of glands with severe cytological atypia and a cellular low grade malignant stroma.
  5. Never shows any heterologous component while almost half of carcinosarcomas show this feature.
Board review style answer #1
A. Differs from adenofibroma by showing marked cellularity (including periglandular cuffs), any degree of stromal cell atypia and ≥ 2 mitotic figures per 10 high powered fields. Adenosarcoma is a biphasic tumor composed of benign appearing epithelium and a cellular low grade malignant stroma. The main differential diagnosis includes adenofibroma and it differs from adenofibroma by showing marked cellularity (including periglandular cuffs), any degree of stromal cell atypia and ≥ 2 mitotic figures per 10 high powered fields. The tumor is classified as an adenosarcoma with sarcomatous overgrowth when at least 25% of the tumor is composed of pure sarcoma. Adenosarcoma is frequently associated with a good outcome if confined to the endometrium. Otherwise deep myometrial invasion, high grade cytomorphology and sarcomatous overgrowth predict a poor prognosis. Heterologous elements, most commonly rhabdomyosarcoma, may also be present especially in adenosarcoma with sarcomatous overgrowth.
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