Uterus
Mixed epithelial and mesenchymal tumors
Atypical polypoid adenomyoma
Author: Vijay Shankar, M.D.
Topic Completed: 1 March 2016
Minor changes: 28 January 2021
Copyright: 2002-2021, PathologyOutlines.com, Inc.
PubMed Search: Atypical polypoid adenomyoma [title]
Table of Contents
Definition / general | Terminology | Epidemiology | Sites | Pathophysiology | Clinical features | Diagnosis | Radiology description | Prognostic factors | Case reports | Treatment | Gross description | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Cytology description | Positive stains | Molecular / cytogenetics description | Differential diagnosisCite this page: Shankar V. Atypical polypoid adenomyoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/uterusapa.html. Accessed March 4th, 2021.
Definition / general
- Biphasic polypoid lesion consisting of a myofibroblastic stromal component and an endometrial intraepithelial neoplasm, typically with squamous metaplasia (Mod Pathol 2000;13:328, Mod Pathol 2000;13:309)
Terminology
- Also called APA, atypical polypoid adenomyofibroma
Epidemiology
- Uncommon
- Mean age 40 years, range 21 - 73 years (Am J Surg Pathol 1996;20:1)
- May occur in women with Turner syndrome (Int J Gynecol Pathol 1987;6:104)
- Rare occurrence in women with Cowden syndrome (Gynecol Oncol Case Rep 2012;2:29)
Sites
- Usually lower uterine segment (Am J Clin Pathol 1986;86:139), rarely fundus
Pathophysiology
- Mechanism unclear, but the endometrial stromal cells are considered to be the precursors of the smooth muscle (J Cancer Ther 2011:4:1)
Clinical features
- Irregular vaginal bleeding
- Incidental finding in the evaluation of infertility
- Brownish discharge per vagina rarely
- May persist or recur, but does not metastasize
- Patients have increased risk for subsequent carcinoma
Diagnosis
- By histopathological examination
Radiology description
- T2 weighted images: slightly hyperintense polypoid mass mixed with markedly hyperintense foci that correspond to islands of metaplastic endometrial foci
- T1 weighted images: tumors are isointense with the myometrium and occasionally have hyperintense cystic foci (J Comput Assist Tomogr 2015;39:32)
Prognostic factors
- Propensity for the development of adenocarcinoma, although the precise mechanism remains poorly understood (Kobe J Med Sci 2014;60:E74)
- The adenocarcinoma may coexist or may develop during long term follow up, which is recommended (Gynecol Oncol Case Rep 2014;8:21)
Case reports
- 35 year old woman with hysteroscopic treatment of atypical polypoid adenomyoma (Fertil Steril 2008;89:456)
- 45 year old woman (Jpn J Radiol 2012;30:606)
- 53 year old woman with incidental endometrial tumor (Arch Pathol Lab Med 2002;126:864)
Treatment
- Hysterectomy if peri / postmenopausal
- More conservative management with complete removal of the tumor and close follow up may be considered for women desiring to preserve their fertility (Fertil Steril 2008;89:456, Gynecol Oncol 2013;129:54)
- The recurrence rate among different modalities of treatment ranges from 10 – 45%
Gross description
- Resembles endometrial polyp, but often sessile with a broader base
- Single, well circumscribed, polypoid mass, often in lower uterine segment
- Very rarely is multiple (Jpn J Radiol 2012;30:606)
- Usually confined to endometrium with a pushing margin
- Remaining endometrium is often unremarkable
Gross images
Images hosted on other servers:
Polypoid mass
Microscopic (histologic) description
- Benign biphasic epithelial and mesenchymal tumor
- Consists of endometrial intraepithelial neoplasm (complex architecture, varying atypia up to severe, cribriform pattern, solid irregular and papillary arrangements), separated by fascicles of bland smooth muscle and fibrous stroma
- No endometrial type stroma and no prominent stromal atypia
- Squamous morules are usually present, may have central necrosis
- Minimal mitotic activity (< 3 per 10 HPF)
- No desmoplasia
- Cases with more prominent fibrous appearance may be called atypical polypoid adenofibroma
- May have coexisting EIN / complex atypical hyperplasia (Diagn Cytopathol 2010;38:527) or well differentiated endometrioid adenocarcinoma (Kobe J Med Sci 2014;60:E74, Gynecol Oncol Case Rep 2012;2:29)
- Cases with markedly complex glands and architectural complexity are designated as APA of low malignant potential (APA-LMP) (Gynecol Endocrinol 2013;29:623)
Microscopic (histologic) images
AFIP images
Fascicles of benign, cellular smooth muscle
Architectural irregularity
Large benign morules
Images hosted on other servers:
Hyperplastic endometrial glands
Squamous metaplasia
Crowded glands
High power
MIB1
Cytology description
- Abnormal proliferation of epithelium and stromal cells of smooth muscle origin (Diagn Cytopathol 2010;38:527)
- Tightly packed, crowded clusters of glandular cells and loose aggregates of smooth muscle stromal cells (Diagn Cytopathol 2000;22:176)
Positive stains
- Stroma: HHF35, alpha-smooth muscle actin, vimentin and trichrome , variable desmin (Histopathology 1995;27:35)
- Variable Ki67 proliferative activity, but usually low
- h-caldesmon is useful in distinguishing APA from myoinvasive endometrioid carcinoma (Int J Gynecol Pathol 2011;30:64)
Molecular / cytogenetics description
- Express HNF-1β, mTOR, and GLUT1 in the glandular component
- β-catenin mutations are common (Hum Pathol 2014;45:33)
- Wild type expression of p53, loss of PTEN, and mutation of KRAS (Am J Surg Pathol 2015;39:1148)
Differential diagnosis
- Adenofibroma
- Adenosarcoma
- Benign endometrial polyps
- Complex atypical endometrial hyperplasia
- Carcinosarcoma: also called MMMT, sarcomatoid carcinoma
- Older women, stroma also malignant, diffuse atypia and increased mitotic activity
- Endometrioid adenocarcinoma, older women, large tumor, grossly invasive into myometrium with hemorrhage, necrosis and desmoplasia
