Uterus
Other tumors
Adenomatoid tumor
Last author update: 1 October 2016
Last staff update: 3 March 2023 (update in progress)
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PubMed search: adenomatoid tumor uterus
Table of Contents
Definition / general | Essential features | Terminology | ICD coding | Epidemiology | Sites | Pathophysiology | Etiology | Clinical features | Diagnosis | Laboratory | Radiology description | Prognostic factors | Case reports | Treatment | Gross description | Microscopic (histologic) description | Microscopic (histologic) images | Cytology description | Positive stains | Negative stains | Electron microscopy description | Molecular / cytogenetics description | Differential diagnosis | Additional referencesCite this page: Ardighieri L. Adenomatoid tumor. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/uterusadenomatoid.html. Accessed March 23rd, 2023.
Definition / general
- Benign tumor of mesothelial origin
Essential features
- Uncommon benign tumor, most frequently seen in the genital tract of both sexes
- In the female genital tract: uterus / fallopian tube / ovarian hilus / broad ligament
- In the male genital tract: epididymis / tunica albuginea / spermatic cord / tunica vaginalis, testis and prostate
- Extragenital tumors are rare: adrenal glands (World J Surg Oncol 2014;12:377), / pleura (Respir Med 2015;109:931) / mesentery, mesocolon, peritoneum (APMIS 2008;116:1016) / omentum (Pathol Int 2011;61:681) / appendix (J Obstet Gynaecol Res 2003;29:234) / liver (BMJ Case Rep 2014;2014) / mediastinum (Case Rep Pathol 2016;2016:6898526, Gen Thorac Cardiovasc Surg 2016;64:47) / lymph node (Mayo Clin Proc 2003;78:350) / heart (Cardiovasc Pathol 2002;11:181) / pancreas (Mod Pathol 2003;16:613), umbilicus (Arch Pathol Lab Med 2003;127:e303 and small intestine (Int J Surg Pathol 2015;23:94)
- In the uterus they are commonly asymptomatic
- Typically presents as subserosal or intramural small, solitary nodule
- Usually an incidental finding in resection specimen for unrelated disease (leiomyoma, adenomyosis, endometrial cancer)
Terminology
- Synonyms: benign mesothelioma, benign mesothelial tumor, benign adenomatoid mesothelioma
ICD coding
- 9054 / 0
Epidemiology
- 1.2% of hysterectomy specimen (5% of uterine surgical specimens, but true incidence may be higher due to misdiagnosis and missed diagnosis (Biomed Rep 2013;1:352)
- Multifocal and diffuse in immunosuppressed patients (Int J Gynecol Cancer 2009;19:242)
Sites
- Most common in fundus (close to cornum, outer myometrium, subserosal or intramural (J Obstet Gynaecol India 2015;65:255)
- Rarely may involve the superficial myometrium; eventually may be present in endometrial curettings (Int J Gynecol Pathol 1986;5:69)
Pathophysiology
- Neoplastic rather than reactive (based on molecular, clinical and pathological features)
Etiology
- Derivation from mesothelium:
- Ultrastructural and immunoistochemical studies support its mesothelial nature (Int J Gynecol Pathol 2002;21:34)
- Differentiated mesothelial cells by inclusion or embolization
- Pluripotent müllerian mesenchymal stem cells (Pathol Res Pract 1999;195:605)
Clinical features
- Most are asymptomatic / incidental
- Occasional larger examples may be symptomatic
- Vaginal bleeding, abdominal pain, irregular menses, menorrhagia
- Diffuse variants in immunosuppressed and in HCV / HIV infected patients (Int J Gynecol Cancer 2009;19:242, Ann Pathol 2008;28:308, Int J Gynecol Pathol 2003;22:198)
- May occasionally occur with benign cystic mesothelioma (Histopathology 1996;29:375)
Diagnosis
- By histopathology
Laboratory
- Routine hematological and biochemical parameters are within normal limits
- Occasional anemia and low hemoglobin level because of uterine bleeding
Radiology description
- Magnetic resonance: small solid uterine masses with homogeneous hypointensity on T2 weighted images, and lower enhancement or cystic lesions with inner irregular solid nodules (J Comput Assist Tomogr 2015;39:499)
Prognostic factors
- Benign tumor with excellent prognosis
Case reports
- 26 year old woman with multicentric adenomatoid tumors involving uterus, ovary and appendix (J Obstet Gynaecol Res 2003;29:234)
- 44 year old woman with laparoscopically resected uterine adenomatoid tumor with coexisting endometriosis (J Minim Invasive Gynecol 2011;18:257)
- 44 year old woman with giant cystic adenomatoid tumor of the uterus (J Obstet Gynaecol 2012;32:407)
- 51 year old woman with incidental 3 cm white - tan subserosal nodule (Case of Week #232)
Treatment
- Surgical removal (hysterectomy or rarely simple excision)
Gross description
- Solitary, small (range 0.2 - 3.5 cm, average 2.1 cm), solid nodular, well circumscribed but non encaspulated, ill defined margins, grey - white - yellow rubbery cut surface
- Occasionally grossly inconspicuous
- Rarely diffuse, multifocal, large or predominantly cystic (J Cancer Res Ther 2015;11:967)
- Large multicystic tumors have a honeycomb, spongy pattern / cysts filled with serous fluid
- Exophytic serosal component may rarely be seen
Microscopic (histologic) description
- Organized in vascular-like, gland-like, complex slit-like and cystic branching spaces; also tubules or combination of above
- Less commonly cribriform, solid, anastomosing cords, single cells, focal papillary architecture
- Tubules may contain basophilic secretions
- “Thread like bridging strands” (attenuated cytoplasm that traverse the pseudovascular spaces) (Ann Diagn Pathol 2003;7:273)
- No mitoses; no necrosis; no atypia
- Background: hyperplastic smooth muscle
- Stroma: edematous, inflammatory infiltrate; sometimes lymphoid follicles; lymphocytes or foamy macrophages can be found in the lumina of the tubules
Microscopic (histologic) images
Contributed by Ayse Ayhan, M.D., Ph.D
Various images
Cytology description
- Flattened, cuboidal epithelioid cells: scant, pale, eosinophilic cytoplasm (may contain vacuoles) with hairy basophilic apical surface
- Bland, round nuclei, small nucleoli
- Occasional signet ring-like cells, which are PAS-, mucicarmine-, and may be acidic Alcian Blue+ and colloidal iron+
- No mitotic activity / no cytological atypia
- Occasional nests of squamoid cells
Positive stains
- Cytokeratins: AE1 / AE3, CAM5.2, CK7, CK8, CK18, CK19 (CK5/6 also can be positive)
- Calretinin, D2-40 (Mod Pathol 2009;22:1228)
- WT1 (Int J Gynecol Pathol 2004;23:123)
- HMBE
- Vimentin
- GLUT-1 (cytoplasmic)
- Rarely weak / focal ER and PgR (Appl Immunohistochem Mol Morphol 2012;20:173)
- References: Am J Clin Pathol 1981;76:627; Arch Pathol Lab Med 1985;109:1049; J Pathol 1986;148:327; Int J Gynecol Pathol 1996;15:146; Int J Gynecol Pathol 2002;21:34
Negative stains
Electron microscopy description
- Abundant long slender microvilli, desmosomes, complex intercellular canalicular system, single layer basement membrane (Cancer 1970;25:171)
Molecular / cytogenetics description
- Uniform non random pattern of X chromosome inactivation, consistent with monoclonality (Hum Pathol 2016;48:88)
Differential diagnosis
- Adenocarcinoma (including signet ring cell carcinoma)
- Hemangioma / lymphangioma / peritoneal inclusion cysts
- Leiomyoma
- Lipoleiomyoma
- Well differentiated liposarcoma
Additional references
