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Adenomatoid Tumor

Last updated April 26, 2018

Approved by: Krish Tangella MD, MBA, FCAP


Intermediate micrographic pathology image showing a Adenomatoid tumor.

What are the other Names for this Condition? (Also known as/Synonyms)

  • Benign Adenomatoid Mesothelioma
  • Benign Mesothelial Adenomatoid Tumor
  • Benign Mesothelioma of Adenomatoid Type

What is Adenomatoid Tumor? (Definition/Background Information)

  • Adenomatoid Tumor resembles an adenoma and arises from the mesoderm (epithelium that lines body cavities; also called mesothelium). Adenoma is benign (non-cancerous) overgrowth of tissue of gland-like structure, or of glandular origin
  • Adenomatoid Tumors commonly arise in the genital tract:
    • In women, they are commonly found in the myometrium (middle layer of the uterus)
    • Adenomatoid Tumors are the most common benign tumor of the fallopian tubes
    • It also occurs in the uterine wall (beneath the serosa and closer to the cornua) and within and outside the ovaries       In men, they represent 30% of all tumors and 60% of benign tumors of all paratesticular (structures alongside the testis) tumors
    • It is the most common tumor of the epididymis (most commonly upper pole, tail) and spermatic cord (especially funiculus)
    • It may also involve ejaculatory duct and tunica vaginalis part of testis
  • Adenomatoid Tumors rarely involve sites outside the genital tract. When they occur outside the genital region, they may involve the following sites:
    • Adenomatoid Tumor of Peritoneum (smooth transparent serous membrane lining the internal abdominal cavity)
    • Adenomatoid Tumor of Pleura (the membrane lining the lungs)        
    • Adenomatoid Tumor of Adrenal Gland (it may resemble another tumor of adrenal gland called lymphangioma)
    • Adenomatoid Tumor of Appendix
    • Adenomatoid Tumor of Heart
    • Adenomatoid Tumor of Hernia sac
    • Adenomatoid Tumor of Intestinal Mesentery, Omentum, Mesocolon
    • Adenomatoid Tumor of Liver
    • Adenomatoid Tumor of Lymph node
    • Adenomatoid Tumor of Mediastinum
    • Adenomatoid Tumor of Pancreas
    • Adenomatoid Tumor of Umbilicus
    • Adenomatoid Tumor of Prostate
    • Adenomatoid Tumor of Suprarenal Recess
    • Adenomatoid Odontogenic Tumor (adenoameloblastoma) arising from odotontogenic epithelium of dental lamina of maxillary or mandibular bone
  • The diagnoses of Adenomatoid Tumors are confirmed through a tissue biopsy
  • The treatment is complete surgical removal of the tumor
  • The prognosis of Adenomatoid tumor is excellent, with suitable treatment
  • Currently, no known methods exist to prevent Adenomatoid Tumor occurrence 

Who gets Adenomatoid Tumor? (Age and Sex Distribution)

  • Both men and women are at risk for Adenomatoid Tumors
  • In women, they are most mostly found ‘incidentally’, during surgical tissue removal for other reasons, such as fibroids, uterine adenomyosis, uterine endometrial cancer, endometriosis, ovarian tumor, ovarian abscess, and tubal ligation procedure.
  • Fallopian tube tumors have been reported mostly in middle-aged to older women
  • Adenomatoid Paratesticular Tumors are seen in men between their 3rd and 5th decades (21-50 years)
  • These tumors are observed in men and women worldwide. All races and ethnic groups can be affected

What are the Risk Factors for Adenomatoid Tumor? (Predisposing Factors)

  • No clear-cut risk factors for Adenomatoid Tumor have been currently established

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others. 

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider. 

What are the Causes of Adenomatoid Tumor? (Etiology)

  • The cause for development of Adenomatoid Tumor is unknown
  • Scientists are yet to ascertain if Adenomatoid Tumors are neoplastic or hyperplastic
  • Some believe that trauma or inflammation may be an inciting factor for causation of these tumors

What are the Signs and Symptoms of Adenomatoid Tumor?

The signs and symptoms associated with Adenomatoid Tumor include:

  • In women, Adenomatoid Tumors are clinically asymptomatic (typically) and usually found incidentally. It may cause symptoms, such as menstrual irregularities or lump in the abdomen and pelvis
  • In men, Adenomatoid Tumors are usually asymptomatic. In some cases, it may be present as unilateral mass with or without pain.

How is Adenomatoid Tumor Diagnosed?

The following procedures may be used to diagnose Adenomatoid Tumor:

  • Evaluation of the individual’s medical history and physical examination
  • Adenomatoid Tumor is often found incidentally during surgical procedures that are performed for other reasons, or during physical examination of the genital tract
  • An ultrasound scan may suggest to the physician a diagnosis of male genital tract tumors, such as an Adenomatoid Tumor. Radiology studies may show this tumor to be a solid, extra-testicular mass, with variable echogenicity. MRI studies may also be useful for diagnosing male paratesticular genital tract lesions
  • During the removal of Adenomatoid Tumor of Testis, a frozen section maybe employed to rule out more serious cancer, which allows for testicle sparing surgery
  • Tissue biopsy of tumor: A tissue biopsy is performed and sent to a laboratory for a pathological examination. A pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis. Examination of the biopsy under a microscope by a pathologist is considered to be gold-standard in arriving at a conclusive diagnosis
  • Sometimes, the pathologist may perform special studies, which may include immunohistochemical stains, histochemical stains, molecular testing, and very rarely electron microscopic studies
  • Differential diagnosis, to eliminate other tumor types are often considered, before arriving at a definitive diagnosis
  • Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Adenomatoid Tumor?

Paratesticular adenomatoid may be complicated by pain. 

How is Adenomatoid Tumor Treated?

Treatment measures for Adenomatoid Tumor include the following:

  • Typically, Adenomatoid Tumors are surgically removed, even though they are benign neoplasms. A surgical resection of the Adenomatoid Tumor results in a cure
  • In the case of paratesticular tumor, enucleation (complete removal without cutting through the tumor) is performed, without the removal of the testis

How can Adenomatoid Tumor be Prevented?

Current medical research has not established a way of preventing Adenomatoid Tumor formation. 

What is the Prognosis of Adenomatoid Tumor? (Outcomes/Resolutions)

  • The prognosis of Adenomatoid Tumors is very good, even if they infiltrate (extend into) adjacent structures. Even if there is local infiltration, they do not metastasize (spread to distant parts of the body). The tumors do not progress or recur following their surgical removal
  • As with any tumor, it is important to have follow-up appointments with a physician, to monitor for any returning tumors

Additional and Relevant Useful Information for Adenomatoid Tumor:

  • A tumor is an abnormal growth of tissue arising due to uncontrolled and rapid multiplication of cells that serve no function. They are also called neoplasms. Tumors may be benign or malignant (of cancer type)
  • The biopsy specimens of Adenomatoid Tumors are studied using Hematoxylin and Eosin staining. The pathologist may use special studies such as special stains. Special stains (markers used on biopsy samples may include:
    • Calretinin
    • D2-40        
    • CKAE1/CAM5.2
    • WT-1
  • These stains help to differentiate Adenomatoid Tumors from other benign or cancerous lesions.

What are some Useful Resources for Additional Information?

References and Information Sources used for the Article:

Helpful Peer-Reviewed Medical Articles:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Oct. 3, 2015
Last updated: April 26, 2018