Adenomatoid tumors are rare and

benign Malignancy () is the tendency of a medical condition to become progressively worse; the term is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous benign tumor, ''benign'' tumor in that a malig ...

mesothelial The mesothelium is a membrane composed of simple squamous epithelial cells of mesodermal origin, which forms the lining of several body cavities: the pleura (pleural cavity around the lungs), peritoneum (abdominopelvic cavity including the mesent ...

tumor A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

s, which arise from the lining of organs. It mainly presents in the genital tract, in regions such as the

testis A testicle or testis ( testes) is the gonad in all male bilaterians, including humans, and is Homology (biology), homologous to the ovary in females. Its primary functions are the production of sperm and the secretion of Androgen, androgens, p ...

and

epididymis The epididymis (; : epididymides or ) is an elongated tubular genital organ attached to the posterior side of each one of the two male reproductive glands, the testicles. It is a single, narrow, tightly coiled tube in adult humans, in length; ...

. Because of this, researchers had a difficult time concluding that type of tumor has a mesothelial origin. Immunohistochemistry staining of tumor samples show that it is indeed positive for mesothelial-markers (calretinin, WT1, and CK6). It is the most common extratesticular neoplasm after lipoma, and accounts for 30% of these masses. On the other hand, adenomatoid tumors are the most common tumors of testicular adnexa. Although they are more common to be found in the paratesticular region they are sometimes found in the intratesticular region. It also has been found in other organs such as the

pancreas The pancreas (plural pancreases, or pancreata) is an Organ (anatomy), organ of the Digestion, digestive system and endocrine system of vertebrates. In humans, it is located in the abdominal cavity, abdomen behind the stomach and functions as a ...

liver The liver is a major metabolic organ (anatomy), organ exclusively found in vertebrates, which performs many essential biological Function (biology), functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of var ...

, mesocolon, and

adrenal gland The adrenal glands (also known as suprarenal glands) are endocrine glands that produce a variety of hormones including adrenaline and the steroids aldosterone and cortisol. They are found above the kidneys. Each gland has an outer adrenal corte ...

s. In the female, it has been found in the body of the

uterus The uterus (from Latin ''uterus'', : uteri or uteruses) or womb () is the hollow organ, organ in the reproductive system of most female mammals, including humans, that accommodates the embryonic development, embryonic and prenatal development, f ...

and the

fallopian tube The fallopian tubes, also known as uterine tubes, oviducts or salpinges (: salpinx), are paired tubular sex organs in the human female body that stretch from the Ovary, ovaries to the uterus. The fallopian tubes are part of the female reproduct ...

. Most adenomatoid tumors do not cause much pain and can go unnoticed for a long time. Of course, there are a few exceptions to this absence of pain. An example of this is when adenomatoid tumors grow too close to testicular adnexal structures. Tumors of this kind are usually found to be asymptomatic and easily treatable.

Pathology

While adenomatoid tumors are present in both the various body areas of males and females, one study discovered that these tumors were more likely to occur in Caucasian males. Adenomatoid tumors can be found in a widespread age of people ranging from 18 to 79 years old. Most of these tumors are not spotted until about the 30s. This asymptomatic nature is because a majority of adenomatoid tumors grow silently and are sometimes dormant without causing any pain. This is what contributes to the difficulty of catching adenomatoid tumors. These benign tumors can grow up to 5.0 centimeters (most of them range around to 2.0 cm). Although adenomatoid tumors are not known to infiltrate surrounding tissues, it is possible that there are multiple adenomatoid tumors in the same area. File:Histopathology of an adenomatoid tumor of the fallopian tube, low magnification.jpg, An adenomatoid tumor of the fallopian tube, low magnification, displaying infiltrative-like borders. File:Histopathology of an adenomatoid tumor of the fallopian tube, intermediate magnification.jpg, High magnification of the same case, showing the typical Topic Completed: 1 September 2013. Minor changes: 13 December 2019 features of tubular spaces of varying size composed of flattened cells resembling endothelium.

Ancillary Studies

Immunohistochemistry

Given their mesothelial origin, the cells lining the spaces are positive for cytokeratins,

WT1 Wilms tumor protein (WT33) is a protein that in humans is encoded by the ''WT1'' gene on chromosome 11p. Function This gene encodes a transcription factor that contains four zinc finger motifs at the C-terminus and a proline / glutamine-rich ...

, D2-40, and

calretinin Calretinin, also known as calbindin 2 (formerly 29 kDa calbindin), is a calcium-binding protein involved in calcium signaling. In humans, the calretinin protein is encoded by the ''CALB2'' gene. Function This gene encodes an intracellular ...

. They are negative for MOC31, BerEP4, and vascular markers (CD31 or CD34).

BAP1 BRCA1 associated protein-1 (ubiquitin carboxy-terminal hydrolase) is a deubiquitinating enzyme that in humans is encoded by the ''BAP1'' gene. ''BAP1'' encodes an 80.4 kDa nuclear-localizing protein with a ubiquitin carboxy-terminal hydrolase ( ...

expression is retained. L1 cell adhesion molecule (L1CAM), a marker of NF-kB pathway activation, has been shown to be expressed in adenomatoid tumors (and negative in other benign mesothelial tissues and mesothelioma).

Molecular analysis

Adenomatoid tumors of the female and male genital tract are characterized by somatic missense mutations in the TRAF7 gene, which leads to aberrant NF-kB pathway activation. Unlike some malignant mesotheliomas, adenomatoid tumors do not harbor

CDKN2A ''CDKN2A'', also known as cyclin-dependent kinase inhibitor 2A, is a gene which in humans is located at chromosome 9, band p21.3. It is ubiquitously expressed in many tissues and cell types. The gene codes for two proteins, including the INK4 f ...

deleterious mutations.

Imaging

In order to see adenomatoid tumors multiple imaging modalities are used. These tumors appear to be small, solid, and circumscribed with a color that usually ranges from white to tan.

Ultrasound Ultrasound is sound with frequency, frequencies greater than 20 Hertz, kilohertz. This frequency is the approximate upper audible hearing range, limit of human hearing in healthy young adults. The physical principles of acoustic waves apply ...

MRI Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and rad ...

, and CT scans are all used to identify whether a patient has adenomatoid tumors. The shape, location, and activity of the tumor are all important information to attain. Each imaging modality has its own strengths and weaknesses. Dynamic contrast enhanced MRI can differentiate tumors from disorders in the testicular region. Misdiagnosing something can sometimes cause more damage then doing nothing. One weakness of adenomatoid tumor ultrasound imaging is that it is only possible if the tumor is

hyperechoic Echogenicity (sometimes as echogenecity) or echogeneity is the ability to bounce an echo, e.g. return the signal in medical ultrasound examinations. In other words, echogenicity is higher when the surface bouncing the sound echo reflects increase ...

. Ultrasonically can help identify if it fits this category or not. This specific characteristic in adenomatoid tumors is variable and can determine whether or not ultrasound is the right technique for the job. Having other options available to identify the tumor helps fill in the gap when ultrasound is not possible. MRI and CT imaging are usually helpful when scanning the adrenal gland for tumors.

Treatment

If located in the testes region, removal of the tumor must be handled with great care to prevent damage to testosterone production and keep the patient fertile. If removal of the tumor is necessary then an excision biopsy is usually done on the patient. Though this can be used as both a diagnostic and removal procedure, it has proven to be effective. Successful procedures results in a tumor free area that is not prone recur. When used as a diagnosis tool, the excision biopsy can collect a tissue sample from the tumor. Through

histological Histology, also known as microscopic anatomy or microanatomy, is the branch of biology that studies the microscopic anatomy of biological tissue (biology), tissues. Histology is the microscopic counterpart to gross anatomy, which looks at large ...

evaluation the lesion can be categorized in the patients.

Additional images

References

External links

{{Soft tissue tumors and sarcomas Benign neoplasms Connective and soft tissue neoplasms