Testicular Adenomatoid Tumor Pathology
- Author: Fabio R Tavora, MD, PhD; Chief Editor: Liang Cheng, MD more...
An adenomatoid tumor is a benign neoplasm of mesothelial origin that can be found in both female and male genital tracts, but it is more commonly found in the male adnexa, where it is the most common benign neoplasm.
Adenomatoid tumors represent 30% of the tumors of the testicular adnexa and 60% of benign tumors of these structures. Beccia et al studied 314 epididymis tumors, of which 75% were benign and 73% of those were diagnosed as adenomatoid tumors, followed by leiomyomas (11%), and papillary cystoadenomas of the epididymis (9%). These tumors are commonly incidental findings, most often seen in patients in the third through fifth decades, although one case in a 70-year-old patient has been reported and another in boy younger than 5 years.
The mesothelial origin of adenomatoid tumors is currently accepted based on ultrastructural and immunohistochemical analyses.[4, 5, 6, 7, 8] It was first suggested by Evans in 1943 but refuted by Golden and Ash, who proposed the term "adenomatoid tumor" that is now accepted and in widespread use.
Adenomatoid tumors are most commonly located in the male genital tract, in the lower pole of the epididymis, followed by the tunica vaginalis and spermatic cord. Extragenital tumors have also been described in places such as the adrenal gland,[12, 13] lymph nodes, mediastinum, heart, pancreas, and pleura. The involvement of the mesocolon and omentum has also been reported.[18, 19]
Clinical Features and Imaging
These tumors usually present clinically as a solid, hyperechoic, well-circumscribed mass, between 1 and 5 cm, although a 6-cm adenomatoid tumor has been reported. Adenomatoid tumors typically have no distinct growth pattern. In the epididymis and testicle, these lesions can cause pain and demonstrate a palpable mass. Dell'atti reports a case diagnosed with testicular ultrasound.
Grossly, adenomatoid tumors appear as small, solid, firm, grayish white nodules; they are usually well circumscribed and occasionally contain small cysts.
Microscopically, the adenomatoid lesion is unencapsulated, and on rare occasions, it may extend to the testicular parenchyma (most often tumors of the upper pole). There is a proliferation of cells ranging from cuboidal to flattened, which form solid cords with an epithelial appearance alternating with tubular and angiomatoid spaces (see the following images). These cells have weakly acidophil and markedly vacuolated cytoplasm, without prominent nucleoli and little to no mitotic activity. The surrounding stroma is fibrous, sometimes hyalinized, and may contain abundant smooth muscle and elastic fibers, with inner lymphoid aggregates.
The 3 patterns of adenomatoid tumors recognized by Taxy et al are plexiform, tubular, and canalicular, with most cases showing a mixture of multiple patterns. Tiltman subsequently used the same classification for tumors of the female genital tract. Quigley and Hart described 4 other histologic patterns that were similar to the ones described by Taxy :
Adenomatoid (tubular): Characterized by glandular structures, irregularly lined by cuboidal cells, some of which have vacuolated cytoplasm, resembling signet ring cells (see the images below)
Angiomatoid (canalicular): Consist of wide pseudovascular spaces, composed of flattened cells, scant cytoplasm, with an endothelial appearance
Solid (plexiform): Formed by solid cords of cells with abundant, eosinophilic cytoplasm, with an epithelial-like appearance
Cystic (mixed): A rare form, characterized by big, cystic cavities separated by fibrous septa, and lined by flattened to cuboidal cells
Other histologic findings include tumors with infarcted areas, abundant fibroblastic and myofibroblastic proliferation, and also increased mitotic activity, which can occasionally make the diagnosis difficult.
The mesothelial origin of adenomatoid tumors is proved by its positivity for calretinin and epithelial markers, such as AE1AE3, epithelial membrane antigen (EMA), Cam5.2, CK5/6, and CK7 (see the following images). The latter 2 markers (CK5/6, CK7) may be only focally positive. Endothelial markers such as CD31 and CD34 are negative. In difficult cases, in which the differential diagnosis is metastatic adenocarcinoma, a panel to include markers that are positive in carcinoma and not in mesothelial proliferation may include carcinoembryonic antigen (CEA), factor VIII-related antigen, HBME-1,MOC31, BER-EP4, B72.3, and CD15.
Adenomatoid tumors are negative for germ cell tumor markers such as OCT3/4, Nanog, Sox-2, alpha-fetoprotein (AFP), placental alkaline phosphatase (PLAP), CD117, and CD30, in the rare occasions in which the hematoxylin and eosin (H&E) evaluation alone does not readily render a diagnosis of the tumor.
No specific genetic abnormalities have been found in adenomatoid tumors.
Tumor Spread and Staging
Adenomatoid tumors are uniformly benign neoplasms. In selected cases, these tumors can encroach the testicular adnexal structures and mimic a malignant proliferation on imaging. Frozen section diagnosis can readily establish the diagnosis in typical cases and allow for testicle-sparing surgery.[23, 24]
Papillary Cystadenoma of the Epididymis
Beccia DJ, Krane RJ, Olsson CA. Clinical management of non-testicular intrascrotal tumors. J Urol. 1976 Oct. 116(4):476-9. [Medline].
Morote J, Rabella A, Benasco C. [Adenomatoid tumor of the epididymis] [Spanish]. Arch Esp Urol. 1984 Jan-Feb. 37(1):61-4. [Medline].
Liu W, Wu RD, Yu QH. Adenomatoid tumor of the testis in a child. J Pediatr Surg. 2011 Oct. 46(10):E15-7. [Medline].
Ferenczy A, Fenoglio J, Richart RM. Observations on benign mesothelioma of the genital tract (adenomatoid tumor). A comparative ultrastructural study. Cancer. 1972 Jul. 30(1):244-60. [Medline].
Taxy JB, Battifora H, Oyasu R. Adenomatoid tumors: a light microscopic, histochemical, and ultrastructural study. Cancer. 1974 Aug. 34(2):306-16. [Medline].
Marcus JB, Lynn JA. Ultrastructural comparison of an adenomatoid tumor, lymphangioma, hemangioma, and mesothelioma. Cancer. 1970 Jan. 25(1):171-5. [Medline].
Manson AL. Adenomatoid tumor of testicular tunica albuginea mimicking testicular carcinoma. J Urol. 1988 Apr. 139(4):819-20. [Medline].
Delahunt B, Eble JN, King D, Bethwaite PB, Nacey JN, Thornton A. Immunohistochemical evidence for mesothelial origin of paratesticular adenomatoid tumour. Histopathology. 2000 Feb. 36(2):109-15. [Medline].
Evans N. Mesothelioma of the epididymis and tunica vaginalis. J Urol. 1943. 50:249-54.
Canedo-Patzi AM, Leon-Bojorge B, de Ortiz-Hidalgo C. [Adenomatoid tumor of the genital tract. Clinical, pathological and immunohistochemical study in 9 cases] [Spanish]. Gac Med Mex. 2006 Jan-Feb. 142(1):59-66. [Medline].
Isotalo PA, Keeney GL, Sebo TJ, Riehle DL, Cheville JC. Adenomatoid tumor of the adrenal gland: a clinicopathologic study of five cases and review of the literature. Am J Surg Pathol. 2003 Jul. 27(7):969-77. [Medline].
Garg K, Lee P, Ro JY, Qu Z, Troncoso P, Ayala AG. Adenomatoid tumor of the adrenal gland: a clinicopathologic study of 3 cases. Ann Diagn Pathol. 2005 Feb. 9(1):11-5. [Medline].
Isotalo PA, Nascimento AG, Trastek VF, Wold LE, Cheville JC. Extragenital adenomatoid tumor of a mediastinal lymph node. Mayo Clin Proc. 2003 Mar. 78(3):350-4. [Medline].
Plaza JA, Dominguez F, Suster S. Cystic adenomatoid tumor of the mediastinum. Am J Surg Pathol. 2004 Jan. 28(1):132-8. [Medline].
Overstreet K, Wixom C, Shabaik A, Bouvet M, Herndier B. Adenomatoid tumor of the pancreas: a case report with comparison of histology and aspiration cytology. Mod Pathol. 2003 Jun. 16(6):613-7. [Medline].
Minato H, Nojima T, Kurose N, Kinoshita E. Adenomatoid tumor of the pleura. Pathol Int. 2009 Aug. 59(8):567-71. [Medline].
Yeh CJ, Chuang WY, Chou HH, Jung SM, Hsueh S. Multiple extragenital adenomatoid tumors in the mesocolon and omentum. APMIS. 2008 Nov. 116(11):1016-9. [Medline].
Hanrahan JB. A combined papillary mesothelioma and adenomatoid tumor of the omentum: report of a case. Cancer. 1963 Nov. 16:1497-500. [Medline].
Dell'atti L. Ultrasound diagnosis of unusual extratesticular mass: case report and review of the literature. Arch Ital Urol Androl. 2013 Apr 19. 85(1):41-3. [Medline].
Tiltman AJ. Adenomatoid tumours of the uterus. Histopathology. 1980 Jul. 4(4):437-43. [Medline].
Quigley JC, Hart WR. Adenomatoid tumors of the uterus. Am J Clin Pathol. 1981 Nov. 76(5):627-35. [Medline].
Fabiani A, Filosa A, Pieramici T, Mammana G. Testicular Nodules Suspected for Malignancy. Does the Pathologist Make the Difference for Organ-Sparing Surgery? . Anal Quant Cytopathol Histpathol. 2015 Jun. 37 (3):147-52. [Medline].
Tuygun C, Ozturk U, Goktug HN, Zengin K, Sener NC, Bakirtas H. Evaluation of frozen section results in patients who have suspected testicular masses: a preliminary report. Urol J. 2014 Mar 3. 11 (1):1253-7. [Medline].