of Paratesticular Structures

and Pilar González-Peramato2

Department of Anatomy, Histology and Neuroscience, Universidad Autónoma de Madrid, Madrid, Spain

Department of Pathology, University Hospital La Paz, Universidad Autónoma de Madrid, Madrid, Spain



Testicular neoplasmsTesticular adenomatoid tumorTesticular malignant mesotheliomaCystadenoma of the epididymisAdenocarcinoma of the epididymisEpididymis, adrenal rest tumorEpididymal cystic lymphangioma

Several tumors that have little to do with each other are grouped under this heading, except for the preferred location in the epididymis and tunica vaginalis. Two examples of adenomatoid tumor are included: one of the epididymis, another one an intratesticular tumor; two cystadenomas of the epididymis, one papillary, another one solid; one primary adenocarcinoma of the epididymis; one tumor of adrenal remnants in the epididymis; one malignant mesothelioma of the tunica vaginalis and a cystic lymphangioma of the epididymis. In most of them the architectural pattern is diagnostic, but in others, as the solid pattern epididymis cystadenoma, primary adenocarcinoma of the epididymis and mesothelioma of the tunica vaginalis, the help of immunohistochemistry may be necessary.

8.1 Adenomatoid Tumors

Case 100. Adenomatoid Tumor of the Cauda Epididymis

Clinical case. A 73-year-old patient with a painless paratesticular tumor that has been evolving over several years, until becoming larger than the testicle.

Pathological findings. The tumor is located at the tail of the epididymis and measures 5.1 cm in its maximum diameter. It is firm and well-delimited. It affects neither the testicle nor the spermatic cord. Histologically, it mainly consists of multiple cysts, spherical or elongated, located in a sparse stroma. Focally, it has bundles of smooth muscle cells and lymphoid infiltrates. The cells that line the cysts are flat and have some cytoplasmic vacuoles. Inside the cysts, there are isolated lymphoid cells. Irregularly distributed in the tumor there are clusters of signet-ring cells. Some of these cells have lymphoid cells inside the vacuole. Tumor cells express wide-spectrum cytokeratins, calretinin, D2-40, and WT1.


Fig. 1

Longitudinal section including epididymal testicle and tumor. The tumor is located at the tail of the epididymis; it is well defined and whitish


Fig. 2

The tumor is separated from the lower pole of the testicle. The latter shows a cystic dilation of the rete testis


Fig. 3

Microcystic formations arranged in an arched form. A bundle of smooth muscle cells stand out in the center


Fig. 4

Focal lymphocytic infiltrates between cystic formations


Fig. 5

Group of cystic formations of variable size surrounded by a markedly collagenized stroma. Lymphoid cells are seen inside larger cysts


Fig. 6

Aligned arrangement of cysts separated by connective tissue septa


Fig. 7

The cells that line the cystic spaces have a variable size, from cubic to flat. The larger ones show cytoplasmic vacuoles. The epithelium rests on a fibrous stroma with isolated lymphocytes


Fig. 8

Group of cells reminiscent of adipocytes by the peripheral arrangement of the nuclei and the cytoplasmic vacuole. There are lymphoid cells inside some vacuoles. Between the cells there are thick bundles of cross-sectional collagen fibers


Fig. 9

Strong immunostaining of the epithelial cells of the cystic formations with D2-40


Fig. 10

Immunostaining for calretinin in cells in an area in which signet-ring cells and cystic formations coexist

Comments. There are some unusual findings regarding this tumor, such as the patient’s age, its large size, its microcystic appearance, and the presence of signet-ring cells. Adenomatoid tumors are more frequent between the third and fifth decade of life. The size rarely exceeds that of the testicle. The diffuse microcystic aspect contrasts with the usual clefts with minimal dilatations of the spaces surrounded by epithelial cells observed in most tumors. Signet-ring cells result from the intense cytoplasmic vacuolization that some cells have.

Adenomatoid tumors are benign lesions, which, as in this case, are located at the lower pole of the epididymis. Other locations in decreasing order of frequency are: upper pole of epididymis, albuginea, spermatic cord, and intratesticular. In women, they have been reported in the uterus, the fallopian tube, and the ovary. They can be seen in both sexes in extragenital locations such as the pleura, the heart, the adrenal glands, the mesentery, and the lymph nodes. Adenomatoid tumors of the genital tract, both male and female, are genetically defined by TRAF7 mutation that drives aberrant NF-kB pathway activation.


  1. 1.

    Nistal M, Contreras F, Paniagua R. Adenomatoid tumour of the epididymis: histochemical and ultrastructural study of 2 cases. Br J Urol. 1978;50:121–5.


  2. 2.

    Cordeiro González P, Pérez Fentes DA, Carrera Álvarez JJ, Puñal Pererira A. Adenomatoid paratesticular tumor: report of 5 new cases and literature review. Arch Esp Urol. 2014;67:722–5.


  3. 3.

    Goode B, Joseph NM, Stevers M, Van Ziffle J, Onodera C, Talevich E, Grenert JP, Yeh I, Bastian BC, Phillips JJ, Garg K, Rabban JT, Zaloudek C, Solomon DA. Adenomatoid tumors of the male and female genital tract are defined by TRAF7 mutations that drive aberrant NF-kB pathway activation. Mod Pathol. 2018;31:660–73.


Case 101. Intratesticular Adenomatoid Tumor

Clinical case. A 34-year-old patient presented with an asymptomatic right testicle enlargement. The ultrasonography showed a 2-cm in diameter hypoechoic intratesticular nodule. Testicular tumor markers were within normal limits.

Pathological findings. A large percentage of the testicular parenchyma is occupied by an ovoid, non-encapsulated tumor with a central sclerotic area. It is composed of tubular formations or glandular structures. In the peripheral zone, the tumor infiltrates the testicular interstitium among the seminiferous tubules. The epithelium of the formations is flattened and shows abundant vacuoles. The interstitium contains smooth muscle cells. Necrosis is not observed. There is no mitosis. The cells show immunoexpression for vimentin, calretinin, CK7,WT-1, and D2-40 in the adluminal border.


Fig. 1

Section of testicle and epididymis. An intratesticular tumor with a hyalinized central area is observed


Fig. 2

The delineation between the tumor and the testicular parenchyma is not clear


Fig. 3

Some seminiferous tubules from the periphery of the tumor are included in it. Marked tubular ectasia and intense atrophy of seminiferous tubules by obstructive mechanism


Fig. 4

Tumor cells are arranged to form cords or glandular structures. Most show small cystic dilatations. Between the epithelial formations there is a fibrous stroma, very collagenized with smooth muscle cells


Fig. 5

All epithelial cells have intense immunostaining for vimentin


Fig. 6

Tumor cells revealed with CK7 invade the interstitium and surround the seminiferous tubules


Fig. 7

Atrophic seminiferous tubule surrounded by glandular formations of the adenomatoid tumor (calretinin)


Fig. 8

Intense immunostaining for tumor cell WT-1


Fig. 9

Intense positivity in the apical border of the epithelial cells for D2-40

Comments. Intratesticular adenomatoid tumors are rare: no more than one dozen cases have been reported. They are benign tumors despite the infiltrating peritumoral growth shown by that most of them. The ideal treatment would be enucleation, but in most cases it is not possible due to the difficulties posed by the diagnosis, both with imaging techniques and in an intraoperative biopsy. The histological differential diagnosis includes angiomas, metastases, adenocarcinomas of the rete testis, and mesotheliomas.


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    Alvarez Maestro M, Tur Gonzalez R, Alonso Dorrego JM, Jesus De la Peña Barthel J, Nistal Martin De Serrano M. Adenomatoid tumors of the epididymis and testicle: report of 9 cases and bibliographic review. Arch Esp Urol. 2009;62:137–41.


  2. 2.

    Alexiev BA, Xu LF, Heath JE, Twaddell WS, Phelan MW. Adenomatoid tumor of the testis with intratesticular growth: a case report and review of the literature. Int J Surg Pathol. 2011;19:838–42.


  3. 3.

    Migliorini F, Baldassarre R, Artibani W, Martignoni G, Brunelli M. Rare case of intra-testicular adenomatoid tumour. Arch Ital Urol Androl. 2014;86:44–5.


  4. 4.

    Fabiani A, Maurelli V, Filosa A, Fioretti F, Mammana G. Rare case of intra-testicular adenomatoid tumour. Arch Ital Urol Androl. 2015;87:181–2.


  5. 5.

    Pichler R, Tulchiner G, Steinkohl F, Soleiman A, Horninger W, Heidegger IM, Aigner F. Adenomatoid tumor of the testis mimicking malignant testicular cancer on multiparametric ultrasound. Eur J Med Res. 2018;23:3.


8.2 Malignant Mesothelioma

Case 102. Malignant Mesothelioma of the Tunica Vaginalis

Clinical case. A 62-year-old patient with a history of long-evolution left hydrocele.

Pathological findings. When opening the tunica vaginalis, a yellowish liquid and a large irregular thickening of the parietal leaf with multiple nodular formations penetrating the vaginal cavity is observed. Histologically, besides some nodular formations, the parietal tunica vaginalis shows an infiltration by epithelioid cells that are arranged in nests separated by elongated cells forming bundles. These areas alternate with areas of highly collagenized fibrosis. There are rough and short papillae on the surface. Occasionally, the epithelial cells form small glands. Tumor cells have an ovoid nucleus, a prominent nucleolus, and scarce cytoplasm. In these cells, one or two mitoses are observed per field. The nuclear characteristics of the cells of the fusiform areas are similar. The cytoplasms are wider and eosinophilic. The cells are positive for AE1/AE3, EMA, calretinin, WT1, D2-40, and antimesothelin, and negative for CEA and B72.33.


Fig. 1

Nodular thickening of the parietal leaf of the tunica vaginalis. Tumor nodules penetrate the cavity


Fig. 2

Nodular formations deeply infiltrate the tunica vaginalis and their cells continue with the mesothelial cells of the vaginal lining


Fig. 3

In the areas farthest from the tumor nodules, the mesothelium shows thin papillary proliferations


Fig. 4

The testicular tunica albuginea has fibrosis and an inflammatory infiltrate and a mesothelial lining with marked atypia are observed on the surface


Fig. 5

Papillary proliferation on the surface of the lining of the vaginal cavity


Fig. 6

Patterns of solid and glandular growth. The cells show a spherical nucleus, a large central nucleolus, and an eosinophilic cytoplasm


Fig. 7

A large number of tumor cells express calretinin with the same intensity as normal mesothelium


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Oct 1, 2020 | Posted by in UROLOGY | Comments Off on of Paratesticular Structures
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