A 48-year-old man underwent left testicular mass excision. On gross description, the lesion consisted of a 6mm, whitish, firm, encapsulated fibrous nodule. Representative cross-sections were submitted.

Sections revealed a small well circumscribed nodular lesion which was located in the testicular parenchyma. The lesion was characterized by solid nests and cords of cells set in a densely collagenous stroma (Fig.1-2). The cells had small nuclei and vacuolated cytoplasm (Fig.3). There were no mitotic figures. Immunostains revealed diffuse positivity for vimentin (Fig.4), focal staining for keratin (Fig.5), and scattered positivity for inhibin in those cells (Fig.6).

The differential diagnosis considerations included:

• Adenomatoid tumor
• Metastatic carcinoma
• Sclerosing Sertoli cell tumor

Adenomatoid tumor: Adenomatoid tumors are rare benign neoplasms thought to be of mesothelial origin. It is the most common neoplasm of the epididymis, most patients being in the 3 rd or 4 th decade of life. Although most reported cases arise from the epididymis, rare cases have been reported in the spermatic cord, testicular tunica, ejaculatory ducts, prostate, and suprarenal recess. In female subjects, adenomatoid tumors are commonly found in the uterus and fallopian tubes. It presents clinically as a mass, sometimes associated with pain.

Grossly, it appears as a small, solid, firm, grayish white nodule, occasionally containing small cysts. Under the microscope, the lesion is unencapsulated, and may rarely extend to the adjacent testis. There is a proliferation of cells with vacuolated cytoplasm ranging from cuboidal to flattened, forming solid cords with an epithelial appearance alternating with channels having dilated lumina simulating vascular structures (Table 1). The stroma may contain abundant smooth muscle and elastic fibers; it may also have a reactive desmoplastic quality and be infiltrated by inflammatory cells. Immunohistochemically there is strong reactivity for keratin and EMA (Table 1). Because of the benign nature of this tumor, the treatment of choice is local excision.

Table 1: Adenomatoid tumor: Synopsis

Metastatic carcinoma: Metastases to the testis are most commonly identified in patients with known malignancies ; the most common sites of origin are the prostate (35%), lung (19%), skin (melanoma, 9%), colon (9%), kidney (7%), and elsewhere (20%). In case of differential diagnosis with testicular germ cell tumor, serum alpha-fetoprotein and human chorionic gonadotropin levels are much more likely to be elevated in patients with germ cell tumor. The absence of Intratubular Germ Cell Neoplasia (IGCNU) in the surrounding seminiferous tubules increases the probability of a metastatic tumor, as do Epithelial Membrane Antigen (EMA) positivity and Placental Alkaline Phosphatase (PLAP) negativity. Other immunohistochemical studies may prove useful.

Sclerosing Sertoli cell tumor: This is a group of rare tumors of the testis derived from the interstitial cells. Sertoli cells, together with the Leydig cells comprise the majority of these cells. These tumors may present with hormonal manifestations. Sertoli cell tumors account for about 1% of all primary testicular tumors. It can occur at any age but is most common in middle age. They have been subtyped as classical Sertoli cell tumor, large cell calcifying Sertoli cell tumor, sclerosing Sertoli cell tumor and Sertoli cell tumors NOS.

Sclerosing Sertoli cell tumor was first described in 1991 by Zukerberg et al. who reported 10 cases. All patients with sclerosing Sertoli cell tumor present with a testicular mass without associated hormonal symptoms. Grossly, the lesion is usually small (0.4-1.5 cm in diameter) and consists of solid, white to yellow-tan nodules. Microscopically, it is composed of cords, solid or hollow tubules, and nests of Sertoli cells set in a densely collagenous stroma. The nuclei vary from large to small, and the cytoplasm is pale and sometimes vacuolated. Vimentin and inhibin are present in the neoplastic cells. Pancytokeratin may be focally positive. All the reported cases had a benign outcome.

Sclerosing Sertoli cell tumor.

Key Features:

• Occur in men with a mean age of 30 years, range 18 to 80 years, not associated with hormone production
• Well circumscribed, small (0.4 to 1.5 cm in diameter), yellow-white-tan
• Microscopically
  • Small solid cords, anastomosing tubules and thin cords of Sertoli cells in a prominent fibrous sclerosing stroma with thick collagenous bands
  • Bland nuclei
  • No/rare atypia and mitotic figures
  • Fibrous stroma may entrap non-neoplastic tubules
• Immunohistochemistry
  • Vimentin +++
  • AE1/AE3 cytokeratin +
  • Inhibin +
• • adenomatoid tumor (usually paratesticular, no prominent fibrosis, cytokeratin strongly positive, and inhibin negative)
  • metastatic carcinoma (marked atypia)

Follow-up: To date, there are no reports of recurrence or metastases

1. Abbas F, Bashir NW, Hussainy AS. Sclerosing Sertoli cell tumor of the testis. J Coll Physicians Surg Pak. 2005;15(7):437-8.
2. Giglio M, Medica M, De Rose AF, et al. Testicular sertoli cell tumours and relative sub-types. Analysis of clinical and prognostic features. Urol Int. 2003;70(3):205-10.
3. Reale D, Pascale M, Vitullo G, et al. [Sclerosing Sertoli cell tumor of the testis. Report of a case and review of the literature] Minerva Urol Nefrol. 2002;54(3):179-82.
4. Zukerberg LR, Young RH, Scully RE. Sclerosing Sertoli cell tumor of the testis. A report of 10 cases. Am J Surg Pathol. 1991;15(9):829-34.