Final Diagnosis and Discussion:
The images show nodular proliferation of seminiferous tubules in a background of benign,
atrophic testicular parenchyma (Figure 1A & 1B). These prepubertal sized tubules are
lined by a pseudostratified epithelium composed of immature Sertoli cells with hyperchromatic
nuclei and scant cytoplasm. Tubular lumina are inconspicuous, however some tubules
show luminal globular hyaline deposits with foci of calcification (Figures 2A & 2B).
The interstitium is scant with focal collection of Leydig cells (Figure 3, black arrows).
These features qualify for a diagnosis of Sertoli cell nodule.
Sertoli cell nodule (also known as Sertoli cell hyperplasia, tubular dysgenesis, hypoplastic zones or Pick adenoma) is a primary testicular lesion consisting of non-neoplastic proliferation of immature Sertoli cells within seminiferous tubules and is included in the spectrum of testicular dysgenesis syndrome. This entity has been identified in adult cryptorchid testes (60%), normal testes (22%), occasionally in men with infertility and in the parenchyma surrounding germ cell tumors. Usually, it is an asymptomatic and incidental finding. Size can range from microscopic to up to 10 mm, which is termed macroscopic Sertoli cell nodule. Macroscopic Sertoli cell nodule can present clinically as a palpable mass or firmness, with associated testicular pain or as a visible mass on ultrasound. It is important to be knowledgeable about this entity as there is potential for diagnostic misinterpretation that may lead to unnecessary treatment. After histologic diagnosis, no further intervention is necessary.
Although the etiology is unknown, it represents seminiferous tubules that are unable
to undergo pubertal development despite the same hormonal stimuli as adjacent normal
tubules. The proliferation of Sertoli cells has been identified in various settings
which could help explain the pathophysiology of this entity. In the setting of sexually
immature testes, the Sertoli cells are mitotically active while their numbers remain
stable in adult, mature testes. In the setting of developmental arrest of seminiferous
tubules, there is lack of lengthening of the tubules that prevents the widespread
distribution of Sertoli cells. In cryptorchid testes, the presence of immature Sertoli
cells could be explain by different factors including increased temperature of the
undescended testis, association with congenital lesions and hormonal influences.
Macroscopically, the testicular cut surface is unremarkable, at times single or multiple,
well-circumscribed, white-tan to yellow-tan, firm to gelatinous nodules may be obvious.
Histologically, these circumscribed, unencapsulated nodules comprise of prepubertal
sized, variably shaped seminiferous tubules, varying from round to oval to anastomotic.
These tubules are lined by columnar to pseudostratified lining of Sertoli cells possessing
round to ovoid hyperchromatic nuclei, with one or more peripherally located nucleoli,
and scant cytoplasm. They are devoid of lumina but may contain globular hyaline material
deposits due to invagination of the excess basal lamina like material produced by
the Sertoli cells. A ring like manner of arrangement of Sertoli cells can be observed
around the hyaline material, which occasionally may undergo calcification. Isolated
spermatogonia may be present. The interstitium varies from scant to well collagenized
and Leydig cells are usually absent or low in numbers.
Ancillary studies are not necessary for diagnosis. On immunohistochemistry, immature Sertoli cells can be highlighted by Vimentin, D2-40, CK8/18, calretinin and inhibin; occasional spermatogonia by NY-ESO-1 and TSPY; and the basement membrane material by PAS. The hyaline material appears as compact multilamellar matrix o, Sertoli,n electron microscopy.
Differential Diagnosis
Sertoli cell tumor not otherwise specified
Usually, nodules are over 1 cm in diameter. The cells are larger with vesicular nuclei
and prominent nucleoli arranged in cords and tubules, with absence of basal membrane
thickening and germ cells. Nuclear atypia and mitotic activity may be observed. While
in contrast Sertoli cell nodule possesses uniform and cytologically bland immature
Sertoli cells, with associated basal membrane thickening and rare germ cells.
Intratubular large hyalinizing Sertoli cell neoplasia
Multiple nodules composed of large non-anastomotic tubules. Thickening of basal membranes
and intratubular globular membrane deposits is observed similar to Sertoli cell nodule.
However, Sertoli cells have a higher degree of maturation showing vesicular nuclei
with central nucleoli, abundant eosinophilic cytoplasm, and an accompanying absence
of germ cells. Intratubular large hyalinizing Sertoli cell neoplasia is associated
with Peutz-Jeghers syndrome.
Tubular hamartoma
Tubular hamartoma is almost exclusively seen in patients with androgen insensitivity
syndrome (AIS). Nodules are usually larger in diameter, multifocal and composed of
solid tubules of immature Sertoli cells. Sertoli cells show spherical nuclei and lack
pseudostratification. Globular basement membrane deposits are absent. Tubular hamartoma
has a densely cellular interstitium with fusiform cells and numerous Leydig cells.
Of note, Sertoli cell adenomas are also seen in AIS patients and can have almost
identical histologic findings as hamartomatous lesions but lack interstitial Leydig
cells. Therefore, tubular hamartoma and Sertoli cell adenoma are sometimes grouped
together when discussing differential diagnoses for Sertoli cell nodules.
References
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Sertoli cell lesions.” Journal of clinical pathology vol. 59,11 (2006): 1223-5. doi:10.1136/jcp.2005.035253
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doi:10.1002/aja.1001000205
4. Govender, D et al. “Sertoli cell nodules in the undescended testis: a histochemical,
immunohistochemical, and ultrastructural study of hyaline deposits.” Journal of clinical
pathology vol. 57,8 (2004): 802-6. doi:10.1136/jcp.2004.015982
5. Nistal, M et al. “Hyperplasia and the immature appearance of Sertoli cells in primary
testicular disorders.” Human pathology vol. 13,1 (1982): 3-12. doi:10.1016/s0046-8177(82)80132-9
6. Vallangeon, Bethany D et al. “Macroscopic sertoli cell nodule: a study of 6 cases
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34,12 (2010): 1874-80. doi:10.1097/PAS.0b013e3181fcab70
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Board type review questions:
1. Which stain can highlight germ cells present in Sertoli cell nodules?
a. CK8/18
b. TSPY
c. PAS
d. D2-40
2. The following statements regarding Sertoli cell nodule is true:
a. Sertoli cell nodules are commonly found in cryptorchid testes
b. Approximately 50% progress to Sertoli cell tumor
c. Nodular proliferation is composed of tubules lined by mature Sertoli cells
d. Nuclear atypia and mitotic activity are variably present