Testicular Fibrothecoma: A Morphologic and Immunohistochemical Study of 16 Cases

Contemporary Updates on Sex Cord-stromal Tumors of the Testis

Testicular sex cord-stromal tumors (TSCSTs) are relatively rare, representing ~5% of testicular neoplasms overall. Historically, TSCSTs have been classified into 3 major entities: Leydig cell tumor, Sertoli cell tumor, and granulosa cell tumor. In recent years, immunophenotypic and molecular analyses have led to a more detailed understanding of the biological and genomic features of these neoplasms, resulting in the description of new entities, some of which have been included in the latest WHO classification. This review summarizes novel histopathologic, clinical, and molecular findings that may lead to a reappraisal of established concepts and help improve the diagnosis and clinical management of TSCSTs in the coming years.

[Fundamentals in the pathology of testicular tumours]

The most common group of testicular tumours comprises germ cell tumours. Other primary testicular tumours are rare, but it is important to be aware of the wide variety of other, much rarer testicular tumours for the differential diagnosis. These tumours include sex cord stromal tumours and testicular adnexal tumours, which must be distinguished from metastases or somatic-type malignancies in germ cell tumours. Immunohistochemical markers and molecular alterations can help to correctly diagnose these tumours.

An update on diagnostic tissue-based biomarkers in testicular tumors

Testicular cancer is rare overall but comprises the most common solid malignancy diagnosed in young men aged ∼20-40 years. Most testicular neoplasms generally fall into 2 broad categories: germ cell tumors (GCTs; ∼95%) and sex cord-stromal tumors (SCSTs ∼5%). Given the relative rarity of these tumors, diagnostic biomarkers are highly relevant for their diagnosis. Over the past several decades, diagnostic biomarkers have improved dramatically through targeted immunohistochemical and molecular characterization. Despite these recent advances, most markers are not perfectly sensitive or entirely specific. Therefore, they need to be used in combination and interpreted in context. In this review, we summarize tissue-based biomarkers relevant to the pathologist, with a focus on practical diagnostic issues that relate to testicular GCT and SCST.

Testicular fibroma: A case report and literature review

Sex cord-stromal tumors are the second most common testicular tumors after germ cell tumors. They account for about 2%–5% of adult testicular tumors. Most of these tumors are benign. The most common sex cord-stromal tumor is Leydig cell tumor. In contrast, testicular fibroma is a very rare type of sex cord-stromal tumors. Histologically, testicular fibromas resemble their ovarian counterparts; however, they are much less common than ovarian fibromas. To the best of our knowledge, <50 cases of testicular fibromas are reported in the English literature. Herein, we report a rare case of testicular fibroma with acellular collagen plaque in a 51-year-old male presenting as a painless testicular mass.

Testicular Tumors: A Contemporary Update on Morphologic, Immunohistochemical and Molecular Features

Testicular tumors are incredibly diverse and one of the most challenging areas in surgical pathology. Because of the rarity and overlapping features with numerous entities occurring in the testis and paratestis, these tumors pose a diagnostic challenge even to the most experienced general pathologists. In 2016, the latest "World Health Organization (WHO) classification of testicular tumors" was released, which incorporated several updates to the previous 2004 classification system. These updates involved several entities, including germ cell tumors, sex cord-stromal tumors, tumors containing both germ cells and sex-cord stromal cells, a miscellaneous group of testicular tumors and paratesticular tumors. In addition, significant changes were also introduced in the 2018 AJCC TNM staging (8th edition) regarding testicular tumors. The germ cell tumors are divided into 2 major groups; tumors derived from germ cell neoplasia in situ (GCNIS) and those unrelated to GCNIS. The GCNIS associated tumors include seminomatous and nonseminomatous germ cell tumors, which constitute a heterogeneous group of tumors. Non-GCNIS-associated tumors include prepubertal-type teratoma, prepubertal yolk sac tumor, mixed prepubertal-type teratoma and yolk sac tumor and spermatocytic seminoma. In the sex cord-stromal category, the tumors are classified based on their cells of origin. Most are Leydig cell tumors and Sertoli cell tumors; however, several mixed and diverse entities based on cell types are included in this group. Gonadoblastoma is the only tumor in the mixed germ cell and sex cord-stromal tumor category. Because of recent advances in molecular techniques, abundant new genetic information has emerged which helped classify the tumors based on the molecular alterations and provided insights into the tumor pathogenesis. This review focused on the updates related to testicular germ cell tumors and sex cord-stromal tumors and described the morphologic, immunohistochemical and molecular characteristics with an aim to provide a practical diagnostic approach and an update on relevant recent molecular advances.

Immunohistochemical Characterization of 120 Testicular Sex Cord-Stromal Tumors With an Emphasis on the Diagnostic Utility of SOX9, FOXL2, and SF-1

Sex cord-stromal tumors (SCSTs) account for the second most common category of testicular neoplasms and include several entities that may show overlapping morphologies and present diagnostic challenges. We analyzed a cohort of 120 testicular SCSTs and investigated the diagnostic utility of SRY-box transcription factor 9 (SOX9), forkhead box protein L2 (FOXL2), and steroidogenic factor 1 (SF-1) immunohistochemical stains. The results were compared with the more commonly used SCST markers, inhibin α, calretinin, and Wilms' tumor 1 (WT1). SF-1 was overall the most sensitive stain (91%), followed by inhibin α (70%), calretinin (52%), FOXL2 (50%), SOX9 (47%), and WT1 (37%), but sensitivities varied by tumor type. SOX9 and calretinin were more commonly positive in sex cord elements versus stromal elements (62% vs. 27% and 47% vs. 9%, respectively), whereas FOXL2 was more commonly positive in stromal elements versus sex cord elements (100% vs. 55%) when excluding Leydig cell tumors from the stromal category. Although no individual stain was diagnostically specific, some immunophenotypic patterns were noted that may help in the subclassification of SCSTs. We conclude that SOX9, FOXL2, and SF-1 are useful immunohistochemical stains for confirming sex cord-stromal differentiation in testicular tumors and provide increased sensitivity as well as additional diagnostic information, especially when combined with the more commonly used inhibin α, calretinin, and WT1 immunostains. Although morphology is paramount for subclassification of SCSTs, knowledge of certain immunohistochemical patterns may be helpful for diagnostically challenging cases.

Therapeutic strategies for uncommon testis cancer histologies: teratoma with malignant transformation and malignant testicular sex cord stromal tumors

Testicular cancer is the most common solid malignancy in male adolescents and young adults, with germ cell derived seminomas and non-seminomas being by far the most common histologies. Teratoma with somatic-type malignancy is a rare chemo-resistant phenotype of testis cancer associated with poor prognosis in patients with advanced stage disease. Malignant gonadal-stromal tumors comprise 5% of testicular neoplasms and approximately 10% are malignant and considered chemo-radiation resistant. Prognostic factors and treatment strategies for these uncommon histologies are lacking.

Adult testicular granulosa cell tumour: an extremely rare entity

Adult granulosa cell tumours are extremely rare and usually benign but sometimes can assume an aggressive behaviour. A 31-year-old man presented with a 45 mm testicular mass. Radical orchiectomy was performed. Histological examination showed elongated cells, with hyperchromatic nuclei and Call-Exner bodies. Immunohistochemical analysis revealed positivity to vimentin, inhibin and negative PLAP and AE1/AE3 staining. The patient did not receive any adjuvant therapy and remained asymptomatic during 10 years. There are few cases of adult granulosa cell tumours and there is no consensus regarding malignancy criteria, treatment and follow-up. The description of these entities is crucial to allow a better management of these patients.

A Contemporary Review of Common Adult Non-germ Cell Tumors of the Testis and Paratestis

This article provides a comprehensive review of non-germ cell tumors of the testis and paratestis in adults, incorporating the latest 2016 World Health Organization updates. Clinical features, gross pathologic findings, key morphologic details, immunohistochemical profiles, and differential diagnoses are covered, with an emphasis on how to resolve commonly encountered, and sometimes difficult, differential diagnoses.

[Fibrothecoma of the testis: A case report in an adult]

Fibrothecal tumors belong to sex cord/stromal tumors (SCSTS). They represent 1 to 4.7 % of the organics tumors of ovary (Chechia et al., 2008) but are extremely rare in the testis, with only a few cases described in the literature. We report a new case of a fibrothecoma in the testis in an adult. The extemporaneous diagnosis was made in the same time of the surgical intervention. The castration has been avoided.

The World Health Organization 2016 classification of testicular non-germ cell tumours: a review and update from the International Society of Urological Pathology Testis Consultation Panel

The World Health Organization (WHO) released a new tumour classification for the genitourinary system in early 2016 after consensus by pathologists with expertise in these organs. It utilized the framework of the 2004 classification, and incorporated the most up-to-date information concerning these tumours. In testicular tumours, the majority of the changes occurred in the nomenclature and classification of germ cell tumours; however, several modifications were also made for non-germ cell tumours. Among sex cord-stromal tumours, sclerosing Sertoli cell tumour (SCT) is no longer recognized as a separate entity but as a morphological variant of SCT not otherwise specified (NOS), as CTNNB1 gene mutations have been noted in both neoplasms but not in the other forms of SCT. Similarly, the lipid cell variant is not separately classified, but is considered to be a morphological variant of SCT NOS. Large-cell calcifying SCT is recognized as a distinct entity that occurs either sporadically or in association with Carney complex, with the latter patients having a distinct germline PRKAR1A gene mutation. Intratubular large-cell hyalinizing Sertoli cell neoplasia is also accepted as a separate entity linked with Peutz-Jeghers syndrome. The subcategories of 'mixed' and 'incompletely differentiated' forms of sex cord/gonadal stromal tumours have been replaced by 'mixed and unclassified sex cord-stromal tumours'. New entities introduced in the latest WHO revision include: myoid gonadal stromal tumour and 'undifferentiated gonadal tissue', a putative precursor lesion of gonadoblastoma, whereas juvenile xanthogranuloma and haemangioma are included in the miscellaneous category of tumours.

Myoid gonadal stromal tumor: a clinicopathologic study of three cases of a distinctive testicular tumor

OBJECTIVES

To report three new cases of testicular myoid gonadal stromal tumor to better characterize its features.

METHODS

The clinicopathologic findings (including follow-up) were evaluated and a review of the literature was performed.

RESULTS

The patients were 38, 43, and 59 years old, and tumor sizes were 1.2, 1.3, and 3.2 cm. All were unilateral, well circumscribed, adjacent to the rete testis, and composed exclusively of spindled cells with elongated nuclei and occasional nuclear grooves arranged in fascicles with admixed variably ectatic blood vessels. Nucleoli were inconspicuous, and the cytoplasm was scant, ill-defined, and pale/lightly eosinophilic. No sex cord component was present. Mitotic figures ranged from zero to five per 10 high-power fields. Significant atypia, lymphovascular invasion, and necrosis were absent. All were consistently positive for smooth muscle actin, S100 protein, FOXL2, and steroidogenic factor 1 but negative for h-caldesmon, calretinin, and SOX9. Inhibin and calponin were focally positive. All patients were alive and well at 5, 31, and 58 months postorchiectomy. Combining our cases with those previously reported (n = 6) shows that this neoplasm occurs mostly in younger men (mean, 37 years), and all follow-up thus far (mean, 25 months) has been benign.

CONCLUSIONS

Myoid gonadal stromal tumors are small (<4 cm) indolent testicular tumors distinctly different from other sex cord-stromal tumors and are adequately managed by orchiectomy.

Adult granulosa cell tumors of the testis: a report of 32 cases

The clinicopathologic features of 32 adult granulosa cell tumors (AGCT) of the testis are presented. The patients were from 14 to 87 years of age (mean 40.0 y) and underwent orchiectomy (n=30) or wedge excision (n=2). None had endocrine-related symptoms. The tumors measured 0.5 to 6.0 cm (mean 2.8 cm) and were predominantly well circumscribed and yellow-tan, except for 1, which had infiltrative borders. The predominant pattern was diffuse, but insular, spindled, microfollicular (Call-Exner bodies), trabecular, corded, watered-silk, palisading, and pseudopapillary patterns were also present. The cells contained round to ovoid nuclei with frequent longitudinal nuclear grooves, indistinct cell borders, and varying amounts of eosinophilic cytoplasm. Most tumors contained limited amounts of fibrocollagenous stroma. The mitotic count ranged from 0 to 18/10 high-power fields (HPF) (mean 4.9/10 HPF, ×400). Two tumors had prominent necrosis, and 1 had vessel invasion. Follow-up information was available for 19 patients, with a mean of 51.0 months (range, 1 to 169 mo). All were without evidence of disease except 1 who had lung metastasis at 24 months. Our findings indicate that the morphologic spectrum of testicular AGCT is similar to that of ovarian AGCT. The majority of testicular examples have a good prognosis (compared with a malignant behavior in 2 of 7 cases in 1 prior series). Lymphovascular invasion, infiltrative borders, and size >4 cm may help in identifying cases with aggressive behavior, as these features were present in the one case with metastasis in our series. Mitotic counts varied and do not appear to be of prognostic significance on the basis of our experience.