Unclassified Sex Cord/Gonadal Stromal Testis Tumour with a “Pure “Spindle Cell Component: Pathological Features And Review of The Literature

Abstract

Background: About 2-5% of adult testicular tumors are classified as sex cord/stromal tumors, which are an uncommon group of tumors of the testis. Occasionally, a small percentage of Sex Cord/stromal Testis Tumors (SCST) that are primarily composed of spindle cells seem to be unclassifiable. There are about six cases reported where spindle cells predominate, four of which are consisting purely of spindle cells. At the morphologic level, a striking resemblance to a fibroma has raised the notion of a possible fibrothecoma, but this is not supported by the immunohistochemistry, and the features are consistent with an unclassified sex cord/stromal tumor with a “pure” spindle cell component. Description: A 45-year-old man with a firm mass in the lower pole of the left testis for 3 years. The patient had no comorbidities and no features of endocrinopathies. All blood tests were normal. The ultrasound showed a solitary hypoechoic mass with increased blood flow by Doppler scan. A well-circumscribed tumor measuring 30mmx 15mm with no discernible capsule was identified macroscopically. Microscopy showed a well-circumscribed spindle cell lesion with no necrosis, cytological atypia, or mitoses. The tumor cells appeared spindled with eosinophilic cytoplasm, vesicular nuclei, and occasional nucleoli. No nuclear grooves were noted in the tumour cells. No vascular invasion was present. Actin, calretinin, CD99, S100, and inhibin were positively immunoreactive. Conclusion: The findings were consistent with an Unclassified pure spindle SCST, a rare tumor with a benign course that must be distinguished from several spindle cell neoplasms. There are no biochemical markers for the diagnosis of this tumor, thus requiring meticulous clinical examination, especially if it is small in size. We report a case of “pure spindle cell sex cord stromal tumour of the testis in a 45 years old man in which the histomorphological as well as the immunohistochemical features are consistent with the diagnosis of unclassified sex cord/stromal testis tumor with “pure” spindle cell component.