Sex Cord Stromal Tumor, Mixed/Unclassified
Steven S. Shen, MD, PhD
Jae Y. Ro, MD, PhD
Key Facts
Terminology
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Group of SCST with mixture of recognizable types
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SCST with incomplete differentiation or undifferentiated spindle cells or mixed spindle and epithelioid cells
Clinical Issues
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Extremely rare (< 1% of testicular neoplasms)
Macroscopic Features
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Well-circumscribed, lobulated, white-yellow nodule
Microscopic Pathology
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Mixture of growth patterns and mixture of recognizable SCST components (LCT, SCT, or GCT)
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Mixture of epithelioid and undifferentiated spindle cell components
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Epithelioid component forms solid or hollow tubules, irregular aggregates, or anastomosing trabeculae
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Round to ovoid cells with eosinophilic, amphophilic, or vacuolated cytoplasm
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Undifferentiated stromal cell component is usually hypercellular spindle cells and merged with fibrous stroma
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Features that are seen more often in malignant tumors: Invasive growth, angiolymphatic invasion, nuclear atypia, mitotically active, and areas of necrosis
Ancillary Tests
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Positive for vimentin, desmin, actin-sm, S100, CD99, cytokeratin (may be focal), inhibin and calcitonin (focal)
TERMINOLOGY
Abbreviations
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Sex cord stromal tumor (SCST), Leydig cell tumor (LCT), Sertoli cell tumor (SCT), granulosa cell tumor (GCT)
Definitions
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Group of SCSTs with mixture of recognizable cell types or composed of incomplete or undifferentiated sex cord stromal cells
CLINICAL ISSUES
Epidemiology
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Incidence
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Extremely rare (< 1% of testicular neoplasms)
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Age
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All ages
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More commonly seen in children (30% < 1 year old)
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Presentation
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Painless testicular enlargement
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15% associated with gynecomastia
Treatment
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Surgical approaches
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Surgical resection is usually curative
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Testis sparing partial orchiectomy may be possible
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Radical orchiectomy with retroperitoneal lymph node dissection may be required for patients with clinical evidence of metastasis or high-risk pathologic features
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Prognosis
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Almost always benign in prepubertal children
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May be malignant in adults (20%)
MACROSCOPIC FEATURES
General Features
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Well-circumscribed, lobulated, white-yellow, nodular mass; similar to other SCST with no unique gross features
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Cystic areas may be seen
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Hemorrhage and necrosis are uncommon
MICROSCOPIC PATHOLOGY
Histologic Features
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Mixture of recognizable SCST components (Leydig cell, Sertoli cell, or granulosa cell, rarely theca cells)
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Mixture of undifferentiated or unclassifiable epithelioid and spindle cell components
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Epithelioid component
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Solid or hollow tubules, irregular aggregates, or anastomosing trabeculae (SCT)
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Round to ovoid cells with eosinophilic, amphophilic, or vacuolated cytoplasm and prominent nucleoli (LCT)
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Oval round cells with nuclear grooves, Call-Exner-like bodies (GCT)
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Mixture of above mentioned recognizable SCST
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Unclassified epithelioid cells with vesicular nuclei, occasional prominent nucleoli, rare mitotic figures
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Signet ring cell SCST has been reported
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Undifferentiated spindle cell component
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Usually hypercellular spindle cells merged with fibrous stroma
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Spindle cells may form fascicles
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Spindle cells may have nuclear grooves
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Cellular pleomorphism and mitotic figures are variable
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Has been reported as a variant of granulosa cell tumor because of its immunohistochemical similarities
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Features that are more commonly associated with malignant outcome: Invasive growth pattern, angiolymphatic invasion, nuclear atypia, mitotically active, and areas of necrosis
Predominant Pattern/Injury Type
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Neoplastic; diffuse spindle cells, mixed epithelioid and spindle cells, or combined form of known SCSTs
Predominant Cell/Compartment Type
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Sex cord stromal cells
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