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Pathology for Urologists

Adenomatoid Tumor

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  • Benign tumor of mesothelial origin.
  • May also occur in other extratesticular serosal sites.
  • Most common tumor of testicular adnexa (30%).
  • Patient age range 18-79 years (usually seen in 30's or 40's).
  • Presents as incidental painless, small and solid intrascrotal mass.
  • Gross:
    • Circumscribed (<5 cm), unencapsulated, solid, firm gray-white mass (image A).
    • Usually arise in the head of epididymis, but may also arise in tunica vaginalis, tunica albuginea and rete testis.

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  • Histology:
    • Gland-like, cyst, tubules, cords, or isolated cells (image B), (image C), & (image D).
    • Tumor cells are cuboidal, flat, or ovoid cells with round nuclei and abundant dense cytoplasm.
    • May look like vessels and small cell cluster may show signet ring appearance.
  • Immunohistochemisty: positive for mesothelial-associated markers (calretinin+, WT1+ and CK5/6+).
  • Benign behavior and surgical excision is curative.
  • DDX:
    • Rare benign vascular tumors: vascular marker Fli-1+; calretinin- and WT1-.
    • Metastatic signet ring cell carcinoma: calretinin- and WT1-.


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