General
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• Ages 27 to 45 years
• Incidental finding; benign (Am J Surg Pathol 1990;14:1001)

Gross description
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• May be visible but usually small
• Single or multiple

Micro description
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• Resembles trophoblasts in chorion lavae
• Well defined hyalinized lesion, variably cellular, immediately below mucosa, composed of extravillous (intermediate) trophoblast cells with abundant amphophilic, glycogen rich or eosinophilic cytoplasm with vacuoles, irregular nuclei with degenerative features and possible atypia
• Occasional inflammatory cells, rare/no mitotic figures

Micro images
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Nodule just below surface with sparsely cellular stroma

Cytoplasmic vacuoles and nuclear enlargement

HLA-G+ (not necessarily cervix)

Positive stains
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• Keratin, PLAP, inhibin alpha, CK18, HLA-G, p63
• Variable HPL

Negative stains
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• Ki-67 (<8% positivity)

Differential diagnosis
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• Cartilaginous tumors
• Hyalinizing squamous cell carcinoma: definite squamous cells, atypia, HPL negative
• Placental site trophoblastic tumor: larger, has mitotic activity, not degenerative

Additional references
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• Hum Pathol 1999;30:687

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