Apocrine differentiation is usually seen
Often with decapitation secretion
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Outer layer of cuboidal myoepithelial cells
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Variable degree of mitotic index
Top Differential Diagnoses
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Syringocystadenoma papilliferum (SCP)
Similar histologic features, indicating that these are likely closely related tumors
Epidermal connections much more common in SCP
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Tubular apocrine adenoma
Simpler lesions composed predominately of tubular structures
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Nipple adenoma (erosive adenomatosis of nipple, florid papillomatosis)
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Papillary eccrine adenoma
TERMINOLOGY
Abbreviations
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Hidradenoma papilliferum (HP)
Definitions
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Small, well-circumscribed, dermal-based adenoma with apocrine differentiation
CLINICAL ISSUES
Epidemiology
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Incidence
Rare
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Age
Adult
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Sex
Almost always women
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Ethnicity
No race predilection