Christine J. Ko, MD

Low-magnification view of a hidradenoma shows a dermal-based, nodular-appearing solid image to cystic image tumor.

High-power view shows a hidradenoma. Variable proportions of cell types are seen in any given tumor. In this field, clear cells image and squamoid cells forming focal keratin pearls image are present.



  • Clear cell hidradenoma, nodular hidradenoma, solid-cystic hidradenoma, cystic hidradenoma, eccrine acrospiroma, eccrine sweat gland adenoma, clear cell myoepithelioma, poroid hidradenoma, apocrine hidradenoma


  • Benign tumor showing apocrine or eccrine differentiation



  • Solitary dermal nodule


  • Excision is generally curative


  • Benign

  • Low malignant potential; may rarely transform to hidradenocarcinoma


Histologic Features

  • Well-circumscribed dermal-based tumor

    • Classically does not connect to epidermis and is deep-seated

  • May be primarily composed of solid areas, or cystic areas, or both

  • Solid areas composed of varying proportion of clear cells, poroid cells, squamoid cells, and rarely mucinous cells

  • Ducts with eosinophilic cuticles present in solid areas

  • Cystic areas lined by cuboidal cells, sometimes with evidence of decapitation secretion

  • Stroma between solid islands &/or cystic areas is prominently hyalinized appearing

  • Prominent cytologic atypia not present

  • Mitoses can be present, but usually not numerous

  • Necrosis usually absent

  • Generally does not show infiltrative pattern

Cytologic Features

  • Variable cell composition

    • Clear cells

      • Clear cytoplasm

      • Nuclei oval to round with small nucleoli

      • Contain glycogen and are PAS positive (diastase-sensitive)

    • Squamoid cells

      • Resemble keratinocytes with eosinophilic cytoplasm and well-demarcated cytoplasmic borders

    • Poroid cells

      • Basaloid cells with little cytoplasm

      • Nuclei have blue outlines and single nucleoli or occasionally multiple small nucleoli


Metastatic Renal Cell Carcinoma

  • Composed of clear cells arranged in variably sized islands

  • Vascular pattern may be prominent

  • Often extravasated erythrocytes numerous

  • Generally does not show cystic areas

  • More commonly CD10 and EMA positive

  • Positive with renal cell carcinoma antigen (RCA)


  • Cellular, atypical nodular dermal-based tumor

  • Shows greater cytologic atypia and mitotic figures and often has infiltrative features

Jul 8, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Hidradenoma

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