Hidradenoma



Hidradenoma


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.


TERMINOLOGY


Synonyms



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


Definitions



  • Benign tumor showing apocrine or eccrine differentiation


CLINICAL ISSUES


Presentation



  • Solitary dermal nodule


Treatment



  • Excision is generally curative


Prognosis



  • Benign


  • Low malignant potential; may rarely transform to hidradenocarcinoma


MICROSCOPIC PATHOLOGY


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


DIFFERENTIAL DIAGNOSIS


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)


Hidradenocarcinoma



  • 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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