Skin - Nonmelanocytic tumors
Adnexal tumors - eccrine sweat glands
Eccrine poroma

Author: Christopher Hale, M.D. (see Authors page)

Revised: 5 October 2016, last major update June 2012

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PubMed Search: Eccrine poroma

Cite this page: Eccrine poroma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/skintumornonmelanocyticeccrineporoma.html. Accessed December 10th, 2016.
Definition / General
  • Palms and soles, also other sites
  • Benign, although eccrine porocarcinomas also exist
  • May be a subtype of eccrine acrospiroma

Malignant eccrine poroma
  • Also called porocarcinoma
  • Most common sweat gland carcinoma
  • Usually lower extremities, may be pedunculated
  • Recurs locally, also metastasizes to regional lymph nodes
Case Reports

Malignant eccrine poroma
Gross Description
  • Sessile or slightly pedunculated nodule with normal or erythematous color, firm consistency
  • May ulcerate at points of pressure
Micro Description
  • Cords and nests of small keratinocytes attached to the epidermis
  • Nests are sharply delimited from adjacent epidermis
  • Also ducts and sharply delimited islands of squamous epithelium
  • Either intraepidermal (“hidroacanthoma simplex”), intradermal (“dermal duct tumor”) or mixed (most common)
  • Dermis has reactive vessels and inflammatory infiltrate
  • Also heavily pigmented variants

Malignant eccrine poroma
  • Malignant eosinophilic and clear cells in lobular masses or islands with cystic cavities due to extensive necrosis
  • Eosinophilic cells are polyhedral or fusiform with variable cytoplasm, hyperchromatic nuclei, distinct nucleoli, indistinct cell boundaries
  • Clear cells are large and polyhedral with abundant clear cytoplasm and distinct cell borders
  • Resembles eccrine poroma, but with obvious atypia and frequent mitotic figures
  • Also epidermotropism resembling Paget’s disease
  • Variable squamous differentiation, clear cell change and pigmentation
  • Either horizontal pattern (intraepidermal, like superficial spreading melanoma) or nodular (into dermis, like nodular melanoma)
Micro Images

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Eccrine poroma



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Eccrine poroma

Malignant eccrine poroma - High grade tumor invades dermis and subcutis

Positive Stains
Electron Microscopy Description
  • Features of eccrine gland acrosyringium
Differential Diagnosis

Malignant eccrine poroma - horizontal pattern:
  • Intraepidermal poroma: no atypia
  • Seborrheic keratosis: no atypia
  • Bowen’s disease: more atypical keratinocytes, more severe architectural abnormalities
  • Paget’s disease: large cells, clear cytoplasm, mucin+

Malignant eccrine poroma - nodular pattern:
  • Squamous cell carcinoma: prominent keratinization, keratin pearls, no cystic cavities
  • Sebaceous carcinoma: clear cells with bubbly cytoplasm
  • Proliferating trichilemmal tumors: solid and cystic, well demarcated with palisading of peripheral layer
  • Metastatic renal cell or other clear cell tumors
  • Balloon cell melanoma