Skin nonmelanocytic tumors
Adnexal tumors - apocrine sweat glands
Apocrine mixed tumor

Author: Aravindhan Sriharan, M.D. (see Authors page)
Editor: Sara Shalin, M.D.

Revised: 14 September 2018, last major update April 2015

Copyright: (c) 2002-2018,, Inc.

PubMed Search: Apocrine mixed tumor [title]

Cite this page: Sriharan, A. Apocrine mixed tumor. website. Accessed October 17th, 2018.
Definition / general
  • Head and neck region involvement is common - nose is most common site here
  • Extremities are less common - axilla is most common site here
Case reports
Gross description
  • Slow growing, painless, firm, deep dermal to subcutaneous nodule
Gross images

Images hosted on other servers:

2 different apocrine mixed tumors (Source)

Microscopic (histologic) description
  • Well circumscribed but unencapsulated, multilobulated mass in deep dermis or subcutaneous fat, with lobules separated by fibrous septae of varying width
  • Biphasic with both epithelial and stromal components
    • Epithelial: elongated branching tubular structures with two cell layers
      • Outer layer is cuboidal or columnar; inner layer is columnar with eosinophilic cytoplasm
      • "Decapitation" type secretion, often squamous metaplasia and basal nuclei
      • Often has areas of apocrine, follicular and sebaceous differentiation
      • Presence of any follicular or sebaceous features rules out PURE eccrine mixed tumor
      • Wide array of morphologies can be seen, with all types of differentiation along the folliculosebaceous unit
      • Occasional cases have neoplastic tubules connecting directly to normal follicular infundibulum
      • Follicular differentiation is the most common type of change in the epithelium and may include:
        • Keratinous cysts with infundibular keratinization
        • Isthmic epithelium
        • Hair bulbs with papillary mesenchyme
        • Matrical differentiation with basaloid, transitional and ghost cells
        • Trichohyaline granules
        • Vellous hair shafts
        • Anagen differentiation
      • Sebaceous differentiation may include single cells or islands of mature sebocytes
      • Metaplastic epithelial changes include clear cell change, columnar change, cytoplasmic vacuolization (may be abortive luminal differentiation), hobnailing, mucinous, oxyphilic, squamous
      • Metaplastic myoepithelial changes include clear cell change, collagenous spherulosis, hyaline cells, plasmacytoid cells, spindled cells
    • Stroma: chondroid, mucoid, or fibrous
      • Metaplastic stromal changes include adipocytic, chondroid and osseous ametaplasia
      • Adipocytic metaplasia may be extensive; some adipocytes may have Lochkern nuclei with a single small vacuole indenting the nucleus that resemble lipoblasts
  • In contrast to eccrine mixed tumors, apocrine mixed tumors do not have clear cell change, cribriform areas, osseous metaplasia (prominent), physaliphorous-like cells, pseudorosettes
  • Benign tumors may have:
    • Asymmetry
    • Mild nuclear pleomorphism within the ductal component
    • Multinucleated, bizarre, hyperchromatic cells
    • Infiltrative or pushing borders
  • Features suggestive of malignancy include:
    • Severe atypia
    • Markedly increased cellularity
    • Increased mitotic rate
    • Destruction of surrounding tissue
    • Tumor necrosis
Microscopic (histologic) images

Images hosted on other servers:

Retiform, racemiform, solid and cribiform areas

Differentiation toward folliculosebaceous - apocrine unit

Metaplastic changes in the epithelium

Changes in the myoepithelial component

Stromal changes, depicting myxoid change

Positive stains
Negative stains
Differential diagnosis
Additional references