Skin nonmelanocytic tumor

Carcinoma (nonadnexal)

Mucoepidermoid carcinoma

Last author update: 1 November 2014
Last staff update: 30 March 2023

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PubMed Search: Mucoepidermoid carcinoma [title] skin

Ghassan A. Tranesh, M.D.
Hong Qu, M.D.
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Cite this page: Tranesh GA, Qu H. Mucoepidermoid carcinoma. website. Accessed October 2nd, 2023.
Definition / general
  • Mucoepidermoid carcinoma
    • Very rare in skin (~30 cases reported)
    • Probable sweat gland origin
    • Resembles similar tumor of salivary gland
    • Usually low to intermediate grade, some higher grade tumors perhaps better classified as adenosquamous carcinoma
  • Adenosquamous carcinoma
  • Adenosquamous carcinoma
    • Frequent confusion in the literature regarding this entity in the head and neck and high grade mucoepidermoid carcinoma (Int J Clin Exp Pathol 2014;7:1809)
    • More common in organs where adenocarcinoma arises frequently, including stomach, intestines and uterus (Oncol Lett 2014;7:1941)
Pathophysiology / etiology
  • Adenosquamous carcinoma
    • Although its pathogenesis is largely unknown, 4 hypotheses have been proposed:
      • Malignant transformation of both squamous and glandular-like cells originating from pleiotropic epithelial stem cells
      • Tumorigenesis of squamous metaplasia in columnar epithelium
      • Transdifferentiation of adenocarcinoma to squamous cell carcinoma
      • Coexistence of both carcinomas (World J Surg Oncol 2013;11:124)
  • Adenosquamous carcinoma
    • Neoplasm composed of an admixture or separate areas of squamous cell carcinoma and adenocarcinoma
    • Criteria for squamous cell carcinoma component are 2 or more of these features:
      • Intercellular bridging
      • Keratin pearl formation
      • Parakeratotic differentiation
      • Individual cell keratinization
      • Cellular arrangement showing a pavementing or mosaic pattern
    • Criterion for adenocarcinoma component is demonstration of intracytoplasmic mucin
    • World Health Organization Classification does not require intracytoplasmic mucin for diagnosis of adenocarcinoma in the presence of true glandular formation (Int J Clin Exp Pathol 2014;7:1809)
Case reports
  • Adenosquamous carcinoma
    • Surgical excision or Mohs microsurgery are common treatment options (Head Neck Pathol 2011;5:108)
    • Locoregional recurrence is not uncommon
Clinical images

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Adenosquamous carcinoma

Gross description
  • Mucoepidermoid carcinoma
    • Up to 0.6 cm, ulcerated and nonencapsulated
    • Flesh colored nodules, painless
  • Adenosquamous carcinoma
    • White nodular infiltrate into subcutaneous tissue
Gross images

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High grade mucoepidermoid carcinoma

Microscopic (histologic) description
  • Mucoepidermoid carcinoma
    • Circumscribed tumor, may not be attached to surface
    • Multilobulated nodulocystic tumor extending throughout dermis, exhibiting glandular and squamoid differentiation
    • Dermal lobules or cystic growth of low grade epidermoid, intermediate, mucinous cells and clear cells
    • Cribiform nests of epidermoid cells contain glandular spaces with mucin
    • Nuclei are mildly atypical and contain scattered mitotic figures
    • Peritumoral fibrosis is common
    • May have focal perineural invasion
  • Adenosquamous carcinoma
    • Infiltrative islands of squamous cell carcinoma with admixed mucin containing glandular structures, adenomatous changes and acinar formation
    • Glandular structures lined by low columnar epithelium, sometimes lined by an eosinophilic cuticle (ductular differentiation)
    • Perineural invasion relatively common (Arch Dermatol 2009;145:1152)
Microscopic (histologic) images

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Mucoepidermoid carcinoma, site unknown

Mucoepidermoid carcinoma, Alcian blue-PAS

Mucoepidermoid carcinoma, salivary gland

Adenosquamous carcinoma

Cytology images

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Mucoepidermoid carcinoma in salivary gland

Positive stains
Negative stains
Molecular / cytogenetics description
  • Mucoepidermoid carcinoma
    • CRTC1 rearrangements have been detected in cutaneous MEC (like salivary gland MEC) but translocation t(11,19) or MAML2 rearrangements not seen (unlike salivary gland MEC) (Br J Dermatol 2009;161:925)
Differential diagnosis
Mucoepidermoid carcinoma
  • Adenosquamous carcinoma:
    • High grade tumor, often involves epidermis, adenocarcinoma component is well differentiated
  • Metastatic salivary gland tumor:
    • Usually high grade
  • Mucinous metaplasia

Adenosquamous carcinoma
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