Sebaceous Carcinoma

Sebaceous Carcinoma

David Cassarino, MD, PhD

Scanning magnification of a sebaceous carcinoma shows a very large, nodular tumor in the dermis. Note the lack of epidermal attachments; however, there are focal entrapped follicular structures image.

Higher power examination of a sebaceous carcinoma shows a proliferation of markedly atypical clear cells with numerous mitotic figures image and abundant apoptotic cellular debris image.



  • Sebaceous adenocarcinoma


  • Malignant adnexal tumor of sebaceous cells

  • Often lacks clear cell features in poorly differentiated cases and may show basaloid or squamoid features, leading to high incidence of misdiagnosis


Unknown in Most Cases

  • Some cases likely due to solar (UV) damage, as most occur on sun-damaged skin of elderly


  • Strong association with Muir-Torre syndrome (MTS) in patients who have multiple sebaceous tumors &/or multiple keratoacanthomas and internal organ malignancies

    • Genes implicated include MLH1, MSH2, MSH6

      • Encode mismatch repair proteins

      • Mutations lead to microsatellite instability (MSI)

      • MSI assays and immunohistochemistry can be used to screen for Muir-Torre syndrome



  • Incidence

    • Uncommon tumors, but one of the more common types of adnexal carcinoma

  • Age

    • Most occur in elderly patients

  • Gender

    • Females have slightly higher incidence


  • Eyelids are by far the most common site (˜ 75% of cases)

  • Remainder of cases occur in other head and neck sites, followed by trunk, extremities


  • Nodular, firm, yellow-tan lesions

  • Often ulcerated


  • Surgical approaches

    • Complete excision is necessary to ensure local removal

    • Mohs excision is reported to be effective in most cases

    • Sentinel lymph node biopsy may be useful for staging purposes


  • Aggressive tumors with high incidence of metastasis (> 30% of cases) and generally poor prognosis unless discovered early


General Features

  • Dermal-based firm, nodular lesion


  • Usually 1-4 cm


Histologic Features

  • Dermal-based infiltrative, nodular to sheet-like tumor

  • Often with focal follicular &/or epidermal connections

    • Pagetoid involvement of epidermis may be seen in up to 30% of cases

  • Tumor consists of variably differentiated epithelioid cells

    • Clear cells often present but vary greatly in number

    • Well-differentiated tumors show prominent clear cell changes

      • Cells contain abundant cytoplasmic lipid, often producing multiple vacuoles and nuclear indentation

      • Nuclei are enlarged and vesicular or hyperchromatic-staining, with prominent nucleoli

    • Moderately and poorly differentiated tumors show few to rare clear cells

      • May be composed predominantly of basaloid or squamoid cells

      • Show prominent cytologic atypia and pleomorphism

      • Mitotic figures, including atypical forms, are usually abundant

    • Areas of necrosis, with comedonecrosis pattern, are common

    • Lymphovascular invasion present in significant percentage of cases

Cytologic Features

  • Enlarged, epithelioid cells with abundant cytoplasm and hyperchromatic or vesicular nuclei with enlarged nucleoli

    • Clear cells usually show cytoplasmic vacuoles and nuclear indentation

    • However, cells can also be basaloid (common) or squamoid (rare)



  • Sudan black B and oil red O (need frozen tissue)

    • Reactivity: Positive

    • Staining pattern

      • Cytoplasmic staining

  • Periodic acid-Schiff

    • Reactivity: Usually negative (indicating lack of glycogen)


Jul 8, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Sebaceous Carcinoma
Premium Wordpress Themes by UFO Themes
%d bloggers like this: