A low-grade malignant proliferation of epidermal cells that recapitulates the basal cell layer of the normal epidermis or the adnexa. These neoplasms show no differentiation to any of the adnexal structures and may have epidermal contiguity which may be multifocal.

Breed Affected

Sex Affected


Site Predilection

Gross Appearance:
  • Cannot distiguish from basal cell tumor on clinical evaluation
  • Histopathology reveals the infiltrative nature of the tumor

There are histologic variants of basal cell carcinoma. These are:

A. Infiltrative type

May have an association with the overlying epidermis

Cords of primitive basaloid cells extend into the dermis and occasionally the subcutis

Tumor cells have small, hyperchromatic nuclei with scant cytoplasm

Mitotic figures may be numerous

Often an extensive proliferation of stromal fibroblasts

Tumor shows no adnexal differentiation which allows it to be differentiated from sebaceous epithelioma and infiltrative and malignant trichoepithelioma

B. Clear-cell type is uncommon.

Architecture is that of a solid basal cell carcinoma

Cells are large and polygonal

Cells have a clear or finely granular cytoplasm

Nuclei are ovoid and uniform, nucleoli small

Number of mitosis found may be quite variable.


Good following wide excision, may recur but metastasis not reported