General and Systemic Histopathology, C601&C602
    Slide 154: Keratoacanthoma of Skin

    (Variety of Squamous Cell Carcinoma)

    This is an absolutely classic appearance for this lesion; at least in two dimensions.  Deep central crater, lined by highly atypical cells.  As always, start at the very edge of the biopsy to get oriented as to more or less normal skin.  Take note of the degree of actinic degeneration within the dermis.  Then move to the lesion itself. Stay on low  power to get the overall feel of this condition.

    See this slide with the virtual microscope.

    This is an important lesion to know, it's very common and almost always on sun exposed parts of the body. The backs of the hands and helix of the ears are very common sites. This lesion is difficult to distinguish from its more aggressive, invasive squamous cell carcinoma cousins. Although long thought to be some benign variant or transitional form of squamous tumor, we now consider this to be a low grade, locally invasive form of squamous cell carcinoma. Note the "cupped shaped" nature of the lesion. To see this important diagnostic feature, you will need to look at the slide on a white background. Other important microscopic features include keratin "pearls," and an advancing margin along the base of the lesion. There is no question, the cells of this tumor look a good bit wilder than they behave, still removing is the way to go.

     Skin Diseases Lab page | Previous Slide | Next Slide | Table of Contents

    Back to Home