Bowen's disease and SCC in situ explained

Squamous cells form much of the outer skin. In Bowen's disease, these cells look abnormal under the microscope but have not moved beyond the epidermis. The term in situ means in its original place. This is different from invasive [Squamous Cell Carcinoma](/conditions/squamous-cell-carcinoma/), which has grown into deeper skin.

The visible change may be a persistent rough, scaly, red, or crusted patch. It can resemble irritation or [Sun-Damaged Skin](/conditions/photoaging/), so a clinician may need a biopsy rather than relying on appearance.

Do not ignore a confirmed lesion because it is superficial. Your dermatologist will match treatment to the lesion's size, site, borders, and pathology. Choices can include [Cryotherapy (Lesion Removal)](/treatments/surgical-dermatology/cryotherapy-lesion-removal/), [Topical 5-Fluorouracil](/treatments/medical-dermatology/topical-5-fluorouracil/), or [Photodynamic Therapy](/treatments/laser-and-energy/photodynamic-therapy/). Use the recommended wound care and return for examination after treatment.

Arrange a dermatology review for a patch that persists, grows, becomes thicker, bleeds, forms an ulcer, or changes quickly. After treatment, report increasing pain, pus, fever, or redness spreading beyond the expected area. These signs need clinical assessment; they do not establish a diagnosis by themselves.

Ask whether the diagnosis was confirmed by biopsy, how the lesion differs from invasive cancer, which treatment is suitable, and what follow-up will check for residual or returning disease.