• In situ: Latin for 'in place': abnormal cells that look like cancer but have not yet broken through the layer they started in.
• Keratoacanthoma: the tumour that may be a squamous cell carcinoma: A dome-shaped lump with a central plug of keratin that grows fast over a few weeks and may then shrink on its own.
• The subtype and grade on a cutaneous squamous cell carcinoma report: A squamous cell carcinoma report carries two separate things: a subtype, which is the shape the tumour grows in, and a grade, which is how much it still looks like normal skin.
• Actinic keratosis (solar keratosis): sun damage, not cancer: Rough, scaly patches on skin that has had a lot of sun, commonest on the scalp, face, ears, forearms and backs of hands.
• Keratinocyte cancer (and why 'non-melanoma skin cancer' is being retired): The two commonest cancers in the world, basal cell carcinoma and cutaneous squamous cell carcinoma, both arise from keratinocytes, the cells that make up most of the outer layer of skin.
• Squamous cell carcinoma: A carcinoma arising from the flat, layered cells that line surfaces exposed to wear: skin, mouth, throat, oesophagus, cervix, the larger airways.
• Why nobody knows how many skin cancers there are: the counting rule behind every figure: Cancer registries were never built to count a cancer that people get several of.
• Inherited syndromes that cause skin cancer: Gorlin syndrome and xeroderma pigmentosum: Two rare inherited conditions cause skin cancer decades earlier and in far greater numbers than sun exposure alone.
• How skin carcinoma is staged in Britain: UICC TNM, and why it is not the American system: UK skin carcinoma reports are staged against the UICC's system, not the American AJCC's, and the two are not the same: the American manual covers only the head and neck, while the UICC covers the whole body and includes basal cell carcinoma.
• What makes a skin cancer high risk: the UK feature lists: Low risk and high risk are the words that actually decide what happens to a keratinocyte cancer in Britain, more than any stage.

Biomarker results to ask for: The word 'in situ' or 'intraepidermal' on the report, which is the whole diagnosis: the basement membrane is intact, pTis in the UICC staging system UK reports use, which is stage 0, Basaloid Bowen's disease, which may be the origin of the basaloid variant of invasive squamous cell carcinoma and stains weakly to focally with BerEP4 (RCPath G124), Whether invasive squamous cell carcinoma is present alongside it, which changes the diagnosis to the invasive cancer and is itself treated as a high-risk feature.

Scans and tests linked to this cancer: Histopathology & immunohistochemistry, Dermoscopy, total-body photography & AI skin analysis.

Bring copies of scan reports, pathology and blood results, and a list of every medicine and supplement.

• Typical lesion: Topical fluorouracil or imiquimod, cryotherapy, curettage and cautery, photodynamic therapy, surgical excision, Mohs surgery, radiotherapy or laser; Cancer Research UK states that all of these can work well and that cure rates are high. The choice is driven by the site, the size, how well the skin there heals and what the person can manage at home. The treatment layer of this family carries the detail. (Fluorouracil (5-FU), Imiquimod, Aminolevulinic acid (topical, for photodynamic therapy), Mohs surgery)
• If invasion is found: The diagnosis becomes invasive cutaneous squamous cell carcinoma and is managed on that pathway, with the adjacent Bowen's disease itself usually counted as a high-risk feature of the invasive tumour (RCPath G124). See the cutaneous squamous cell carcinoma page. (Wide local excision, Mohs surgery)

From the standard of care recorded for this cancer; which apply depends on your stage and biomarkers. Ask which the team recommends and why.