Squamous cell carcinoma
A malignant tumour originating from squamous cells on the outer layer of the skin.
Sunlight and ionising radiation predispose to the development epidermal dysplastic lesions:
Keratoacanthoma (KA) is a rapidly growing hyper-keratotic nodule with a central keratin plug. This is probably a low-grade malignancy that originates in the pilosebaceous glands. It is considered by some to be a variant of invasive squamous cell carcinoma. Most resolve spontaneously but they may rarely progress to invasive or metastatic carcinoma. Surgical excision is often advocated.
Bowen’s disease is squamous carcinoma in situ. It appears as a red patch or plaque with variable scaling on sun damaged skin. Such areas require 5-fluorouracil cream, cryotherapy or curettage.
Most squamous cell carcinomas present with a locally invasive and well-differentiated papule, nodule or plaque, which frequently ulcerate if left untreated. Sometimes they have a rolled everted edge. Squamous cell carcinoma metastasise initially to regional lymph nodes which should be examined.
Surgical excision is the treatment of choice; this may necessitate reconstruction and skin grafting. Lymph nodes should be examined and removed if involved. Radiotherapy is an alternative in patients unfit for surgery.