Diagnosis is confirmed via biopsy of the tissue or tissues suspected to be affected by SCC. For the<unk> , look under<unk>  biopsy. The pathological appearance of a<unk> <unk><unk>  varies with the depth of the biopsy. For that reason, a biopsy including the subcutaneous tissue and basilar epithelium, to the surface is necessary for correct diagnosis. The performance of a shave biopsy (see<unk>  biopsy) might not acquire enough information for a diagnosis. An inadequate biopsy might be read as actinic keratosis with follicular involvement. A deeper biopsy down to the dermis or subcutaneous tissue might reveal the true<unk> . An excision biopsy is ideal, but not practical in most cases. An incisional or punch biopsy is preferred. A shave biopsy is least ideal, especially if only the superficial portion is acquired. Characteristics Histopathologically, the epidermis in SCC in situ (Bowen’s disease) will show hyperkeratosis and parakeratosis. There will also be marked acanthosis with elongation and thickening of the rete ridges. These changes will overly keratinocytic<unk> s which are often highly atypical and may in fact have a more unusual appearance than invasive SCC. The atypia spans the full thickness of the epidermis, with the keratinocytes demonstrating intense mitotic activity, pleomorphism, and greatly enlarged nuclei. They will also show a loss of maturity and polarity, giving the epidermis a disordered or “windblown” appearance. Two types of multinucleated<unk> s may be seen: the first will present as a multinucleated giant<unk> , and the second will appear as a dyskeratotic<unk>  engulfed in the cytoplasm of a keratinocyte. Occasionally,<unk> s of the upper epidermis will undergo vacuolization, demonstrating an abundant and strongly eosinophilic cytoplasm. There may be a mild to moderate lymphohistiocytic infiltrate detected in the upper dermis. File:Histopathology of<unk> <unk>  carcinoma in situ.Histopathology of<unk> <unk>  carcinoma in situ (black arrow), compared to normal<unk> , showing marked atypia. File:Micrograph of<unk> <unk>  carcinoma in situ - 100x.Squamous<unk>  carcinoma in situ, showing prominent dyskeratosis and aberrant mitoses at all levels of the epidermis, along with marked parakeratosis. In situ disease Bowen's disease is essentially equivalent to and used interchangeably with SCC in situ, when not having invaded through the basement membrane. Depending on source, it is classified as precancerous or SCC in situ (technically<unk> ous but non-invasive). In SCC in situ (Bowen's disease), atypical<unk> <unk> s proliferate through the whole thickness of the epidermis. The entire tumor is confined to the epidermis and does not invade into the dermis. The<unk> s are often highly atypical under the microscope, and may in fact look more unusual than the<unk> s of some invasive<unk> <unk>  carcinomas. File:Micrograph of<unk> <unk>  carcinoma in situ - 400x.SCC in situ, high magnification, demonstrating an intact basement membrane. Image:Bowen disease (1).SCC in situ Image:Bowen disease (2).SCC in situ Image:Bowen disease (3).SCC in situ Image:Bowen disease (4).SCC in situ Erythroplasia of Queyrat is a particular type of Bowen's disease that can arise on the glans or prepuce in males, and the vulvae in females. It mainly occurs in uncircumcised males, over the age of 40. It is named for French dermatologist Louis Queyrat (1856–1933), who was head of the dermatology service of l'Hôpital Ricord, a venereal hospital in Paris, now Hôpital Cochin. Invasive disease In invasive SCC, tumor<unk> s infiltrate through the basement membrane. The infiltrate can be somewhat difficult to detect in the early stages of invasion: however, additional indicators such as full thickness epidermal atypia and the involvement of hair follicles can be used to facilitate the diagnosis. Later stages of invasion are characterized by the formation of nests of atypical tumor<unk> s in the dermis, often with a corresponding inflammatory infiltrate. File:Gross pathology of<unk> <unk>  carcinoma.Gross slice of a<unk> <unk>  carcinoma of the<unk> . File:Micrograph of invasive<unk> <unk>  carcinoma - 150x.Superficially invasive<unk> <unk>  carcinoma (SCCSI). These lesions often do not show the marked pleomorphism and atypical nuclei of SCC in situ, but demonstrate early keratinocyte invasion of the dermis. File:Micrograph of invasive<unk> <unk>  carcinoma - 200x.High magnification demonstrates the pleomorphism of the invading keratinocytes. File:Ulcer border of a<unk> .Invasive nests with characteristic large<unk> ed centers. Ulceration (at left) is common in invasive SCC. Degree of differentiation File:Micrograph of well-differentiated and invasive<unk> -cell carcinoma.Well-differentiated (and yet invasive) SCC, showing prominent keratinization and may form “pearllike” structures where dermal nests of keratinocytes attempt to mature in a layered fashion. Well-differentiated SCC has slightly enlarged, hyperchromatic nuclei with abundant amounts of cytoplasm. Intercellular bridges will frequently be visible. File:Micrograph of moderately differentiated and invasive<unk> -cell carcinoma.Moderately differentiated lesions of invasive SCC show much less organization and maturation with significantly less keratin formation. File:Micrograph of clear-cell<unk> -cell carcinoma.Poorly differentiated, where attempts at keratinization are often no longer evident. This is a clear-cell<unk> <unk>  carcinoma. The dysplastic<unk> s here infiltrate in cords through the dermis. Poorly differentiated SCC has greatly enlarged, pleomorphic nuclei demonstrating a high degree of atypia and frequent mitoses. File:Micrograph of clear-cell<unk> -cell carcinoma with focus of obvious<unk> -cell features, annotated.Poorly differentiated clear-cell<unk> <unk>  carcinoma. For this type of SCC, immunostains will likely be required to classify it unless other areas of the tumor show obvious<unk> <unk>  features such as seen here (arrow).
Squamous cell skin cancer
Basal-cell carcinoma
Melanoma
Mucosal melanoma
Wart
Animal-type melanoma
Actinic keratosis
Skin cancer