Histologic Variants of Squamous Cell Carcinoma of the Skin

Margaret H. Rinker, MD; Neil A. Fenske, MD; Leigh Ann Scalf, MD, and L. Frank Glass, MD, Division of Dermatology and Cutaneous Surgery, Department of Internal Medicine at the University of South Florida, Tampa, Fla.

Cancer Control. 2001;8(4) 

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Squamous cell carcinoma (SCC) is the second most common type of skin cancer, with basal cell carcinoma being the most common. However, some argue that an actinic keratosis should be considered as an SCC that is superficial.[1] If so, then SCC could be considered the most common type of skin cancer. The tumor typically appears as a papule or nodule,with varying degrees of hyperkeratosis and ulceration that arises on the sun-exposed skin of elderly patients (Fig 1). The disease has been linked to immunosuppression,arsenic exposure, radiation,chronic ulceration, and human papillomavirus (HPV) infection.[2] The histology reveals a proliferation of atypical keratinocytes that invade the dermis, with areas of detachment from the overlying epidermis. These anastomosing growths of cords and nests are composed of cells that have a glassy eosinophilic cytoplasm and enlarged nuclei. Mitotic figures,keratin pearls, and dyskeratotickeratinocytes are variably present.On higher power, intercellular bridges may be seen.

Squamous cell carcinoma. It typically appears as a papule or nodule, with varying degrees of hyperkeratosis and ulceration that arises on the sun-exposed skin of elderly patients.

While cutaneous SCC is usually easily treatable, it has the potential to recur locally and even metastasize,then leading to significant morbidity and mortality. Therefore,it is important to identify those tumors that are more aggressive and require closer follow-up and possible adjunctive treatments such as micrographic surgery, lymph adenectomy,or radiation therapy.Established prognostic factors include tumor size, depth of invasion,histologic differentiation,anatomic site, perineural invasion,rapid growth, history of previous treatment, host immunosuppression,and etiologic factors such as burn scars, radiation, and chronic ulceration ( Table ).[3] The histologic subtype has also been considered as a factor in determining the prognosis.Several histologic subtypes of SCC are described, including keratoacanthoma,acantholytic,spindle cell, verrucous, clear cell, papillary,signet ring, pigmented, and desmoplasticSCC. These variants of SCC are reviewed for their clinical and histologic features and the risk of recurrence and metastasis.


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