Cutaneous squamous cell carcinoma: Clinical sciences

Cutaneous squamous cell carcinoma, or cSCC for short, is the second most common form of skin cancer, the first one being basal cell carcinoma.

The most important risk factors for developing cSCC include ultraviolet light exposure, chronic immunosuppression, and a history of actinic keratosis. Timely diagnosis and treatment of these lesions are vital to ensure the best outcome for the patient.

When a patient presents with a chief concern suggesting cSCC, you should first obtain a focused history and physical exam. History typically reveals risk factors like fair skin and significant sun exposure or exposure to UV radiation. These patients might also report bleeding or rapid growth of the lesions as well as changes in the appearance of the lesion.

When evaluating any lesions concerning for skin cancer, make sure to do a full body exam to look for any other suspicious lesions. The physical exam typically reveals an ulcerated non-healing nodule with irregular borders and possibly signs of active or recent bleeding. There is often erythema and induration surrounding the nodule as well as areas of actinic keratosis. The lesion might be painful or tender. Finally, you might find lymphadenopathy, often in the axilla, supraclavicular, cervical, or inguinal region depending on the location of the lesion. Based on these findings, suspect cSCC.

Here’s a clinical pearl! Be sure to differentiate cSCC from basal cell carcinoma. Cutaneous basal cell carcinoma is often a non-healing, well-circumscribed pearly papule, nodule, or plaque with rolled borders. Even though both are found on sun-exposed areas of the skin, cSCC is more commonly found on the dorsal forearm and hands, and then the head and neck; while basal cell carcinoma is typically found on the face and neck.

Alright, once you suspect cSCC, your next step is to examine the lesion with dermatoscopy. Dermatoscopy is performed with a hand-held skin surface microscope that can allow you to better see the details of the lesion. Findings on dermatoscopic examination consistent with cSCC include the presence of keratin pearls, telangiectasias, or atypical vessels. There is often erythema and surrounding inflammation, as well as a reticular pattern within the lesion, ulceration, or blood spots.

Dermatoscopy can also show small white circles or structureless areas, which indicate areas of cellular regression or atypia. Keep in mind that dermatoscopy findings often vary depending on the exact stage and subtype of the cSCC.

Next, you need to confirm the diagnosis with a tissue biopsy. A punch biopsy is a good choice as it gives a representative sample of the pathologic tissue. So, you might find a proliferation of atypical keratinocytes and the classic appearance of keratin pearls, though other histological findings include cellular or nuclear atypia, keratinization, desmoplastic stroma, increased mitotic activity, poorly defined borders, or perineural invasion. There may also be invasion of the epidermis or even dermis by atypical cells. If you see these findings, that’s cSCC. Alternatively, if there are no characteristics of cSCC on biopsy, consider an alternative diagnosis such as cutaneous basal cell carcinoma, melanoma, dermatofibromas, or lipomas.