SCC Flashcards
What is squamous cell carcinoma (SCC)?
SCC is a malignant proliferation of keratinocytes originating in the epidermis, often due to chronic sun exposure. It is locally invasive and has a higher metastatic potential than basal cell carcinoma.
What are the histopathologic features of SCC?
Atypical keratinocytes, keratin pearls, intercellular bridges, and invasive nests of squamous cells.
What are the major risk factors for SCC?
- Ultraviolet (UV) light exposure
- Chronic sun damage
- Fair skin
- Immunosuppression (e.g., organ transplant, HIV)
- Chronic wounds or scars (Marjolin ulcer)
- Arsenic exposure
- **Human papillomavirus (HPV) infection (types 16, 18)
Why are immunosuppressed patients at higher risk for SCC?
Immunosuppression (e.g., organ transplant, HIV) reduces immune surveillance, increasing the risk of aggressive SCC with a higher potential for metastasis.
What are the key clinical features of SCC?
SCC typically presents as a non-healing ulcer with heaped-up edges, red scaly plaques, or hyperkeratotic nodules on sun-exposed areas (face, ears, lips, hands).
How do SCC lesions typically present clinically?
SCC presents as erythematous plaques or nodules with scaling, crusting, ulceration, or increased pigmentation.
What are the common locations of SCC?
SCC most commonly occurs on sun-exposed areas, including the face, ears, scalp, neck, dorsum of hands, and lower lip (classic high-risk site).
What is the prognosis of SCC?
Most SCCs have an excellent prognosis with early excision, but higher risk of metastasis (esp. on lips, ears, or in immunocompromised patients).
What is the significance of perineural invasion in SCC?
Perineural invasion increases the risk of local recurrence, metastasis, and poor prognosis.
What is keratoacanthoma?
Keratoacanthoma is a well-differentiated variant of SCC that grows rapidly over weeks but may spontaneously regress.
What are additional precursor lesions for SCC?
Actinic keratoses are considered precursor lesions to SCC, especially in sun-damaged skin.
What is Marjolin ulcer?
Marjolin ulcer is an aggressive SCC arising in chronic wounds, burns, or scars, often with delayed diagnosis and higher metastatic risk.
What is Bowen disease?
Bowen disease is SCC in situ, presenting as a well-demarcated, scaly erythematous plaque without invasion beyond the basement membrane.
How is SCC diagnosed?
Biopsy (shave, punch, or excisional) confirming atypical keratinocytes, keratin pearls, and intercellular bridges.
What is the treatment for SCC?
- Surgical excision with 5-10 mm margins 2. Mohs micrographic surgery for high-risk locations (face, genitals, hands) 3. Electrodesiccation & curettage for low-risk, superficial SCC 4. Radiation therapy for inoperable cases.
When is systemic therapy considered for SCC?
Systemic therapies, including PD-1 inhibitors (Cemiplimab, Pembrolizumab), are used for metastatic or unresectable SCC.
What biopsy methods can be used for SCC diagnosis?
Shave biopsy, punch biopsy, or excisional biopsy can confirm SCC diagnosis.
What is the preferred surgical margin for SCC excision?
A margin of 5-10 mm is recommended to ensure complete removal and reduce recurrence risk.
