An 80-year-old man presents complaining of a very large oozing plaque on his scalp that has been slowly growing for more than a year. He claims that it is not painful, but he is concerned that it is ringworm.
The patient’s past medical history is significant for hypertension and thyroid disease for which he is treated medically. He denies any previous skin cancer or trauma to the area. On physical examination, the lesion measures 11 cm in diameter and is erythematous, ulcerated and oozing clear to yellow-colored discharge. What’s your diagnosis?
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This patient was diagnosed with squamous cell carcinoma. Nonmelanoma skin cancer is the most common cancer in the United States, with basal cell carcinomas (BCC) making up approximately 80% of all cases, followed by squamous cell carcinoma (SCC), at around 20%. Unlike BCC, however, cutaneous SCC carries a risk of metastasis.
SCC arises in the epithelium and is common in middle-aged individuals, the elderly and the chronically sun-exposed. The face, scalp, neck and dorsal hands are the favored locations due to long-term UV radiation. While BCCs outnumber SCCs on the face, SCCs are three times more common than BCCs on the hand.
Other risk factors for SCC include exposure to ionizing radiation, photo chemotherapy (PUVA) or arsenic, or having a skin type of 1 or 2 on the Fitzpatrick Skin Type Classification Scale, human papillomavirus types 6 and 11 or an immunocompromised state.
Actinic keratosis (AK) is the most common precursor to SCC. These lesions are small pink, brown or white papules with a sandpaper-like feel. About 15% of AKs ultimately transition into SCC. SCCs that progress from AKs are typically less aggressive than those arising de novo.
The classic presentation of SCC includes a hyperkeratotic, scaly plaque on an erythematous base. With time the lesion ulcerates, but often times the ulcer is hidden beneath an adherent crust. As the ulcer enlarges, it invades the underlying tissue.
The diagnosis is made almost exclusively via biopsy. Since SCC has numerous clinical presentations, there is a low threshold for biopsy. On histology irregular nests of epidermal cells invading the dermis characterize SCC.
Treatment and prognosis
Primary SCC treatment is surgical. However, aggressively treating precursor AKs can prevent SCCs from developing. Options include cryosurgery, topical chemotherapy, topical immunomodulators and photodynamic therapy.
According to the American Academy of Dermatology’s guidelines, low risk SCCs can be treated effectively with either electrodessication and curettage or standard excision.
High-risk lesions require Mohs micrographic surgery or radiation therapy. Radiation therapy offers a good cosmetic outcome and is tolerated well by the elderly, but is costly and not recommended for young patients. The aforementioned patient was treated with radiation with complete resolution in just five months.
Submitted online by Elizabeth A. McDonough, MPAS, PA-C. McDonough practices at Riverchase Dermatology in Naples, Florida.
- Habif TP. “Chapter 21: Premalignant and Malignant Nonmelanoma Skin Tumors.” Clinical Dermatology: A Color Guide to Diagnosis and Therapy. Hanover, NH: Mosby/Elsevier, 2004.
- James WD, Berger TG, Elston DM et al. “Chapter 29: Epidermal Nevi, Neoplasms, and Cysts.” Andrews’ Diseases of the Skin: Clinical Dermatology. Philadelphia: Saunders Elsevier, 2006.