Basal Cell Carcinoma
A 75-year-old man in good health presented with a 1-year history of a growing skin lesion on his left temple (► Fig. 54.1). It bled occasionally. There was no previous history of skin cancer and he denied pain or weight loss. His past occupation was as a truck driver for 40 years. On physical exam, the 1-cm plaque lesion was slightly raised and friable. His facial nerve was fully intact. He had no parotid or cervical adenopathy. He had Fitzpatrick’s 2 skin type. The remaining head and neck exam was within normal limits. A punch biopsy was performed (► Fig. 54.2).
Basal cell carcinoma (BCC) is a malignant neoplasm of keratinocytes that is correlated with both genetic and environmental factors. Significant sun exposure is the most significant risk factor, with a majority occurring on the face and scalp. Other risk factors include radiation therapy, long-term immunosuppression, and basal cell nevus syndrome. Almost 90% of BCCs have a mutation in the Hedgehog signaling pathway.
Nodular BCC, the most common subtype, is commonly found on sun-exposed areas such as the head and neck. It classically appears as a telangiectatic pearly papule with rolled borders, which will often ulcerate in the center as it progresses. The differential diagnosis includes dermal nevus, seborrheic keratosis, amelanotic melanoma, and sebaceous carcinoma.
Superficial BCC, the second most common, appears most commonly as an erythematous patch or plaque on the trunk. The differential diagnosis includes eczema, dermatophytosis, psoriasis, Bowen’s disease, Paget’s disease, tinea corporis, and squamous cell carcinoma.
Morpheaform (sclerosing) BCC is an aggressive variant that appears as a white or pink plaque, which is often indurated with poorly defined borders. Differential diagnosis includes scar tissue and morphea.
Pigmented BCC appears as a hyperpigmented, sometimes pearly papule. Differential diagnosis includes malignant melanoma, compound nevus, blue nevus, appendageal tumor, seborrheic keratosis, and nodular melanoma.
A biopsy is the diagnostic procedure of choice. Biopsy can be performed either by shave biopsy, incisional (punch) biopsy, or excisional biopsy with primary closure. A shave biopsy can be performed, with the exception of morpheaform BCC or recurrent BCC in a scar, in which a punch biopsy is more effective. If an incisional biopsy is performed, it is important to include the thickest portion of the nodule and the periphery, including an edge of normal skin to show maturation, the deepest area of invasion, and skin transition.
Treatment of BCC is guided by the location of the lesion, the size, the depth, and the histopathologic subtype. While treatment is often surgical, several medical options are available, with radiation therapy being the treatment of choice for poor surgical candidates. Other options include topical imiquimod, photodynamic therapy, ingenol mebutate, and vismodegib. Topical imiquimod is approved for nonfacial superficial BCC. Photodynamic therapy and ingenol mebutate have also demonstrated benefits in patients with superficial BCC. Vismodegib, which targets a protein in the Hedgehog intracellular signaling pathway, is approved for treatment of both locally advanced and metastatic BCC.
The various modalities of surgical treatment include wide local excision with frozen section control, Mohs micrographic surgery, cryosurgery, and curettage. The cure rates with each of these techniques exceed 90% in most large series, depending on the subtype and location of the BCC. Excision with frozen section control is the historical and conventional standard. However, this technique has been criticized by some for not providing adequate control due to the difficulty in obtaining good frozen sections in functionally crucial and delicate facial areas. The concern is that in order to gain adequate frozen section control, more sacrifice of normal tissue may be required (up to 1 cm from the skin lesion). Therefore, Mohs micrographic surgery can be performed for BCC occurring on the head and neck because it allows for histopathologic evaluation of all margins and maximally preserves uninvolved tissue. Mohs surgery has the lowest 5-year BCC recurrence rates compared to other types of treatment.
Mohs micrographic surgery has the advantage of using a microscopic sampling technique to enable better preservation of normal tissues. Most studies have suggested less than a 1% recurrence rate for primary BCCs treated by Mohs surgery. In addition, Mohs surgery is the treatment of choice for morpheaform and infiltrating BCCs, recurrent BCCs, and other high-risk BCCs (nasal, ocular, and postauricular regions) where tissue conservation is of the utmost importance. The disadvantages of Mohs surgery are that it is more time-consuming and may possibly require two separate sittings for removal and reconstruction. Finally, radiation therapy offers advantages that include less patient discomfort and a nonsurgical option for patients in poor health who are not good surgical candidates. However, in large BCCs the cure rates are lower than for surgical resection. In addition, cosmesis is often rated inferior to surgical excision and may actually worsen over time. Curettage and cryosurgery are primarily reserved for the treatment of low-risk BCCs and are not appropriate treatment modalities for large, aggressive, deeply invasive tumors.
Surgical reconstruction may entail primary closure, skin grafts (full or split), or local tissue rearrangement. This patient underwent Mohs microrgraphic excision and primary closure. No undermining was done toward the eyebrow to prevent brow distortion and to maintain brow symmetry.
Patients diagnosed with sun-related skin cancer have a 30% to 40% chance of developing another cutaneous malignancy. Thus, routine follow-up is important for tumor surveillance. Furthermore, patients must be closely followed to guard against local recurrence. The earliest sign of recurrence should be biopsied and resected if positive. In addition, the avoidance of sun exposure and the use of sunscreens should be recommended.
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