11 Skin Cancer Flashcards
What are the common cutaneous malignancies?
Cutaneous malignancies are classified into melanoma and nonmelanoma skin cancers. Nonmelanoma skin cancers include basal cell carcinoma and squamous cell carcinoma, which account for the majority of all skin cancers. Melanoma skin cancers account for only 5% of cutaneous malignancies, but result in 90% of the mortality from skin cancer in patients less than 50 years old.
Rare nonmelanoma skin cancers include Merkel cell carcinoma, dermatofibrosarcoma protuberans, sebaceous carcinoma, and cutaneous T-cell lymphoma. Overall there are more skin cancers in the United States population than all other malignancies combined, and it is estimated that 20% of the population will develop a skin cancer during their lifetime.
What is a basal cell carcinoma?
Basal cell carcinoma (BCC) is a cutaneous neoplasm that arises from the basal layer of the epidermis. It is the most common skin cancer in humans, representing 75% of all nonmelanoma skin cancers with estimates of up to 1.5 million BCCs being diagnosed in the United States each year. There are many different classifications of BCC based on the tumor’s histologic appearance under the microscope, including:
- superficial
- nodular
- micronodular
- desmoplastic
- pigmented
- basosquamous
The classic appearance of a BCC is a skin-colored to pink, pearly papule or plaque with a rolled border and possibly central ulceration (Figures 11-1A and 11-1B). Superficial BCCs present as thin, pink, scaly papules or plaques and are most common on the trunk in younger patients (Figure 11-1C). Desmoplastic BCCs, also known as morpheaform, infiltrating or sclerosing BCCs, may have a more subtle clinical appearance, presenting as a flat, slightly atrophic lesions, similar to a scar (Figure 11-1D). Desmoplastic and basosquamous BCCs have a more aggressive clinical course and a higher risk of recurrence. Risk factors for BCC include fair skin, ultraviolet exposure, immunosuppression, ionizing radiation, exposure to chemicals such as arsenic, and rare genetic syndromes. Although BCCs can be locally aggressive, they almost never metastasize.
What is squamous cell carcinoma?
Describe PE finding.
Squamous cell carcinoma (SCC) is the second most common cutaneous malignancy and arises from the keratinocytes within the epidermis. SCC represents up to 25% of all skin cancers, but can have a more aggressive clinical course than BCC.
SCC-in-situ, also known as Bowen’s disease, is confined to the epidermis and presents as a thin, pink, scaly papule or plaque (Figure 11-2A). Invasive SCC presents as a pink, crusted papule or nodule on sun-damaged skin (Figure 11-2B). Common locations are sun-exposed areas such as the face, forearms and dorsal hands. SCCs associated with human papillomavirus (HPV) can occur on the hands, feet, and genitals. SCCs can also occur in areas of chronic inflammation such as a stasis ulcer or burn site (Marjolin’s ulcer). Risk factors for SCCs include fair skin, ultraviolet exposure, immunosuppression, smoking, HPV, ionizing radiation, exposure to chemicals such as arsenic, certain medications, and rare genetic syndromes. The risk of metastatic SCC is less than 5% in sun-exposed skin but can be significantly higher for high-risk tumors. Metastases are most commonly found in regional lymph nodes but can also be distant. The role of sentinel lymph node biopsy in high-risk SCC is debated.
What makes a squamous cell carcinoma high risk?
SCCs are considered high risk based on several factors including location, etiology, histologic features, and host immune status. High risk factors include the following:
- Location: ear, lip, and genitalia
- Etiology: association with HPV, chronic inflammation, radiation, chemical exposures
- Histology: poor differentiation, >2 cm size, >4 mm depth of invasion, perineural invasion, recurrence
- Host immune status: immunosuppression, genetic DNA repair defects such as xeroderma pigmentosum
What are the most common cutaneous malignancies in the transplant population?
Transplant patients are more likely to develop numerous, aggressive nonmelanoma skin cancers and should be counseled on the importance of sun protective measures, regular skin exams, and self skin checks. While BCCs are the most common cutaneous malignancy in the general population, SCCs are by far the most common cutaneous malignancy in transplant patients. Transplant patients are 100 times more likely to develop SCCs than the general population and 10 times more likely to develop BCCs. Reported increased incidence of melanoma varies from 0 to 17 times higher for transplant patients. Merkel cell carcinoma is also seen more commonly in transplant patients. Rates of skin cancer development and skin cancer mortality increase with the length of immunosuppression, level of immunosuppression, and in patients with a baseline high risk for skin cancer. Mortality from skin cancer may approach 27% in cardiac transplant patients.
What is Merkel cell carcinoma?
Merkel cell carcinoma (MCC) is a rare cutaneous neoplasm that is more common in older, immunosuppressed individuals. It presents as a _rapidly enlarging pink or violaceous nodule on the head and neck or other sun-exposed area_s. MCC was felt to have a neuroendocrine origin for many years, however in 2008 it was discovered that a polyomavirus was present in the majority of MCCs and the tumor is now considered to be infectious in origin, similar to HPV-induced malignancies. MCCs rapidly grow and up to 30% are metastatic at presentation. Treatment consists of surgical excision, often with sentinel lymph node biopsy and lymph node dissection if necessary, followed by adjuvant radiation therapy to the surgical site and nodal basin. Even with therapy, outcomes are poor with 5-year mortality at 30%.
What is a keratoacanthoma and how is it treated?
Keratoacanthoma (KA) is a controversial entity that presents as an enlarging skin-colored or red nodule often with a central crater that may be filled with keratinous debris (Figure 11-3). KAs usually develop over a few weeks and then are often reported to spontaneously resolve over months, leaving a scar. KAs are generally solitary but can be multiple in certain genetic syndromes. Given the difficulty in distinguishing a KA from a well-differentiated SCC both clinically and histologically, these tumors are best considered a variant of well-differentiated SCC and treated as such.
What is an actinic keratosis and how is it treated?
An actinic keratosis (AK) is a precancerous lesion that presents as a skin-colored to pink, rough papule on sun-exposed skin (Figure 11-4). Often, AKs are more easily felt than seen and patients describe them as areas that develop a crust that later falls off and reforms. If left untreated, AKs can develop into invasive SCC at a rate of 1/10 to 1/1000 per year, which presents a significant risk in patients with a large burden of these lesions. As a result, it is recommended that AKs be treated in most cases rather than observed.
AKs can be treated individually with destructive mechanisms such as liquid nitrogen cryotherapy.
Larger numbers of actinic keratoses can be field treated with multiple modalities, including topical chemotherapy (5-fluorouracil), topical immunomodulators (imiquimod), photodynamic therapy (δ-aminolevulinic acid exposed to 415 nm blue light), chemical peels or laser therapy. AKs are not treated surgically, being nonmalignant, ill-defined, and often diffusely present across sun-damaged skin. The risk factors for AKs are similar to those for SCC.
What is actinic cheilitis?
Actinic cheilitis describes the precancerous sun-damage changes that typically occur on the lower lip of older adults. It is the mucosal equivalent of an actinic keratosis, but because of its location has a higher risk of transformation to SCC. Actinic cheilitis can present as discrete, rough papules or encompass the entire lower lip with scaling of the lip and blurring of the vermillion border.
Actinic cheilitis can be treated similar to AKs with cryotherapy, topical agents, or photodynamic therapy.
However, once SCC has formed within large areas of actinic cheilitis, removal of the entire affected area with vermillionectomy and mucosal advancement flap or CO2 laser ablation may be indicated.
What tumors can be treated with Mohs surgery?
MMS is predominantly used to treat BCC and SCC, as these comprise 95% of all skin cancers. However, more rare cutaneous tumors can also be treated with MMS (see Table 11-1). Certain types of cutaneous tumors may be treated with MMS using immunohistochemistry tissue stains to help better visualize the tumor cells. Many Mohs surgeons use immunohistochemistry stains such as MART-1 and/or Mel-5 to treat melanoma-in-situ (particularly the lentigo maligna variant) with MMS. Special stains have been used in MMS for extramammary Paget’s disease (cytokeratin 7) and SCC (AE1-AE3—high molecular weight keratin stain).
- Adenocystic carcinoma
- Apocrine/eccrine carcinoma
- Atypical fibroxanthoma
- Dermatofibrosarcoma protuberans
- Extramammary Paget’s disease
- Leiomyosarcoma
- Undifferentiated pleomorphic sarcoma
- Merkel cell carcinoma
- Microcystic adnexal carcinoma
- Mucinous carcinoma
- Sebaceous carcinoma
What are other treatments for nonmelanoma skin cancer besides Mohs surgery?
Other treatment options for nonmelanoma skin cancer include excision, electrodesiccation and curettage, cryosurgery, topical therapies or radiation therapy. Excision can be performed for BCCs and SCCs, anticipating margins of 4 to 5 mm from clinically visible tumor, and clear margins should be confirmed with histologic examination. Electrodesiccation and curettage is a destructive technique that allows for localized treatment of low-risk skin cancers without the need for sutures or histologic examination. However, the technique can result in suboptimal scars and lower cure rates than excision or MMS. Cryosurgery or topical treatments, including 5-fluorouracil, imiquimod, and photodynamic therapy, are best limited to treatment of superficial variants of SCC and BCC. Radiation can be used to treat skin cancers, but is often reserved for inoperable tumors, patients who cannot tolerate surgery, or adjuvant therapy after complete surgical removal.
What is vismodegib?
Vismodegib (Erivedge) is an oral small molecule chemotherapy that targets a mutation present in the majority of sporadic BCCs and in basal cell nevus syndrome. These BCCs have a mutation in the PTCH gene that leads to constitutive activation of the receptor “Smoothened,” which in turn leads to gene replication and BCC formation. Vismodegib inhibits this hedgehog signaling pathway and can lead to the resolution of existing BCCs and prevention of new BCCs. However, there is often tumor recurrence or rebound after discontinuing the drug. The medication is currently approved for locally advanced BCC or metastatic BCC. Vismodegib has several side effects including nonscarring alopecia, dysgeusia (alteration to taste), and muscle cramps and is teratogenic.
What is melanoma?
Melanoma is a malignancy that arises from aberrant growth of melanocytes, the pigment-containing cells that exist in the basal cell layer of the epidermis and also within moles (Nevi). Melanoma is most frequently seen in fair-skinned individuals with histories of intense, intermittent ultraviolet exposure. It is the most common cancer in female patients 25 to 29 years old. Approximately 75% of melanomas arise de novo and the remainder arise from existing nevi. The four main types of melanoma are:
- superficial spreading melanoma (70%)
- nodular melanoma (15% to 30%)
- lentigo maligna melanoma (up to 15%)
- acral lentiginous (5% to 10%).
- Less common variations of melanoma are desmoplastic melanoma and amelanotic melanoma.
What is the clinical appearance of melanoma?
Melanomas are usually heavily pigmented, with color variations of brown, black, and blue, but may also include red or pink areas as well as lighter areas that represent tumor regression. Melanomas are often asymmetric with irregular borders and variegated color. Common symptoms are pain, itching or bleeding. Amelanotic (nonpigmented) melanomas are much more difficult to diagnose clinically and often present as a pink, rapidly enlarging nodule that may ulcerate and bleed.
What are the ABCDEs of melanoma?
Asymmetry: Melanomas are not uniform in size, shape or color.
Border: Melanomas often have borders that are not smooth or clearly demarcated.
Color: Melanomas may contain varying shades of pigment and also colors such as red, white, and blue.
Diameter: Most melanomas are >6 mm (the diameter of a pencil eraser); however suspicious lesions <6 mm should still be biopsied.
Evolution: Patients with melanoma often note changes in shape, size, color or symptomatology. Any new pigmented lesion in a patient >35 years old should be evaluated.
What are lentigo maligna and lentigo maligna melanoma?
Lentigo maligna is defined as a variant of in situ melanoma with a characteristic histologic and clinical appearance. Lentigo maligna presents clinically as a slow-growing, irregularly hyperpigmented patch on sun-exposed skin (Figure 11-7). Lentigo maligna melanoma (LMM) represents lentigo maligna with areas of tumor invasion into the dermis, and is the third most common type of melanoma (up to 15%). Lentigo maligna and lentigo maligna melanoma are most commonly seen in elderly patients on sun-exposed areas.
