Mohs Micrographic Surgery in Ethnic Skin

10.1Introduction

Skin cancer is the most common malignancy in the United States [1]. While skin cancer is less common in ethnic skin, it is associated with increased incidence of morbidity and mortality as compared with Caucasian counterparts [2, 3]. This imbalance raises public health concerns. While current skin cancer campaigns focus on Caucasians in high-risk groups, little is known about sun protective behaviors in patients with ethnic skin. Additionally, many physicians do not immediately associate skin cancer with ethnic skin. Published

B.A. Jackson

Department of Dermatology, Skin Wellness Center of Chicago,

SC, Chicago, IL, USA

Northwestern Medical School, Chicago, IL, USA e-mail: bjacksonmd@mindspring.com

literature on skin cancer in ethnic skin is scarce, and collection of statistics for skin cancer in ethnic groups has proven difficult as non-melanoma skin cancers (NMSC) are not consistently reported to tumor registries and many NMSCs in ethnic skin are reported as melanomas. According to the 2000 census [4], 50% of the US population will be non-white by the year 2050. This changing demographics, combined with disparate morbidity and mortality in patients of color, underscores the importance for increased physician familiarity with skin cancer in ethnic skin so that we may better educate our patients on the risk factors, prevention, early detection, and treatment options of this highly treatable disease. Mohs micrographic surgery (MMS) is a highly effective treatment option for the treatment of some skin cancers [5]. While there is no difference in the MOHS surgical technique in ethnic skin, caution must be taken to minimize tension on surgical wound closures because of increased risk of keloid formation in ethnic skin [6, 7].

Summary: Histologic Differences in Skin of Color

•Ethnic skin has unique histologic features which allow some intrinsic photoprotection; however, the incidence of NMSC continues to increase in ethnic skin, suggesting there are other contributing factors.

10.2 Histologic Differences in Skin

of Color

While all skin, regardless of its color, contains the same number of pigment-producing melanocytes, melanosomes in darkly complected individuals are larger and more evenly dispersed throughout the entire epidermis as compared to the less active and clumped melanocytes in white skin [8]. These larger melanocytes allow dark skin to filter almost twice as much ultraviolet B (UVB) radiation than white skin [9], resulting in an estimated sun protection factor of 13.1 in black skin [10]. These unique histologic features of dark skin serve to protect it against actinic damage, making sun-induced skin cancers less prevalent. Despite this intrinsic photoprotection, the incidence of NMSC is increasing in skin of color [10], suggesting that UV exposure may play less of a role in the development of certain skin cancers in skin of color. Known risk factors for NMSC are listed below [11].

Known Risk Factors for NMSC

•Fitzpatrick skin types I–III

•UV exposure including UV light treatment

•Male gender

•Organ transplant immunosuppression

•Genetic disorders (XP)

•Chemical exposure(arsenic, heavy metal)

•HPV

Summary: Basal Cell Carcinoma (BCC)

•Classic presentation of BCC may be difficult to appreciate in skin of color and often occurs in non-sun-exposed areas of the body. Physicians should consider biopsy of any nonhealing or suspicious lesion in skin of color and educate patients with skin of color about risk factors and risk factor reduction.

Figs. 10.1–10.2 Eighty-year-old AA golfer with nodular BCC of L frontal scalp and R NLF

10.3 Basal Cell Carcinoma (BCC)

Studies have documented the correlation of BCC in African Americans to UV light exposure [12]; however, persons of color often have a false sense of security with regard to awareness of skin cancer risk and

Fig. 10.3 AA woman with nodular BCC postscalp

tend not to follow sun protection guidelines [13] proposed in skin cancer campaigns aimed at high-risk patients. Persons of color also have an increased incidence of medical conditions [14] such as diabetes, hypertension, and lupus necessitating the use of photosensitizing medications. These combined factors support the need for better counseling, patient education, and perhaps a distinct skin cancer awareness campaign directed toward ethnic skin.

While the classic presentation of a solitary pearly papule with rolled borders and central ulceration may occur in skin of color, pearly borders and surrounding telangiectasia may be difficult to appreciate in darker skin tones (see Figs. 10.1 and 10.2). Although BCC does occur in sun-exposed areas, in skin of color, it is seen with increasing frequency in non-sun-exposed sites [15] and often presents in an atypical manner [16], making diagnosis challenging (see Fig. 10.3). Physicians should therefore consider biopsy of any suspicious or non-healing lesion in persons of color (see Fig. 10.4). Histologically, pigmented BCC occurs more frequently in persons of color [15]. The differential diagnosis of BCC in ethnic skin is listed below.

DDX: BCC in Skin of Color

•Seborrheic keratosis

•Nevus sebaceous

•Lupus erythematosus

•Trauma (curling iron burn)

•Blue nevus

•Sarcoid

•Melanoma

Fig. 10.4 BCC cheek of Hispanic woman

Summary: Squamous Cell Carcinoma (SCC)

•Unlike Caucasian counterparts, SCC in skin of color occurs more commonly in non-sun- exposed skin and has a higher mortality rate.

10.4 Squamous Cell Carcinoma (SCC)

SCC is the most common skin cancer in African Americans [17] and the second most common skin cancer in Asians [18]. The precursor lesions to SCC, actinic keratoses, are common in Asians [19] yet tend not to occur in African Americans [20]. While SCC occurs with equal frequency on sun-exposed and non- sun-exposed skin in Caucasians, it is 8.5 times more likely to occur in non-sun-exposed areas (lower extremity, anogenital region) in African Americans, suggesting that UV radiation plays a less significant role in the development of SCC in African Americans [21, 22]. Although Bowen’s disease (SCC in situ) is less common in African Americans, it often occurs on the lower extremity presenting as a hyperkeratotic plaque. Mortality rates for African Americans with SCC are as high as 29% [23, 24] and are particularly high with anogenital lesions. These alarmingly high rates may be related to delayed diagnosis of tumors in non-sun- exposed areas combined with potentially more biologically aggressive tumors [23]. Risk factors for SCC are listed in Table 10.1 [17]. Because of the increased mortality rate with African Americans, physicians should counsel their patients regarding their risks of

Table 10.1 Risk factors for SCC in skin of color Risk factors for SCC in skin of color

Scars from burn or trauma

DLE/LE

Radiation sites

Immunosuppression

Chemical exposure (tar, arsenic)

Reprinted from Jackson [25]

Fig. 10.5 Bowen’s labelled as l cheek, it is actually l hip (close to the other cheek , lol)

SCC, evaluate new growths, and consider biopsy of any non-healing, ulcerated, or chronically inflamed lesion regardless of sun exposure (see Fig. 10.5).

Table 10.2 DDX for MM in skin of color

the leading cause of cancer death amongst young adults [27]. While family history and UV radiation exposure are risk factors for the development of malignant melanoma in Caucasians, they do not appear to play as significant a role in the development of MM in ethnic skin. Patients with skin of color are more likely to present with more advanced disease with lesions occurring more commonly in non-sun-exposed acral and mucosal areas [28]. In a recent study [29], the most common location of MM in African Americans was the foot (38.9%) compared with 2.4% of Caucasians where the most common primary location was the trunk (35%) compared with 7.1% of tumors in African Americans. Because survival rates are directly correlated with Clark’s level staging at diagnosis, early detection is critical for increased survival. Krementz et al. [30] documented that those African American patients diagnosed with early-stage MM and who received aggressive surgical treatment had the same favorable outcome as Caucasian patients. Differential diagnosis for MM in skin of color is listed in Table 10.2.

Summary: Malignant Melanoma (MM)

•Patients with skin of color are more likely to present with more advanced disease with lesions occurring more commonly in non-sun- exposed areas.

Summary: Treatment Techniques and Operative

Considerations

•Increased risk of keloid formation in skin of color warrants special care with closures under minimal tension. Standard treatments for hypertrophic scars and keloids are applicable for postsurgical wounds.

10.5 Malignant Melanoma (MM)

The incidence of malignant melanoma is increasing at a rate of 2.4% per year [26], suggesting that by the year 2010, 1 in 50 Americans will be diagnosed with melanoma. Malignant melanoma is the third most commonly diagnosed cutaneous malignancy in Caucasians, African Americans, Hispanics, and Asians [27] and is

10.6 Treatment Techniques and

Operative Considerations

Treatment techniques for skin cancer in ethnic skin of color do not differ from those used in Caucasian patients and are addressed more fully in other chapters of this text. Keloidal scar formation can occur in any race; however, the rate of keloid formation in African