Introduction

Skin cancer is the most common malignancy in the U.S., predominantly studied in the Caucasian demographic [1, 2]. Unfortunately, this emphasis has resulted in a limited understanding of skin cancer in people of color (POC), who, despite a lower incidence of skin cancer, experience higher mortality rates [3]. Of particular concern is the underrepresentation of ethnic minorities in clinical research, leading to delayed diagnoses, varied treatment approaches, and poorer outcomes. This review aims to delineate the distinctive presentations of two rare cutaneous malignancies in POC: dermatofibrosarcoma protuberans (DFSP) and Kaposi sarcoma (KS). Additionally, we provide recommendations in managing these tumors in POC. Our goal is to address gaps in knowledge surrounding their manifestations, enhancing understanding and treatment of these rare skin cancers in POC. 

Methodology

Search Strategy

A comprehensive search from 1990 to 2023 was performed on PubMed using keywords such as ‘Dermatofibrosarcoma Protuberans’, ‘Kaposi Sarcoma’, and race-related keywords including ‘African American’, ‘Black’, ‘Hispanic’, and ‘Asian’. The terms ‘African American’ and ‘Black’ were used interchangeably based on source terminology and are equivalent in this review. We screened all identified articles for relevance, selecting those meeting our inclusion criteria for further analysis. References from relevant articles were also used to locate more articles for our study.

Inclusion and Exclusion Criteria

Our inclusion criteria comprised English articles published in peer-reviewed journals reporting on DFSP and KS within POC. Excluded were non-peer-reviewed publications, non-English articles, and articles not directly focusing on these malignancies.

Dermatofibrosarcoma Protuberans

Epidemiology of DFSP

DFSP is a rare, locally aggressive soft tissue sarcoma that accounts for 0.1% of all cancers, and has an overall incidence of 4.1 to 4.2 million in the U.S [4, 5]. Currently, existing knowledge regarding the epidemiology, histology, presentation, and treatment revolves around studies primarily performed in White populations.

Although rare, DFPS accounts for ~ 10% of all cases of skin cancer in Blacks, and occurs at rates nearly double those seen in Whites, rising to 3.5-fold among Blacks aged 45-49 [3]. Despite a higher prevalence in Blacks, there remains a scarcity of reports specifically addressing cases in POC [4, 5]. Given that DFSP in POC is underexplored, it is important that Dermatologists are aware of the existing pathophysiological and clinical disparities to best treat POC.

Clinical Presentation of DFSP

DFSP presents in various subtypes, such as Bednar, myoid, and fibrosarcomatous, each distinguished by unique histological features. Except for fibrosarcomatous, most subtypes generally have similar clinical outcomes [6]. While DFSP can appear at any age, it is most prevalent between the third and fifth decades of life [4]. DFSP initially presents as an asymptomatic, flesh-colored, indurated, firm nodule. Progression of the lesion can lead to pain, ulceration, and protuberant growth [7]. DFSP in Blacks often presents at a more advanced stage, often with a larger tumor size (> 3.0 cm) at presentation [8]. A study by Kreicher et al. concludes that larger tumor size and Black race are negative predictors of survival [5]. Moreover, the Bednar subtype, characterized by pigmented melanin-containing dendritic cells, is seven times more prominent in Black patients than White [9, 10]. While 77% of DFSP lesions in Whites are superficial, a study in Asians showed that 72% of DFSP lesions invaded subcutaneously and 89% progressed to the protuberant stage [11, 12]. Overall, initial clinical presentation of DFSP in POC is more severe and is strongly associated with poorer prognoses.

Histology and Imaging of DFSP

DFSP’s histology is consistent across races, with the Bednar tumor variant, marked by melanin-rich dendritic cells, more prevalent in Black individuals [4, 10]. Recent studies investigating the association between DFSP and female sex hormones have uncovered higher incidence rates potentially linked to elevated estrogen levels in African Americans, who have been demonstrated to have higher estrogen levels compared to Caucasians [5, 13, 14]. In contrast, research from China indicates no estrogen receptor positivity and only moderate progesterone receptor positivity in 29% of DFSP cases, suggesting racial and environmental differences in pathogenesis [15].

Misdiagnosis is a significant concern, particularly in Blacks, where DFSP is commonly mistaken for keloids [16]. Non-invasive imaging techniques, such as ultrasound, dermatoscopy, and MRI are crucial in this context as they provide detailed visual information that can differentiate DFSP from other skin conditions like keloids, melanoma, and dermatofibroma [17,18,19,20]. DFSP exhibits distinct dermatoscopic features. In Black patients, features of a pigmented network and pink background, telangiectasia, erythematous dome-shaped papillary outgrowths, and brown ill-defined areas can be observed [20]. These characteristic findings can help distinguish DFSP and assist dermatologists in achieving a more accurate diagnosis. CT can be performed to determine the underlying bone involvement or calcifications, and for staging purposes for distant metastasis in cases of aggressive lesions [18].

Treatment and Outcomes of DFSP

DFSP exhibits low metastatic potential (< 1–5%), and race has not been established as a significant prognostic factor for distant spread [4, 5, 11, 12]. Local recurrence is a characteristic concern, often due to the tumor’s infiltrative growth pattern and the difficulty in defining its margins [21]. Recurrence rates for DFSP are highly variable, ranging from 0 to 60%, depending on the treatment modality [11, 12]. Studies indicate Hispanic patients are more likely to undergo repeat surgeries for DFSP, suggesting a higher recurrence risk compared with non-Hispanic populations. No significant difference in the rate of secondary surgeries was observed between White and Black patients [22].

Complete surgical resection with wide local excision (WLE) or Mohs micrographic surgery (MMS) is the primary treatment for DFSP. MMS is preferred over WLE due to its advantages such as a lower recurrence rate (~ 1% vs. 6.3–8.8%), smaller surgical defects, and a reduced need for postoperative radiation therapy [8, 21]. Research by Criscito et al. reveals disparities in treatment selection, showing that MMS is more frequently administered to white patients, women, and individuals with high median household income, as opposed to Blacks, males, and lower median household income counterparts. Furthermore, Blacks were more likely to receive surgery and radiation rather than surgery alone [8]. These findings suggest that patient demographics and socioeconomic status (SES) can influence the choice of treatment for DFSP.

DFSP has an exceptionally high survival rate, exceeding 99% [4, 5]. However, factors such as advanced age, male sex, larger tumor sizes, fibrosarcomatous changes, and location on the head or extremities correlate with poorer outcomes [5, 8]. Kreicher et al.‘s analysis of the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) data spanning 2000–2010 revealed that Blacks had a 1.7 times greater all-cause mortality risk compared to Whites, suggesting that Black race could be a negative survival predictor [5]. Yet, this conclusion is not uniformly supported across all studies; some have not found Black race to be a standalone factor predicting higher mortality [4, 8, 22]. Instead, Trofymenko et al. identified insurance status as a more significant mortality predictor [22]. Similarly, Criscito et al. found no direct correlation between race and mortality risk when adjusting for tumor size, noting that larger tumor sizes, more common in Black patients, might explain this discrepancy [4, 8]. This aligns with observations of delayed presentation and larger tumor sizes in some Asian populations, as well as the tendency for Blacks to present with larger tumors.

Kaposi Sarcoma

Epidemiology of KS

KS is an indolent, vascular tumor with diverse clinical manifestations across various populations [23]. It is most widely recognized in immunocompromised individuals, including those with acquired immunodeficiency syndrome (AIDS) or solid organ transplant recipients (SOTR) [23, 24]. Four distinct subtypes exist: (1) Classic KS, observed in elderly men of Mediterranean and Eastern European descent; (2) endemic African KS, characterized by generalized lymph node involvement in children; (3) the HIV-related KS, in patients not undergoing highly active antiretroviral therapy (HAART), featuring extensive cutaneous and internal organ involvement; (4) iatrogenic KS, prevalent in immunosuppressed patients, also exhibiting widespread cutaneous and internal organ manifestations [23]. Although each form has unique features, all subtypes are associated with Human herpesvirus-8 (HHV-8) infection [23].

The introduction of HAART has led to a nationwide decrease in KS incidence among HIV-positive individuals in the U.S. Despite this overall decline, notable disparities persist in the incidence and survival rates of KS among various racial groups in the HAART era [24,25,26]. A study by Royse et al. reports a decrease in KS among White males, but an increase among Black males in the southern U.S. from 2000 to 2013 [27]. The incidence in Black males was six times higher, which is also supported by other studies analyzing SEER data [28,29,30,31]. In contrast, Asians have a notably lower incidence rate of 4.0 per 1,000,000 person-years [31]. Moreover, specific subgroups within the U.S. may exhibit higher KS incidence rates. Research indicates an annual increase of 1.5% in KS incidence among non-Hispanic Black men aged 20–34, with a significant 3.3% annual rise in the southern U.S., while rates remained stable in non-Southern regions [29]. Conversely, non-Hispanic White men experienced a significant annual decrease of 3.5% in KS incidence [29].

Clinical Presentation of KS

The clinical manifestations of the various subtypes exhibit some shared features, yet certain characteristics are more typical of specific forms. In all subtypes, cutaneous lesions typically appear as multiple, painless, violet-hued macules, papules, nodules, or plaques that do not blanch on pressure [32]. Early lesions, often asymptomatic, may present as pigmented macules or papules, ranging from pale pink to deep purple [32]. The characteristic violaceous hue can be less discernible in individuals with darker skin tones, posing diagnostic challenges in POC [33, 34].

Some lesions may form large plaques, typically oblong and aligned with skin creases, or progress to exophytic, ulcerated nodules with associated bleeding and painful edema [22]. While clinical diagnosis is possible, histological confirmation is essential to avoid misdiagnoses, which may be more common especially among POC.

Histology and Imaging of KS

Biopsy and histological confirmation are standard for suspected KS cases, but this can be challenging in resource-poor settings [32]. In Africa where KS is prevalent, clinical observation is often the sole means of establishing a diagnosis of KS. An East African study indicated that clinical observation alone resulted in an 77% positive predictive value for diagnosing KS [35]. Consequently, some patients were erroneously diagnosed with KS, leading to administration of unnecessary chemotherapy [35]. Histopathologically, KS is diagnosable with hematoxylin and eosin staining, which reveals universal features across all variants of the disease [32]. These include dermal vascular proliferation with slit-like spaces, increased numbers of vessels without endothelial linings, the presence of hyaline globules from extravasated blood, hemosiderin deposition, and associated inflammatory infiltration. Spindle cell proliferation is a hallmark of KS, with these neoplastic cells exhibiting endothelial markers. While spindle cells often form organized structures such as sheets or fascicles, their detection in early KS lesions can be challenging [32]. PET CT or CT imaging is standard for detecting visceral involvement in all KS patients [36].

Treatment and Outcomes of KS

There is no known treatment to completely eradicate HHV-8. Consequently, treatment focuses on stopping progression, tumor reduction, symptom relief, preservation of organ function, and alleviating psychological distress [37]. Individualized treatment plans are based on KS subtype, disease extent, progression rate, and patient symptoms [38]. The cornerstone of KS management remains combination antiretroviral therapy (cART) [37]. Treatment strategies may also include local therapies for confined disease or systemic options such as radiation and chemotherapy for advanced stages. Localized KS may be addressed with topical agents (alitretinoin 0.1% ointment, imiquimod 5% cream), surgery, cryotherapy, or laser ablation [39]. Decision-making factors include tumor growth rate, spread and quantity of lesions, patient’s HIV viral load and CD4 + T-cell count, overall health status, and potential interactions between medications [40]. Surgical intervention is limited by recurrence risks and potential functional impairments from repeated procedures, and is not recommended for extensive lesions [41]. Advanced or symptomatic visceral KS, especially with extensive skin involvement or edema, often necessitates systemic chemotherapy in addition to cART. Cytotoxic chemotherapy is the standard of care for classic KS. Chemotherapy is also necessary in instances of immune reconstitution inflammatory syndrome [38]. Pegylated liposomal doxorubicin and liposomal daunorubicin are first line treatments in the case of systemic chemotherapy [38].

KS typically presents as a chronic and indolent malignancy among SOTR. A strategic approach in managing these patients involves switching to an mTOR inhibitor to decrease immunosuppression, mitigating the risk of KS progression. Complete response (CR) to treatment in non-visceral KS is approximately 53%, contrasting with lower CR rate of 27% in visceral cases. Prognosis is relatively favorable, with survival rates at 5 years ranging from 69 to 82%, and at 10 years, approximately 64%. Mortality is mainly due to infections, organ rejection, or KS progression [42].

Prognosis in KS is significantly influenced by the specific clinical manifestations and degree of severity. The most reliable prognostic indicator for KS is often its clinical classification [43]. For classic KS, prognosis seems to align with the level of immunosuppression and advanced age. Locally aggressive KS has a moderate prognosis, with a 3-year survival rate around 64% noted in African populations. For generalized KS, prevalent in AIDS-associated KS, the 3-year survival rate drops significantly to nearly 0% without intervention [30]. Relative survival rates for KS show significant racial disparities. White patients have the highest survival rates at 1, 3, and 5 years (84.26%, 77.79%, and 74.79%, respectively), whereas Black patients have the lowest (71.50%, 61.37%, and 57.38%). Asian American and Pacific Islander (AAPI) and American Indian and Alaska Native (AIAN) patients had intermediate survival rates. Black patients were shown to develop primary KS tumors at younger ages and were more likely to have later-stage tumors at presentation compared to other races. Cause-specific death rates were higher among Blacks (39.28%) and AIAN (35.38%), compared to Whites (23.15%) and AAPI (21.63%) [30]. These statistics highlight the considerable racial disparities in KS survival and progression.

Regarding mortality rate, there is concerning trend in Black KS patients. The hazard ratio for all-cause mortality in this population increased from 1.1 during 1981–1995 to 1.55 in 1996–2013 when compared to White patients [22, 30]. This suggests that disparities in KS incidence and outcomes may be attributed to differential adherence to HAART therapy. Black patients demonstrate lower HAART adherence and successful outcomes than Whites, potentially increasing HIV and HHV-8 co-infection rates [24, 30]. Moreover, the findings from Magi et al. indicate this pattern persisted into 2018, demonstrating that Blacks in the U.S. still bear a significantly elevated burden of KS. Additionally, a Puerto Rican HIV/AIDS cohort study reported a decline in AIDS-related cancers, including KS, yet incidence rates remained significantly higher than the general population, despite widespread cART use for 15 years [44].

These findings emphasize the enduring disparities that exist among POC, underscoring the ongoing need for targeted interventions and healthcare initiatives to address these challenges, particularly in the Black population.

Discussion

The review reveals pronounced disparities in presentation and treatment of DFSP and KS among POC, calling for culturally sensitive diagnostic and therapeutic strategies.

While POC are often classified as having skin phototypes IV to VI, it is important to recognize that their skin tones can range across the full spectrum of phototypes [45]. Notably, skin examination and sun protection practices vary among ethnic groups. Whites and Hispanics are more inclined to use sunscreen than Blacks [46]. Moreover, Whites tend to conduct skin self-examinations more frequently than Hispanics, and Blacks are less likely to seek dermatologic consultation [47]. Notably, a study found that Blacks who experienced severe sunburns were seven times less likely to use sunscreen compared to similarly affected White individuals [48].

Despite evidence of UV exposure contributing to increased skin cancer risk in Blacks, sun protection practices in this group remain underdiscussed. Analysis of the 1992 National Health Interview Survey by Hall and Rogers showed that while 6% of Black respondents reported high sunlight sensitivity, only 53% reported likely use of protective measures like clothing, sunscreens, or shade [49]. Factors such as higher education, younger age, and sunburn history appear to encourage sunscreen use. Additionally, Buster et al. found that Blacks perceive cancer risk as low and demonstrate limited awareness of lifestyle’s role in cancer risk [50]. Blacks and Hispanics also had a tendency to equate skin cancer with physical symptoms such as pain, and believed that little could be done for prevention. Regular skin examinations, crucial for early detection of skin cancer, were also less valued among these groups [50]. This underestimation of risk and the resultant insufficient sun protection practices can have serious implications for DFSP and KS in POC. These types of cancers require early detection for effective treatment, highlighting the need for increased awareness and education regarding sun protection and skin cancer risks in POC.

Patient education can be improved through provider education and counseling. Minority patients have been shown to be responsive to education about skin examinations, yet they often receive less counseling on this matter [51, 52]. Furthermore, past public awareness campaigns have largely neglected education on all skin types. Although these campaigns typically stress the role of sunlight in skin cancer development, they address the occurrence of skin cancers in sun-protected areas less frequently, a scenario more prevalent in POC [53].

Disproportionately higher incidence and severity of DFSP in Blacks necessitates a revaluation of current diagnostic and therapeutic strategies [5]. The frequent misdiagnosis of DFSP as keloids among Blacks is concerning as it suggests a gap in clinical recognition, likely contributing to larger and more advanced tumors at the time of diagnosis within this group [16]. Dermatoscopy complements clinical diagnosis, and the dermatoscopic features of DFSP in Blacks (pigmented network and pink background, telangiectasia, erythematous dome-shaped papillary outgrowths, and brown ill-defined areas) should be emphasized in training and practice to improve early detection and management [20]. Currently, few resources provide clinical images of patients with higher Fitzpatrick skin types [54, 55]. Access to such clinical images is crucial for improving diagnostic accuracy in POC. Dermatology residency training is crucial for developing diagnostic pattern recognition skills, yet over 30% of chief residents and program directors report a lack of focused didactic sessions on POC [56]. Only about a quarter of programs have lectures from experts in this area. Moreover, the disparities in treatment for DFSP, with Blacks more likely to receive surgery and radiation rather than surgery alone, raises questions about access to optimal care [8]. The preference for MMS over WLE in White, female, and higher-income patients points to potential biases in treatment offerings for POC, which may contribute to poorer outcomes in Blacks.

Epidemiological trends in KS, particularly the decreased survival rate, and increased incidence and mortality in Black males in the southern U.S., point to social and healthcare-related factors influencing disease outcomes [29]. The interplay of SES, access to healthcare, HIV testing, and HAART compliance are important in understanding these disparities. Studies have shown that African Americans are less likely to comply with and respond successfully to HAART than non-Hispanic White patients [26, 57]. This disparity potentially leads to increased rates of HIV and HHV-8 co-infections among Blacks. The difficulty in diagnosing KS in POC, particularly due to the challenge of visually identifying the characteristic violaceous hues on darker skin, emphasizes the need for improved diagnostic protocols and increased awareness among providers. Variations in KS treatment efficacy and the notable rise in KS among Black males highlight the necessity of addressing the social determinants of health that contribute to these disparities. Efforts to enhance outreach and education should involve collaboration with influential figures in local communities, including those in medical, business, and religious sectors. For young, non-Hispanic Black men in the Southern U.S.—a group significantly affected by outcome disparities—strategies such as effective HIV prevention, strategically located Syringe Services Programs, early and accurate HIV diagnosis, and improved treatment access are vital to address the health challenges faced by this subpopulation [27, 58]. While current treatments, such as antiretroviral therapy and chemotherapy, are effective, their accessibility and efficacy can vary significantly across different racial and ethnic groups. Table 1

This review demonstrates the need for more inclusive research that encompasses diverse populations to ensure that the findings are generalizable across all racial and ethnic groups. Increased representation of POC in future research is paramount to uncover the nuances in the presentation and progression of skin cancers like DFSP and KS in these populations. Clinically, there is a pressing need for training and educational programs that focus on the distinctive presentations of skin cancers in POC. Enhanced awareness and diagnostic accuracy are crucial for early detection and treatment, which can significantly improve patient outcomes. Moreover, to mitigate disparities in skin cancer outcomes, it is imperative to address systemic barriers that impede equal access to advanced treatments, and provide individualized care for POC. Table 2

Conclusion

A review of the current literature on DFSP and KS in POC revealed significant disparities in the presentation, diagnosis, and treatment of these cancers across different racial and ethnic groups. There is a pressing need for increased awareness and education about sun protection and skin cancer risks in POC, especially considering their varied skin phototypes and the common underestimation of risk. The frequent misdiagnosis of conditions like DFSP as keloids in Black patients, and the challenge in visually identifying KS on darker skin, highlights gaps in clinical knowledge and the crucial need for improved diagnostic protocols. Disparities in treatment access, along with socioeconomic and healthcare-related factors, contribute to worse health outcomes in these populations. This underscores the importance of more inclusive research, enhanced training and education in dermatology, and addressing systemic healthcare disparities to improve patient outcomes for DFSP and KS in POC. 

Table 1 DFSP features in Caucasians and people of color
Full size table
Table 2 KS features in Caucasians and people of color
Full size table