Dermatology Online Journal

Cutaneous cancers in Calabar, Southern Nigeria
Maurice E Asuquo¹, Godwin Ebughe²
Dermatology Online Journal 15 (4): 11

1. Department of Surgery
2. Department of Pathology
University of Calabar Teaching Hospital, Calabar, Nigeria

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Abstract

Globally, cutaneous cancers are among the most common form of cancer. Among Africans, there are significant differences in the types of skin cancer compared to those documented in patients from other countries. We evaluated all the patients with a histological diagnosis of skin cancer presenting to the University of Calabar Teaching Hospital from January 2005 through December 2006. Twenty-nine patients (18 males and 11 females) with skin cancer were identified and these accounted for 8.0 percent of total malignancies. Their ages ranged from 16 to 70 years (mean 43.5 years). Kaposi sarcoma (KS) was the most common skin cancer. Kaposi sarcoma associated with HIV represented 81.8 percent of KS cases found. Squamous cell carcinoma (SCC) ranked second and malignant melanoma third. Of the skin cancers in our series, the most common site was the lower limb (55.2%), followed by the head and neck (24%). The 4 albinos accounted for 13.8 percent of the skin cancers found. Immunosuppression (KS), chronic ulcer, inflammation, albinism, and solar radiation were identified risk factors. Public education strategies on prevention, with an emphasis on early identification and surgical treatment of skin cancers are urged. In addition, treatment of and close observation of chronic ulcers are recommended.

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Introduction

Malignant skin tumors are among the most common form of cancer [1]. Skin cancers are the most frequently diagnosed cancer in the United States; of these, approximately 80 percent are basal cell carcinoma (BCC) and 20 percent are squamous cell carcinoma (SCC), the second most common skin cancer [2]. The incidence of skin cancer among the darker pigmented peoples of other areas of the world is much lower. In Africa, several studies reveal the preponderance of SCC [1, 2, 3]. Among Africans, there are significant differences in the pattern of skin cancer. In Tanzania, KS is the second most common dermatological malignancy, whereas melanoma is the second most common in Northern Nigeria [3, 5]. Plantar melanomas are relatively common in sub-Saharan Africa but much less common among Africans-Americans [6]. Sun exposure is the major etiological factor in whites, whereas the non-solar factors of chronic ulceration and inflammation appear to be the leading risk factors in blacks [3, 4]. Albinism is a risk factor for skin cancer and SCC is the most common dermatological malignancy among African albinos [7, 8]. We present this study that seeks to evaluate the current pattern of skin cancer and risk factors in our region.

Material and Methods

All the patients with a histological diagnosis of cutaneous malignancy who presented to the University of Calabar Teaching Hospital, Calabar, Nigeria, from January 2005 through December 2006, were evaluated as part of the ongoing prospective study of skin cancer.

Results

Figure 1
Figure 1. Squamous cell carcinoma

Twenty-nine cutaneous malignancies were reported in the period studied. It comprised 8.0 percent of all histological diagnosed cancer in Calabar in the same period. The ages ranged from 16 to 70 years (mean 43.5 years). Males comprised 18 patients (62%) and 11 (38%) were females; (M:F = 1.6:1). The four albinos (SCC-2, BCC-1, and melanoma-1) accounted for 13.8 percent of the skin cancer found (Fig. 1); all patients were of African heritage.

Figure 2
Figure 2. Kaposi sarcoma affecting the eyelids and nose

Table 1 shows the type/site distribution of cutaneous cancers. The most common malignancy was KS, which afflicted 11 (38.8%) patients. Nine of these patients (81.8%) were HIV positive (Fig. 2). Squamous cell carcinoma, which ranked as the second most common skin malignancy, affected 10 (34.5%) patients. In six patients, SCC arose within a chronic ulcer (Marjolin ulcer). Of these chronic wounds, four resulted from trauma (two road traffic accidents and two falls) and one case each from chronic osteomyelitis and an old scar. Squamous cell carcinoma in four patients did not arise from chronic ulcer (non-Marjolin). These patients included two albinos and two females with vulvar tumors. Melanoma afflicted four patients (13.8%) including an albino with an upper limb tumor. The others were darkly pigmented patients with plantar melanomas. The only BCC was found in an albino. Two metastatic skin cancers presented as skin nodules, SCC of the neck and adenocarcinoma of the chest wall (6.9%). Malignant adnexal tumour (eccrine) affected one patient.

Table 1 shows the site distribution of cutaneous cancers. The lower limb was the most common site found in 16 (55.2%) darkly pigmented patients. The head and neck ranked second in seven (24%) patients, three were albinos, (two SCC, one BCC).

Generally, the outcome was poor because most patients presented late and this precluded curative treatment. However, two patients with KS (not related to HIV) showed clinical improvement (regression of nodules) with cytotoxic chemotherapy (vincristine); follow-up was for 10 and 12 months. The outcome was good in the only patient with superficial spreading melanoma (SSM) after wide excision; follow-up was for 12 months with no clinical evidence of recurrence or metastasis. Two patients with BCC and malignant adnexal tumor (eccrine porocarcinoma) had excisions; the outcomes were satisfactory. There has been no clinical evidence of recurrence after 12 and 9 months of follow up respectively.

Discussion

Twenty-nine patients (25 blacks and 4 albinos) with cutaneous malignancies comprised 8.0 percent of all malignancies with histological diagnosis in Calabar; in a previous study it was 10 percent of total malignancies [9]. This was comparable with 12.3 percent in Zaria [10] and 12.7 percent in Kano [5]. The relative frequency of cutaneous cancer is much lower than in the caucasians in Europe, North America, and Australia [1]. Lower levels of protective cutaneous melanin in caucasians render them more vulnerable to carcinogenesis from solar radiation [11].

Kaposi sarcoma was the most prevalent cutaneous malignancy in our region and comprised 38.8 percent of cutaneous cancers. In a previous study in this center, it ranked second (27%) after SCC (36.5%) [12]. The rise is likely due to an increase in the HIV-related KS, which accounted for 81.8 percent of these tumors. Since the emergence of HIV infection, there has been a steady increase in the prevalence of KS worldwide [13]. In Nigeria, with an adult seropositivity of 5.8 percent, this disease has become a major cause of morbidity and mortality [14]. In Zimbabwe, there has been a significant rise in skin cancer because of the increased number of HIV-related KS cases [15]. Successful prevention and treatment of HIV infection should reduce the prevalence of this tumor.

Squamous cell carcinoma ranked second at 34.5 percent (Marjolin six, non-Marjolin four). Numerous reports from Nigeria and other parts of Africa document SCC secondary to chronic ulcers as the major risk factor [3, 4]. This contrasts with light-skinned people in whom sun exposure is the major etiological factor [1]. Traumatic injuries are preventable, but chronic ulcers are common in the developing world. If poorly managed, as in the patients we observed, the ulcers may undergo malignant transformation, hence the need for prompt and proper medical and surgical management of chronic ulcers.

The four albinos accounted for 13.8 percent of the skin cancers. A similar study in Port Harcourt, southern Nigeria, reported 16.7 percent [16]. The head was the site commonly affected in three patients, (two SCC and one BCC) and the upper limb in the albino with melanoma. The occurrence of these tumors in sun-exposed parts of the body highlights the role of solar radiation as a risk factor in skin cancer in albinos. In contrast, the head was not affected in any darkly pigmented patient, which highlights the effectiveness of protection against solar radiation provided by melanin. There was just one case of BCC in this report, which contrasts sharply with BCC incidence in caucasians, in whom 70 to 80 percent of skin cancers are BCC [1].

Melanomas are the most lethal of the cutaneous malignancies in our series. It was the third most prevalent tumor and affected four patients (13.4%). Three out of the four patients presented with plantar melanoma, which is similar in other black populations in Africa and in diaspora. This has prompted the speculation of trauma as an etiological factor, as opposed to solar radiation, which is a major culprit in whites [1, 6].

In conclusion, immunosuppression (KS), chronic ulcers and inflammation, albinism, and solar radiation were identified as risk factors for skin cancer. The implementation of public education strategies concerning prevention as well as medical and surgical evaluation of chronic ulcers would improve prognosis and reduce health care costs associated with cutaneous cancers.

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