Clinicopathological Features of Malignant Melanoma of the Skin Among Patients Seen at Kenyatta National Hospital

Abstract

Background: Malignant melanoma (MM) originates in the pigment-producing melanocytes of the skin. Although once considered uncommon worldwide, the annual incidence has increased over the last few decades. It is curable when diagnosed in its early stages, but poses a major challenge to the physician in advanced stages and can be fatal. While it is not the most common of the skin cancers, it causes the most deaths. There is paucity of data regarding the clinical and pathological characteristics of MM in Kenya. Objective: The aim of this study was to describe the clinical and pathological characteristics of MM of the skin among patients at the Kenyatta National Hospital (KNH). Materials and methods: This was a cross-sectional descriptive study carried out over 6 months at Kenyatta National Hospital (KNH) surgical wards and histopathology laboratory. Patients with skin lesions confirmed on histology of incisional biopsy, to be MM were enrolled consecutively from the: Plastic Surgery Ward, General Surgery Wards, Surgical Out-Patient Clinic and Accident and Emergency Department. Data collected included gender, age at diagnosis, clinical examination findings, histopathologic subtype, stage of the disease clinically and pathologically, Serum Lactate Dehydrogenase (LDH) level and radiological tests. Data collected was checked for completeness, entered into MS Excel, cleaned and analyzed by the use of Statistical Package for Social Science (SPSS) version 20. Demographic data was presented by use of frequencies and percentages, as well as means and standard deviations. Categorical variables were analyzed as proportions. Fisher-Freeman-Halton exact test was used to test associations. All results were considered significant at p < 0.05. The data was presented in form of tables, bar charts and pie charts. Results: The results of this study show that the most common histopathologic subtype of MM in the Kenyan population presenting at the Kenyatta National Hospital for treatment is acral lentiginous melanoma (ALM) followed by nodular melanoma. The female population is affected to a larger degree than the male population, with a male: female ratio of 1:2.4. The mean age was 62 years, and the peak incidence was in the 6th and 7th decade of life. The commonest symptoms were swelling and ulceration. The anatomical location of 95.8% of the lesions, was in the lower limb especially on the foot, the left being more frequently affected than the right. Majority of the patients presented with stage II disease with a higher number of them being female, followed by stage III disease. In this study 58.3% of the patients presented with T4b (Tumour) disease with ulceration being prevalent across all T size stages. 70.8% of the study population had disease with a Breslow thickness greater than 4mm. 54.2% of the patients presented with symptoms of 1-3 years. Conclusion: This study has demonstrated that the most common molecular subtype of MM across all age groups is ALM, followed by nodular melanoma. Majority of the patients presented with late stage disease. The poor prognosis in black patients in Kenya is the result of delayed presentation with thick primary lesions and advanced disease.