Histopathological study of pigmented tumours and tumour-like skin lesions

ABSTRACT

This retrospective study included 85 cases of pigmented tumours and tumour-like lesions. The majority were benign tumours representing 65.9 percent while the malignant tumours constituted 34.1 percent. The benign pigmented tumours were melanocytic skin naevi [37.6 percent], lentigo simplex [1.2 percent], lentigo senilis [1.2 percent], dermatofibroma [5.9 percent] and seborrheic keratosis [20 percent]. The malignant tumours were malignant melanoma [12.9 percent] and pigmented basal cell carcinoma [21.1 percent]. The face represented the site of predilection of all the pigmented tumours [52.9 percent]. Melanocytic naevi were the only pigmented lesions in the first decade of life. The sixth and seventh decades of life represented the highest incidence for malignant melanoma and pigmented basal cell carcinoma. The histologic patterns of seborrheic keratosis included in this study were the acanthotic type [58.9 percent], the hypertrophic type [17.6 percent], the irritated type [17.6 percent] and mixed hypertrophic and reticulated type [5.9 percent]. Two types of malignant melanoma were included in this study, the nodular malignant melanoma [72.7 percent] and the acral lentiginous melanoma [27.3 percent]. The majority of cases of malignant melanoma showed combination of spindle and epithelioid cells [54.5 percent], while in 27.3 percent of cases, there was predominant epithelioid cells and in 18.2 percent, there was predominant spindle cells. The recurrent cases of malignant melanoma possessed predominant spindle cell element. While 54.5 percent of cases of malignant melanoma were Clark level III, 18.2 percent were clark level IV and 27.3 percent were difficult to be leveled as they were recurrent cases. The cases of pigmented basal cell carcinoma included in the study were the solid pattern [33.3 percent], the mixed solid and cystic patterns [38.9 percent] and the mixed sloid and adenoid-cystic patterns with pilar differentiation [27.8 percent]