Kaposi's sarcoma: histopathological study of 159 cases from Malawi.

The histological features of 168 lesions of Kaposi's sarcoma from 159 patients in Malawi, where the disease is commoner than elsewhere, were characteristic. All showed well-developed areas of tumour and could be grouped fairly readily into those with a mixed pattern, a predominantly spindle cell pattern, and an anaplastic group, though intermediate patterns were seen. Hyaline bodies were present in nearly all tumours of skin. The cell of origin of Kaposi's sarcoma is uncertain and possibly has multipotential capabilities. Differential diagnosis may be difficult. Clinically the lesion may be confused with granuloma pyogenicum and may also be like it histologically. The presence of hyaline bodies and deposits of haemosiderin indicate Kaposi's sarcoma. The spindle cell predominant type may be confused with leiomyoma, leiomyosarcoma, or fibrosarcoma. The presence of hyaline bodies and the formation of vascular channels between spindle cells point to a diagnosis of Kaposi's sarcoma.