Malignant histiocytosis of the intestine: the early histological lesion.

A histological study of peroral jejunal biopsies and resection specimens from patients with malignant histiocytosis of the intestine (MHI) has revealed characteristic lesions consisting of intramucosal histiocytic aggregations which invade surface and crypt epithelium. These lesions are found in 'uninvolved' jejunal mucosa in the presence of obvious tumour elsewhere and also in peroral jejunal biopsies many years earlier than the diagnosis of MHI. It is suggested that they represent the early lesion and their recognition in peroral jejunal biopsies could be important in improving the prognosis of the disease.