Villous atrophy with crypt hyperplasia in malignant histiocytosis of the nose.

Intestinal changes, mainly in the jejunum, were investigated in 13 cases of malignant histiocytosis at necropsy and who had presented as lethal midline granuloma. Villous atrophy with crypt hyperplasia was observed in all cases, and a proliferation of atypical histiocytes was observed in seven cases. In the remaining cases, histiocytes with normal morphology increased in number. These findings showed that a prolonged abnormal proliferation of histiocytes was present in the small intestine of these cases concurrently with the nasal lesions.