Distribution of lysozyme (muramidase) and alpha 1-antichymotrypsin in normal and neoplastic epithelial tissues: a survey.

Lysozyme and alpha 1-antichymotrypsin are useful in differentiation of histiocytic tumours. Both enzymes, however, also can be expressed in epithelial tissues. In contrast to lysozyme, alpha 1-antichymotrypsin is more often found to be positive in non-histiocytic neoplasias. In general, the activity of parent tissue is retained in tumour cells. In malignant melanoma and in single cases of other epithelial tumours an activity of alpha 1-antichymotrypsin was found which could not be demonstrated in normal parent tissue and which may find its explanation in a dedifferentiation of tumour cells.