Haematoporphyrin diacetate: a probe to distinguish malignant from normal tissue by selective fluorescence.

Haematoporphyrin diacetate has been synthesized and purified. Following introduction into mice bearing squamous-cell carcinomas it was found to produce a fluorescence of the tumour tissue which was much stronger than that of the surrounding normal tissue. Haematoporphyrin diacetate was also shown to be the major active component of the impure compound known as haematoporphyrin derivative which has been widely used in tumour fluorescence studies.