1. Six patients with mycosis fungoides, resistant to x-radiation, have been treated with nitrogen mustard.
2. Each patient showed a striking immediate response to the drug.
3. The extent of the remissions of the disease process, during the period of study (from 4 to 7 months), varied with the nature of the lesions and the biopsy findings: (a) Three patients with histories of prolonged premycotic stages and reticulo-endothelial cell hyperplasia on biopsy showed an excellent response to the drug. (b) One patient with a history of prolonged premycotic stage and biopsy findings of a dense polymorphic infiltrate, but with sparse numbers of reticulo-endothelial cells showed a partial response to treatment. (c) Two patients whose disease was of short duration with early nodule formation and ulceration with biopsy findings of rather few endothelial cells among the infiltrate showed rapid recurrences and progression of the disease.
4. Nitrogen mustard is an effective agent in the palliative treatment of mycosis fungoides.
5. It is suggested that the point of attack of the nitrogen mustard is on the neoplastic cell arising from the reticulo-endothelial system.
6. The response of mycosis fungoides to nitrogen mustard presents additional evidence of the neoplastic nature of the disease.