Seven patients with xeroderma pigmentosum were entered into a cancer chemoprevention study using isotretinoin: results indicate significant partial inhibition of new tumor formation during therapy and a marked increase in new tumor formation after therapy. Long-term therapy with low-dose isotretinoin is now being used for cancer chemoprevention in these patients. Suicidal ideation is a potential problem in patients with chronic disfiguring dermatoses, such as Darier's disease. Seven of 11 patients with Darier's disease had a history of suicidal thoughts, plans or attempts. In a control group of 11 patients with lamellar ichthyosis and similar disorders, 3 patients had suicidal thoughts or plans. One patient with multiple skin cancers developed an adverse drug reaction to fenretinide, a synthetic retinoid. The reaction included diarrhea, elevated liver function tests and a morbilliform skin eruption. Two patients with symptomatic, etretinate-resistant, Darier's disease were successfully treated with deep split-thickness skin excision using as electrosurgical unit. Healing was rapid and recurrence of disease has been minimal. A case of Darier's disease, well-controlled with etretinate, markedly worsened on two separate occasions after ingestion of lithium and improved after its discontinuation. Seven patients developed symptoms of severe depression during treatment with oral isotretinoin. All depressive symptoms resolved completely within 2 to 7 days after discontinuation of the drug.