Aphthous stomatitis
Aphthous stomatitis (also termed recurrent aphthous stomatitis, RAS, and commonly called "canker sores") is a very common cause of oral ulceration. 10–25% of the general population have this non-contagious condition. Three types of aphthous stomatitis exists based on their appearance, namely minor, major and herpetiform major aphthous ulceration. Minor aphthous ulceration is the most common type, presenting with 1–6 small (2-4mm diameter), round/oval ulcers with a yellow-grey color and an erythematous (red) "halo". These ulcers heal with no permanent scarring in about 7–10 days. Ulcers recur at intervals of about 1–4 months. Major aphthous ulceration is less common than the minor type, but produces more severe lesions and symptoms. Major aphthous ulceration presents with larger (>1 cm diameter) ulcers that take much longer to heal (10–40 days) and may leave scarring. The minor and major subtypes of aphthous stomatitis usually produce lesions on the non-keratinized oral mucosa (i.e. the inside of the cheeks, lips, underneath the tongue and the floor of mouth), but less commonly major aphthous ulcers may occur in other parts of the mouth on keratinized mucosal surfaces. The least common type is herpetiform ulceration, so named because the condition resembles primary herpetic gingivostomatitis. Herpetiform ulcers begin as small blisters (vesicles) which break down into 2-3mm sized ulcers. Herpetiform ulcers appear in "crops" sometimes hundreds in number, which can coalesce to form larger areas of ulceration.
It is also useful as maintenance therapy for people who have responded to their initial treatment, reducing the prolonged use of antibiotics for acne. Leukemia
Tretinoin is used to induce remission in people with acute promyelocytic leukemia who have a mutation (the t(15;17) translocation 160 and/or the presence of the PML/RARα gene) and who do not respond to anthracyclines or cannot take that class of drug. It is not used for maintenance therapy.The evidence is very uncertain about the effect of tretinoin in addition to chemotherapy for patients with an acute myeloid leukemia on diarrhoea, nausea/vomiting and heart-related toxicity grades III/IV. Furthermore, tretinoin in addition to chemotherapy probably results in little to no difference in the mortality, relapse, progress, mortality during the trial and infections grade III/IV. Photoaging
Photoaging is premature skin aging resulting from prolonged and repeated exposure to solar radiation. Features of photoaging include fine and coarse wrinkles, change in skin pigmentation, and loss of elasticity. In human skin, topical retinoids increase collagen production, induce epidermal hyperplasia, and decrease keratinocyte and melanocyte atypia. Topical tretinoin is the most extensively investigated retinoid therapy for photoaging. Topical tretinoin can be used for mild to severe photoaging in people of all skin types. Several weeks or months of use are typically required before improvement is appreciated. The benefits of topical tretinoin are lost upon discontinuation. Although it has only been studied for a duration of two years, it may be continued indefinitely.