Alopecia
Results from a limited number of studies suggest that tretinoin
may be used alone or in combination with minoxidil for
treating alopecia.104-107 Topical tretinoin may help promote hair
growth through effects on epithelial cell proliferation and differentiation,
as well as vascular proliferation.108 In addition, topical
tretinoin may enhance the absorption of minoxidil, which is
known to stimulate hair regrowth.106,107
Warts/Nevoid Hyperkeratosis
Case studies have evaluated topical tretinoin for warts or nevoid
hyperkeratosis, with equivocal findings.109-112 Topical tretinoin
may be effective in the treatment of nevoid hyperkeratosis due
to its ability to modulate abnormal follicular keratinization.10
Hyperkeratosis Follicularis et Parafollicularis (Kyrle’s Disease)/ Keratosis Follicularis (Darier’s Disease)
Whereas results of a case study suggest that topical tretinoin
use to treat hyperkeratosis follicularis was limited due to AEs,
other studies suggest that topical tretinoin may be useful for
treating Darier’s disease.113-116 The effectiveness of topical tretinoin
in Kyrle’s disease may be due to its effect on epidermal
proliferation and keratinization.116
Porokeratosis
Three case studies suggest that topical tretinoin may benefit
patients with porokeratosis.117-119 The effectiveness of topical
tretinoin in treating porokeratosis may be due to its ability to
modulate abnormal follicular keratinization.118
Psoriasis
One case study showed the effectiveness of sequential application
of topical tretinoin (0.3%) and a corticosteroid for treating corticosteroid-
resistant plaque-type psoriasis.120 Another study showed that
adding topical tretinoin to a topical corticosteroid for treating psoriasis
partially ameliorates corticosteroid-induced epidermal atrophy.121
Effectiveness in psoriasis may be attributed to the ability of topical
tretinoin to modulate many of the pathogenic factors thought to be
responsible for psoriasis; tretinoin is antiproliferative, normalizes
abnormal keratinocyte differentiation, and is antiinflammatory.
Acanthosis Nigricans
One report showed that a combination of 12% ammonium
lactate cream and 0.05% tretinoin cream improved acanthosis
nigricans associated with obesity. Case studies showed that
daily topical tretinoin was effective in improving both clinical
and histological measures of acanthosis nigricans.122,123 The
action of topical tretinoin in acanthosis nigricans may be attributed
to its keratolytic effects.123
Rosacea
Randomized, double-blind data suggest that low-dose topical
tretinon may be useful for treating rosacea.124 The effects of topical tretinoin in rosacea may be due to its inhibition of skin
metalloproteinases and its down-regulation of toll-like receptor
2, which is reported to be overexpressed on the epidermis
of patients with rosacea.124-126
Nevus Comedonicus
Case studies of nevus comedonicus on the face, chest, and neck
have demonstrated an extrusion of comedones and a reduction
in lesion size in response to treatment with retinoic acid alone or
topical tretinoin in combination with a 1450-nm diode laser.127,128
Keratosis Pilaris
A case report of a woman with keratosis pilaris atrophicans
faciei showed that 1 month of topical tretinoin treatment was
effective in decreasing erythema and follicular hyperkeratosis.
129 Effectiveness for this condition may be expected given
the keratolytic effects of tretinoin.
Antilice Agent
Due to its inhibitory effects on glutathione-S-transferase, topical
tretinoin has been recommended as an antilice agent to
augment the effects of topical antilice agents including permethrin,
pyrethrins, and dichlorodiphenyltrichloroethane (DDT).130
Trichoepitheliomas
Combination imiquimod and topical tretinoin may be effective
as a nonscarring treatment for trichoepitheliomas.131
Eruptive Milia
A case study demonstrated rapid improvement of eruptive milia
with topical tretinoin treatment.132
Lichen Planus
A case study showed that application of a tretinoin and triamcinolone
combination was a successful treatment for lichen
planus.133 The effects of topical tretinoin on lichen planus may
be due to increased epidermal proliferation and collagenesis.134
Reactive Perforating Collagenosis
One case study demonstrated the effectiveness of tretinoin
cream (0.1%) for reducing the total number of reactive perforating
collagenosis lesions.135
Keratinizing Dermatoses
Multicenter trial data showed that topical tretinoin (0.1%) was
effective in treating keratinizing dermatoses, including lamellar
ichthyosis and ichthyosis vulgaris.136 It is unclear whether the keratolytic
properties of tretinoin or its ability to normalize keratinocyte
differentiation was responsible for the noted improvement.
Intrinsic/Chronological Aging
One clinical trial found that tretinoin cream applied once daily
for 9 months in older women (aged 68-79 years) showed marked
