With the increasing use of anti-tumor necrosis factor α (anti-TNF) biologic 
drugs to treat autoimmune diseases, an expanding array of adverse reactions is 
emerging. Anti-TNF drug-induced alopecia is a less well-known side effect of 
this class of drugs. The aim of this study was to define the clinical and 
histopathological features of alopecia arising in the setting of anti-TNF 
therapy. Clinical and histopathological features of 3 patients who developed 
scalp alopecia during anti-TNF treatment were examined. Two of the 3 patients 
also developed psoriasiform lesions outside the scalp, and biopsies from both 
scalp and nonscalp sites were reviewed. Clinically, each patient had large scaly 
patches associated with the scalp alopecia. All scalp biopsies revealed 
psoriasiform epidermal features and alopecia areata-like dermal changes. 
Epidermal changes included acanthosis and confluent parakeratosis with 
neutrophils and frank pustules. Dermal changes included markedly increased 
catagen/telogen and miniaturized hairs and peribulbar lymphocytic inflammation. 
Numerous plasma cells and eosinophils were present in all cases. Biopsies from 
the nonscalp lesions showed psoriasiform changes and prominent eosinophils and 
plasma cells. Two patients showed significant improvement of the alopecia with 
topical treatment only. In conclusion, anti-TNF therapy-related alopecia may 
closely mimic psoriatic alopecia and alopecia areata but can be histologically 
distinguished from alopecia areata by epidermal psoriasiform changes and dermal 
plasma cells and from primary psoriasis by the presence of plasma cells and 
eosinophils. A correct diagnosis can enable effective treatment and, in some 
cases, allow anti-TNF therapy to continue.