Acquired Non‐Infective Disorders of the Pilosebaceous Unit

Abstract The presentation, aetiology and management of acquired superficial and deep disorders of the pilosebaceous units are discussed in this chapter. The chapter begins with discussion of external causes and systemic medications, including EGFR inhibitors, as causes of folliculitis. Infantile and adult eosinophilic folliculitis is subsequently explored, followed by actinic folliculitis which rounds up the discussion on the disorders affecting the superficial pilosebaceous unit. Disorders causing inflammation of the pilosebaceous gland below the level of the infundibulum are then discussed. The presentation, aetiology and management of pseudofolliculitis, necrotising lymphocytic folliculitis of the scalp margin, chronic non‐scarring folliculitis of the scalp, and disseminate and recurrent infundibulofolliculitis are covered. Discussion of Fordyce spots and sebaceous hyperplasia concludes the discussion.