What is rosacea?

Rosacea Definition and Diagnostic Criteria

Rosacea is a chronic inflammatory skin disease primarily affecting the central face, characterized by two independently diagnostic features: persistent centrofacial erythema with periodic intensification by trigger factors, or phymatous changes. 1

Diagnostic Features

• Persistent centrofacial erythema with periodic intensification by trigger factors is considered a minimum diagnostic feature of rosacea 1
• Phymatous changes (thickening of skin due to hyperplasia of sebaceous glands) are independently diagnostic of rosacea 1
• The following features alone are NOT diagnostic of rosacea:
  • Flushing 1
  • Telangiectasia 1
  • Inflammatory papules/pustules 1

Major Features

• Flushing/transient erythema - characterized by intensity, frequency, duration, area involved, and associated symptoms 1
• Persistent erythema - assessed by intensity and extent 1
• Inflammatory papules/pustules - evaluated by number of lesions and extent of facial involvement 1
• Telangiectasia - assessed by vessel size and extent of involvement 1
• Phymatous changes - characterized by inflammation, cutaneous thickening, deformation, and sites involved 1
• Ocular manifestations - including blepharitis, conjunctivitis, and keratitis 1

Minor Features

• Burning sensation 1
• Stinging sensation 1
• Edema 1
• Dry sensation 1

Pathophysiology

• Rosacea involves dysregulation of both innate and adaptive immune systems 1
• Key pathophysiological mechanisms include:
  • Increased levels of antimicrobial peptides, neuropeptides, and nitric oxide radical species 1
  • Dysregulation of keratinocytes, endothelial cells, macrophages, mast cells, and dendritic cells 1
  • Involvement of T helper cells (Th1, Th17) and plasma cells 1
• Trigger factors such as Demodex mites and ultraviolet radiation may activate inflammatory pathways 1, 2

Epidemiology and Demographics

• Rosacea affects up to 10% of the world population 3
• More common in fair-skinned individuals aged 35-50 3
• Women are affected more frequently than men, though it can be more severe in men 3
• Challenging to diagnose in darker skin types (phototypes V and VI) as erythema and telangiectasia may not be visible 1

Classification Evolution

• Traditional classification included four subtypes: erythematotelangiectatic, papulopustular, phymatous, and ocular rosacea 1, 4
• Current approach has shifted from subtype-based to phenotype-based classification 2
• The phenotype-based approach addresses rosacea in a manner more consistent with the patient's individual experience 1

Diagnostic Challenges

• In patients with darker skin tones, diagnosis may require greater emphasis on hyperpigmentation and symptoms of irritation (burning and stinging) 1
• Ocular rosacea may present with blepharitis, meibomian gland dysfunction, and corneal involvement 1
• In children, ocular symptoms may precede cutaneous manifestations, leading to potential misdiagnosis 1
• Skin biopsy may be considered for diagnostic support in challenging cases 1

Clinical Course

• Rosacea is a chronic condition characterized by periods of exacerbation and remission 4
• Without treatment, severe staphylococcal blepharitis may lead to eyelash loss, eyelid scarring with trichiasis, and corneal scarring and neovascularization 1

The phenotype-based approach to rosacea diagnosis represents a significant advancement in clinical practice, allowing for more personalized assessment and treatment based on the specific manifestations present in each patient 2.