Rosacea (acne rosacea) is a common disorder of young and middle aged adults.  Children are rarely affected.

Aetiopathogenesis of rosacea is not clear. Several hypotheses have been documented in the literature and include potential roles for vascular abnormalities, dermal matrix degeneration, environmental factors, and microorganisms such as Demodex folliculorum and Helicobacter pylori.

Site:  Commonly occurs on the center of the face ( nose, forehead, cheeks, and chin)

Gross clinical presentation:  The lesion may present red macules, papules, and nodules, as well as pustules and telangiectases .

1. Telangiectatic:  Erythematous macules associated with strikingly dilated end blood vessels.

2.  Perioral-periocular dermatitis:  Papules and pustules around the mouth and eyes

3. Granulomatous: Characterized by tuberculoid granuloma.

4. Rhinophyma :  Enlargement of the nose due to proliferation of sebocytes in sebaceous glands . There is formation of infundibular cysts that rupture and elicit  granulomatous and fibrosing inflammation

5. Lupus miliaris disseminatus faciei :  Papular variant of granulomatous rosacea

Histopathologic features:

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There is a combination of various histopathological features:

Telangiectasia of superficial blood vessels;

Perivascular infiltrates of lymphocytes (mild to moderate in intensity) and, sometimes, plasma cells ;

Active pustular lesions show superficial folliculitis;

Older lesions show granulomatous perifolliculitis.

Demodex mites are noted (20-50% cases)

Well-circumscribed collections of epithelioid histiocytes, usually in peri-infundibular location ;

Granulomas surrounded usually by lymphocytes and, sometimes, plasma cells ;

Small collections of neutrophils in some granulomas ;

Caseous necrosis may be present within some granulomas 

Rhinophyma:  Sebaceous gland hypertrophy and scattered follicular plugging.

Visit: Granulomatous Reaction Pattern

Differential diagnosis:

Tuberculosis and other mycobacterial infections : Tuberculoid granulomas with caseous necrosis. The lesion is not infundibulocentric.

Bacterial infundibulitis &  Acne vulgaris