Fig. 9.2 Acne. A Open and closed comedones and several inflammatory papules. B Papulopustules and scarring. C Follicular rupture and inflammation. A, Courtesy Kalman Watsky, MD; B, Courtesy, Andrew Zaenglein, MD and Diane Thiboutot, MD. A,B, From Bolognia JL, Schaffer JV, Duncan KO, Ko CJ. Dermatology Essentials, 1e. Philadelphia: Saunders, 2014, with permission.
Sequelae include scarring and postinflammatory pigmentary changes (see Fig. 9.2)
Rosacea
Most commonly affects the face (Fig. 9.3); rarely scalp, chest
Fig. 9.3 Rosacea. A–C Papulopustular form. Lymphocytes surround follicles. D,E Granulomatous rosacea (perifollicular granulomas). A, Courtesy, Kalman Watsky, MD; B,D, Courtesy, Yale Dermatology Residents’ Slide Collection. B,D, From From Bolognia JB, Jorizzo JL, Rapini RP. Dermatology, 2e. London: Saunders, 2008, with permission.
Papulopustular form and granulomatous variant are folliculo-centric
Histopathology:
Perifollicular and perivascular lymphocytes +/− histiocytes
Dilated vessels
Folliculitis
Folliculitis is inflammation of hair follicles and can be superficial or deep, infectious (Fig. 9.4) or non-infectious (Figs 9.5, 9.6)
Fig. 9.4 Infectious folliculitis. A,B Bacterial (Staphylococcus aureus) folliculitis. Clumps of bacteria are present in an inflamed follicle. C,D Fungal folliculitis. Around the hair shaft, there are hyphae cut in cross-section (arrow). In addition to erythematous papules, there are plaques with annular scale. E,F Viral (herpes simplex virus) folliculitis. There is acantholysis with multinucleate cells. G,H Demodex folliculitis. Demodex mites are located in the dermis with surrounding inflammation. A, Courtesy, Julie V Schaffer, MD; E, Courtesy, Yale Dermatology Residents’ Slide Collection; G, Courtesy, Kalman Watsky, MD. A, From Bolognia JL, Schaffer JV, Duncan KO, Ko CJ. Dermatology Essentials, 1e. Philadelphia: Saunders, 2014, with permission.
