Lichen Simplex Chronicus Positive for C5b-9/MAC, IgD, and C3c Due to Recurrent Bacterial Hair Follicular Unit Infection

November 2020 in “ Our Dermatology Online ”

Ana Maria Abreu Velez, Billie L. Jackson, Michael S. Howard

Lichen simplex chronicus chronic bacterial folliculitis sebaceous glands hair follicles IgD C3c HLA-ABC C5b-9/MAC direct immunofluorescence immunohistochemistry LSC DIF IHC

TLDR Chronic bacterial infections of hair follicles can cause ongoing skin inflammation.

In 2020, a case study was conducted on a 20-year-old female suffering from recurrent inflammatory itchy papules, pustules, and thickened plaques on her arms for over six months. The patient's skin biopsies revealed Lichen simplex chronicus (LSC), a condition often caused by chronic scratching, and Gram positive bacteria in the sebaceous glands. The hair follicles tested positive for IgD and C3c, and IHC positivity with HLA-ABC and C5b-9/MAC was observed in the same areas. The study concluded that chronic bacterial folliculitis could lead to a cycle of chronic inflammation. The study also highlighted the importance of using direct immunofluorescence (DIF) and immunohistochemistry (IHC) in addition to H&E review in cases of LSC with unclear causes.

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