The histopathology, direct immunofluorescence and immunoperoxidase staining in the distinction between lichen plano-pilaris and central centrifugal cicatricial alopecia

Thesis (Sc.D.)--Boston UniversityLichen planopilaris (LPP) and central centrifugal cicatricial alopecia (CCCA) are lymphocytic scarring alopecias. They share overlapping clinical and histopathologic findings. The goal of this dissertation has been to fmd reliably distinguishing features between these two conditions. Toward this goal, three different studies were conducted. Study 1 was a retrospective cross-sectional data analytic review of histologic features from patients identified by diagnosis of LPP or CCCA. Horizontal sections at level of the infundibulum, isthmus and inferior from scalp biopsies of 24 patients (19 CCCA and 5 LPP) were analyzed. The findings of unaffected follicular units, retained sebaceous glands and mild perifollicular inflammation were found to favor the diagnosis of CCCA. Dilated eccrine glands and heavy perifollicular inflammation were found to favor the diagnosis of LPP. Study 2 was a prospective cross-sectional data analysis study designed to identify and compare direct immunohistochemical findings in patients with LPP or CCCA. Vertical frozen sections of scalp biopsies from eleven patients (4 CCCA and 7 LPP) were stained with IgG, IgA, IgM, C3 and fibrinogen. No DIF finding that reliably distinguishes LPP from CCCA was found. The presence of a positive DIF was significantly correlated with the amount of inflammation. Study 3 investigated and compared T lymphocyte subsets, including T helper cells, cytotoxic T cells, Th 17 lymphocytes and regulatory T cells between LPP and CCCA cases. Subjects in this study were identical to study 2. There were no significantly distinctive T lymphocyte populations that differentiate between CCCA and LPP. There were higher numbers and percentages of CD8 positive cells in LPP compared to CCCA. The CD4:CD8 ratios were decreased in LPP and increased with duration of disease approaching proportions found in the normal hair follicle and CCCA. There were higher CD1a:CD3 ratios in LPP compared to CCCA. The CD1a:CD3 ratios in LPP decrease over time, approaching those found in CCCA. Results of this study confirm role of Langerhans cells as antigen presenting cells and role of cytotoxic lymphocytes in pathogenesis of LPP in early disease. Th17 lymphocytes and Tregs may have a role in both CCCA and LPP