Primary cicatricial or scarring alopecias (CA) are a group of inflammatory hair disorders of unknown pathogenesis characterized by the permanent destruction of the hair follicle. The current treatment options are ineffective in controlling disease progression largely because the molecular basis for CA is not understood. Microarray analysis of the lymphocytic CA, Lichen planopilaris (LPP), compared to normal scalp biopsies identified decreased expression of genes required for lipid metabolism and peroxisome biogenesis. Immunohistochemical analysis showed progressive loss of peroxisomes, proinflammatory lipid accumulation, and infiltration of inflammatory cells followed by destruction of the pilosebaceous unit. The expression of peroxisome proliferator-activated receptor (PPAR) γ, a transcription factor that regulates these processes, is significantly decreased in LPP. Specific agonists of PPARγ are effective in inducing peroxisomal and lipid metabolic gene expression in human keratinocytes. Finally, targeted deletion of PPARγ in follicular stem cells in mice causes a skin and hair phenotype that emulates scarring alopecia. These studies suggest that PPARγ is crucial for healthy pilosebaceous units and it is the loss of this function that triggers the pathogenesis of LPP. We propose that PPARγ-targeted therapy may represent a new strategy in the treatment of these disorders.
Background: Traction alopecia is hair loss due to prolonged or repetitive tension on the hair. Diagnostic challenges may be encountered if the clinical suspicion for traction is not high, or if the history of traction is remote or not obtained. Since pathologic features can vary dramatically with the stage of the disorder clinico-pathologic correlation is essential. We have made the observation that the presence of retained hairs along the frontal and/or temporal rim, which we termed the "fringe sign", is a finding that can be see in both early and late traction alopecia, and thus may be a useful clinical marker of the condition. Objective: To determine the frequency of the fringe sign in a series of patients with a diagnosis of traction alopecia. Methods: This was a retrospective single-center review. Results: Over a 3.5 year period the diagnosis of traction alopecia was made in 41women. Twelve of the 41 patients were Hispanic (29%). The average age of our cohort was 34. Thirty-five (85%) of all women and 100% of women who had traction involving the marginal hair line had the fringe sign. The majority of African American women (54%) compared to 17% of the Hispanic women had some clinical sign of scalp inflammation(most frequently scalp scaling). Fourteen biopsies(58%) were available for review. Histopathologic findings included retained sebaceous glands (100%) and an increase in vellus-sized hairs (50%), a decrease in terminal hairs (100%), fibrotic fibrous tracts (100%), and sparse lyphocytic inflammation (57%). Trichomalacia was only noted in only one of the biopsies. Limitations: Retrospective analysis, uncontrolled study. Conclusions: Hispanic women as well as African American women are at high risk for traction alopecia. The fringe sign was a sensitive and specific clinical feature of traction alopecia when it involved the marginal hair line. Retained sebaceous glands, decreased terminal hairs, and fibrotic fibrous tracts were noted in all histopathologic specimens.
Use of these measures will facilitate collection of standardized outcome data on therapeutic agents used in alopecia areata both in clinical practice and in clinical trials.
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