The presence of mast cells in lichen planopilaris and discoid lupus erythematosus of the scalp; a quantitative study

Evidence of interleukin-17-secreting mast cells in scalp lesions of folliculitis decalvans points to new therapeutic targets in recalcitrant lesions

Folliculitis decalvans (FD) is a chronic neutrophilic scarring alopecia, the exact pathogenesis of which remains unknown. A recent report on the successful use of a novel anti-interleukin (IL)-17 biologic agent to treat FD and the presence of IL-17-secreting mast cells in other types of scarring alopecias point to a distinct pathogenic mechanism in this disease. Our aim was to study and correlate the expression of IL-17 and mast cells in lesional and nonlesional scalp areas of patients with FD, using immunohistochemical techniques. There was significantly greater expression of IL-17 and mast cells in lesional compared with nonlesional scalp areas (P < 0.05). We also found a significantly positive correlation between IL-17 and tryptase-immunolabelled mast cells in nonlesional scalp (r = 0.64), highlighting the role of IL-17-secreting mast cells in 'normal-appearing' sites of FD. These findings suggest that novel treatments targeting both IL-17 and mast cells may be potentially beneficial in controlling the chronic inflammatory status of FD, especially for patients with recalcitrant FD.

Quantification of mast cells in central centrifugal cicatricial alopecia

Background

Mast cells (MCs) have recently been implicated in lymphocytic scarring alopecias, which may share a common pathogenesis. MCs in central centrifugal cicatricial alopecia (CCCA) have not been studied.

Objective

We looked for the presence of MCs in CCCA using 2 different stains to see if their numbers correlated with the number of hair follicles, the degree of inflammation and perifollicular fibrosis, disease duration and severity, and patient symptoms.

Methods

We performed a retrospective review of biopsies of patients diagnosed with CCCA, tabulated MC counts and correlated them with histopathologic and clinical findings.

Results

MC counts were significantly greater using immunoperoxidase staining with CD117 than Giemsa stain, and more were present when the isthmus level was included with the infundibulum. MC counts with CD117 immunostain significantly correlated with the degree of inflammation. MC counts with both stains were significantly associated with the degree of fibrosis independently and after controlling for other factors.

Limitations

The study was limited by insufficient tissue remaining in a small number of the transversely cut blocks.

Conclusion

Our findings may have therapeutic implications for CCCA and other types of lymphocytic scarring alopecia.