Contrast enhanced phototrichogram pinpoints scalp hair changes in androgen sensitive areas of male androgenetic alopecia.

BACKGROUND/AIM: In male androgenetic alopecia (AGA), global changes of scalp hair observed on many years are the cumulative result of discrete changes. Such changes reflect structural and/or functional modifications occurring at the level of individual hair follicles. The patterning of scalp hair loss is the phenotypic expression of clusters of hormone sensitive follicles located in specific scalp areas. The aim of this study was to evaluate, in 21 untreated male subjects with AGA, the relation between various hair measurements using a new validated photographic method with clinical staging (modified Norwood-Hamilton scale) as compared with five controls.

METHODS: As recently demonstrated by comparison with transverse sectioning of scalp biopsies, dynamic changes occurring at the level of individual hair follicles can be accurately explored with the contrast enhanced phototrichogram technique (CE-PTG). This is a further improvement of the PTG (combined analysis of two photographs taken at 48 h interval) using contrast enhancement together with the scalp immersion proxigraphy method. Visible hair counts per unit area were first evaluated on photographs without and with CE. Then other scalp hair variables (anagen hair counts and proportion of thin hair (
RESULTS: We confirm that the CE improves hair detection. Controls showed higher densities in the top of the head sites as compared with the occipital ones. In the presumably less hormone responsive scalp occipital sites, AGA subjects did not differ from controls. The top of the head sites, i.e. highly androgen sensitive areas of AGA subjects showed a reduction of total and anagen hair counts as compared to controls. These changes were observed even in mildly affected subjects. The clinical severity of AGA seems to be related to the reduction of anagen counts and the associated relative increase of thin hair. Because the thinnest hair usually lacks pigmentation, they escape detection by PTG in the absence of contrast enhancement. The CE-PTG also detects higher proportions of thin hair at early stages of AGA as compared with light microscopy. This probably reflects lack of control during the sampling process, i.e. the clipping- collection-display sequence required for light microscopy observations.

CONCLUSION: These results indicate that CE-PTG is a powerful tool for analysis of hair growth and loss and may cast some doubt on results obtained with other methods. The potential use of the CE-PTG method for calibration of innovative tools is also alluded to. Indeed encouraging results have been obtained with the scalp coverage scoring (SCS) method. These SCS scores were correlated with shortening of anagen phase and hair miniaturization, the two processes apparently involved in the clinical development of male AGA.