154 Guidelines and techniques for the accurate classification of chemotherapy-induced hair follicle dystrophy

Bori Handjiski, Sven Müller-Röver, Eva M. J. Peters, Gerd Lindner, Ralf Paus. Dept. of Dermatology, University Hospital Eppendorf, University of Hamburg, Germany

In order to recognise even subtle forms of hair follicle dystrophy after pharmacological manipulation, it is critically important to be able to identify and accurately classify the distinct stages of the follicular response to damage and the corresponding degree of hair follicle dystrophy. We, therefore, have developed a set of simple and pragmatic classification criteria for chemotherapy-induced hair follicle dystrophy, using the C57BL/6J mouse model of cyclophosphamide-induced alopecia (Am J Pathol 144:719-34, 1994). We suggest to divide murine hair follicle dystrophy into six distinct stages: healthy anagen VI (HA), light dystrophic anagen VI (LDA), moderately dystrophic anagen VI (MDA), severe dystrophic anagen VI (SDA), dystrophic catagen (DC), and dystrophic telogen (DT). The basic classification criteria include: the structure and pigmentation of the hair shaft (continuous shaft and normal pigmentation during HA and LDA; broken shaft and disrupted pigmentation during SDA, DC and DT), the location and volume of ectopic melanin granules, the location, volume and shape of the dermal papilla (large and oval during HA and LDA; swollen during SDA; round and compacted during DC and DT) as well as abnormal widening of the hair canal (DC, DT). In addition, the following immunohistochemical markers aid in dystrophy classification: the number of TUNEL+ keratinocytes in the bulb as a marker for the level of dystrophy-associated apoptosis (HA: no; LDA >3; MDA >5, DC >10), the immunoreactivity for neural cell-adhesion molecule (NCAM) and alkaline phosphatase activity as a marker for the level of damage to the DP, as well as a broadly increased immunoreactivity for ICE (caspase-1), Bax, Fas/Apo-1, p53, p55TNFR, p75NTR and a decrease of bcl-2 immunoreactivity. These staging parameters not only offer a useful tool in murine models of chemotherapyinduced alopecia, but also when screening drug-treated mice for even discrete forms of hair follicle dystrophy in a highly standardised, reproducible, easily applicable, and quantifiable manner.