Postoperative pressure-induced alopecia: report of a case and discussion of the role of apoptosis in non-scarring alopecia

We report a case of postoperative pressure induced alopecia in a 21-year-ol d black female after multiple intraoperative procedures. The histopathology is distinctive and demonstrated features in common with trichotillomania a nd alopecia areata, including the presence of pigment casts, catagen follic les, melanophages and apoptotic bodies. External hair manipulation is consi dered the primary event in the etiology of pigment casts, however, our pres ent case demonstrated numerous pigment casts despite a complete lack of evi dence of external hair manipulation. Mie performed pattern analysis and in situ end-labeling in 19 cases of non-scarring alopecia. Pigment casts were seen in postoperative alopecia (1 case), alopecia areata (1 case) and trich otillomania (5 cases). These forms of alopecia have in common the sudden te rmination of the anagen phase of the hair cycle. When the anagen portion of the hair cycle is prematurely disrupted hairs enter into catagen. Pigment casts may represent a non-specific reaction pattern of follicles that are s uddenly transformed from anagen to catagen. We therefore propose that hair manipulation is not uniquely responsible for the formation of pigment casts . The primary pathophysiology resulting in the formation of pigment casts m ore correctly reflects the sudden termination of the anagen phase of the ha ir cycle.