Akute Pseudoalopezie unter dem Bild der rasierten Kopfhaut : Differentialdiagnose zur Alopezie

A 29 year-old man presented with acute hair breakage (pseudoeffluvium) on the frontal area of his scalp, caused by the application of a keratolytic chemical substance. The hair on the area involved was reduced to a stubble of about 1 mm in length and looked as though it had been shaven. We suggest the term pseudoalopecia for this phenomenon, to distinguish it from alopecia. Pseudoalopecia follows on from acute or chronic breakage of hair due to congenital or acquired hair shaft abnormalities. Clinically, the pseudoalopecias are characterised by unintended short hair. The hair length varies between that of a crew cut and a shaven head. The thickness of growth, trichogram of the roots and the histology remain unchanged. Under the light microscope one sees characteristic changes in the hair shafts with typical breakage sites. These changes can also be observed at the distal ends of the broken hair shafts still attached to the scalp. Therefore a distal trichogram (trichogram of the hair tips) is necessary for the diagnosis of pseudoalopecia. Since the cycle of hair growth is uninterrupted, the hair continues to grow normally. It is important to distinguish between alopecia and pseudoalopecia as there are fundamental differences in aetiology, pathogenesis, clinical picture, trichology, histology, prognosis and therapy.