L'ESAME DEI CAPELLI: UNA CHIAVE PER LA DIAGNOSI Ramon ...

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Optical microscopy is essential in current practice. Specific abnormalities are easily detected: periodic narrowing of hair(monilethrix), ringed hair(pili annulati), trichoschisis and “tiger tail” hair(trichothiodystrophy) (5), atypical pili torti(Menkes’ syndrome) (6), TI(Netherton syndrome) (7), TN versus bubble hair, “ruffling”(loose anagen hair) (8). Scanning electron microscopy usually does not give further information but allows to differentiate monilethrix from pseudomonilethrix (irregular intermittent flattening of hair), and confirms the diagnosis of woolly/curly hair conditions or pili canaliculi. SEM is also useful for the study of hair weathering and cosmetic damage. X-ray microanalysis permits to detect sulfur aminoacids deficiencies (trichothiodystrophy) and the increase of a single element (cooper) green hair (9). Specific treatment for those hair diseases that do have one, and basic general approach to improve the cosmetic appearance of hair, will be also given for those hair disturbances that do not have a specific treatment (10). From our point of view, the most important aspects of hair dysplasia are the microscopical signs. We need to “read” the hair shaft alterations in order to be able to detect and to classify these disorders. On that purpose, we have divided the main microscopical signs into: Nodes, knots, flattening, twisting, curling and ringing. If we learn the “hair-language” as we did with the “skin-language” in our training in dermatology with papules, pustules, blisters... we shall be able to properly identify the trichological “elementary lesions” . It will be extremely easy to make a diagnosis in most hair dysplasias after the simple determination of the predominant microscopical sign. In we observe knots under the microscope, the diagnosis is extremely easy, the only possibility is trichonodosis, associated or not with trichoptilosis (split ends) and commonly associated also with compulsive hair manipulation(11). Nodes are very common on microscopical observation and may signify different diseases, depending of the type and distribution of the nodes. Flat irregular nodes are very suggestive of artefactual pseudomonilethrix (1). Regular nodes are typical of trichorrhesis nodosa, irregular nodes with fragility may indicate bubble hair. In monilethrix (2) the hair shaft may show at the first view regular round nodes. After accurate observation it is possible to see that in fact there are regular constrictions. This allows to differentiate monilethrix from other nodular shaft diseases. True monilethrix is clinically associated with keratosis pilaris and it has been etiologically well documented that there is a deficiency on the keratin 6. Nodes can also be observed in a hair displasya characterized by an increased hair fragility which is pseudomonilethrix (5). A flattened hair may be the microscopical sign of woolly hair, as also seen in the racial differences as the negroid hair, if it is extremely flattened and shows some crests and trichoschisis associated, is very suggestive of trichothiodystrophy. This is a group of diseases that represent in fact, a complex syndrome unified by the deficiency of sulfur on the hair shaft. Curly hair may be present in different variants of woolly hair, as the autosomal dominant woolly hair, autosomal recessive woolly hair, the woolly hair nevus, also present in the acquired progressive kinking of hair and in the diffuse partial woolly hair (12). 2
Ringing is only seen in pili annulatti. This shows a very characteristic bright and dark bands when viewed by reflected light. The bright bands are caused by light scattered from periodically occurring clusters of abnormal, air-filled cavities within the hair. This condition may be sporadic or familiar in the latter cases usually with an autosomal dominant pattern of inheritance. Etiology is unknown. Under the microscope, the dark areas correspond to those seen as bright regions by reflected light. Air-filled cavities do not permit light to pass through and therefore appear dark. The denomination pseudo pili-annulati or pili pseudo-annulatti (13)has also been used to describe normal hair with a strikingly banded appearance by reflected light. The banding resulting to superficial optical effects stemming from the peculiar geometry of the hair which might be elliptical in cross section and partially twisted in an oscillating manner along the fiber axis. Twisting is present in pili torti and in its variants. It might be clinically similar to pili annulatti, because in both diseases, hair may shine under light. It is a rare hair-shaft defect that when observed under the microscope, hair shows flattening and a regular twisting along its longitudinal axis. The twists are narrow, occur in groups of three to ten twists and give the hair a strikingly spangle appearance in reflected light. The hair is always brittle, fragile, and consequently broken and short. Pili torti is often misdiagnosed and can be also confused with monilethrix because an oval fiber, when twisted, resembles one with variations in diameter when seen in a light microscope. Different variants of pili torti have been described: Congenital pili torti or classic pili torti (Ronchese) , late onset pili torti (Beare), corkscrew hair, pili torti with cooper deficiency (Menkes) also called kinky hair, and the acquired pili torti in cicatricial alopecia. In conclusion, hair dysplasia in children can be easily oriented by the clinical observation, and by learning the language of the hair shaft when viewed under the microscope. Many diseases can be easily diagnosed by this extremely simple examination method. 3
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L'ESAME DEI CAPELLI: UNA CHIAVE PER LA DIAGNOSI Ramon ...

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