Pili annulati. Optical and scanning electron microscopic studies.

Abstract

An 18‐year‐old white man came to our Department of Dermatology complaining that his hair had been “shagreened” in appearance for 7 years (Fig. 1). Upon physical examination, his hair appeared normally resistant and abundant and was more than one palm long. The patient stated that his hair had never been subjected to physical stress such as traction or curling or any cosmetic treatments other than weekly shampooing.There was no family history of hair disease. The patient's medical history included vitiligo, which had developed 5 years before. Complete physical examination showed the patient to be normal for his race, sex, and age. There were no clinical or laboratory abnormalities except for the vitiligo and “shagreened” appearance of the hair; in particular, serum zinc levels were normal and there were no serum or urine amino acid abnormalities. Chromosome analysis gave normal findings.Hair specimens were mounted in Canada Balsam and observed by light microscopy. The hair shaft showed alternate bright and dark bands every 0.5 mm; the dark bands were distributed throughout the cortex of the hair, both centrally and peripherally (Fig. 2). Naturally, this pattern is not found in normal hair and was not observed in the normal control specimens. When viewed by reflected light, the regions previously seen as bright appeared dark and vice versa. Other hair segments were processed for transmission electron microscopy. They were fixed by 2 hours' immersion in 2.5% glutaraldehyde in 0.1 M cacodylate buffer, pH 7.4, at room temperature, and after 12 hours they were postfixed in 1.33% osmium tetroxide cacodylate buffer 0.1 M, pH 7.4, for 2 hours. The specimens were dehydrated in a series of graded ethyl alcohols (30%, 50%, 70%, and 100%) and then embedded in Epon 812. Sections 2 μ. thick were cut by an ultramicrotome with a diamond knife and then stained with both uranyl acetate and lead hydroxide. After rinsing, the sections were examined with a Philips EM 300 for transmission electron microscopy. Cross sections showed many wide holes ranging from 2–11 μ in diameter throughout the cortex. The holes appeared located both intracellularly and intercellularly (Fig. 3). The “empty” intercellular areas were between both the macrofibrillar and the microfibrillar structures of the hair. The areas between the macrofibrils appeared sometimes filled by a homogeneous electron dense material. The cell membranes occasionally presented herniation or bulging. Normal control hair cortex processed in the same way showed closely patched macrofibrils with few holes, less than 3 μ in diameter (Fig. 4).Hair segments were then processed for scanning electron microscopy. They were fixed for 6 hours at room temperature in 2.5% glutaraldehyde in cacodylate buffer 0.1 M and finally dehydrated in a series of graded ethyl alcohols (30–100%). The hair segments were mounted on aluminium stubs and sputtercoated with gold palladium 10%. The specimens were finally examined in a Philips SEM 515. A similar study was performed on normal controls hairs. Pili annulati showed a wide dishomogeneity of the cuticular scales distributed along the hair shaft. Peripheral hair shafts were occasionally without scales (Fig. 5). Normal control hair showed a regular arrangement of the cuticular scales over the entire hair shaft (Fig. 6).