We report two cases of pigmentary dilution: one patient with Griscelli syndrome (GS) and another with Chediak-Higashi syndrome (CHS). Those rare conditions with potentially fatal complications comprise hair color abnormalities. Microscopic examination of the hair shaft can be a major diagnostic tool.
The first patient was a 11-years-old boy referred for silvery discoloration of hair and eyebrows. At the age of five weeks, he developed bronchiolitis followed by haemophagocytic lymphohistiocytosis. The diagnosis of type 2 GS was made. He was treated by bone marrow transplantation from his compatible healthy twin brother. His one year younger sister was also affected and treated the same way. At the age of 11, we noted hair and eyebrows with a silvery aspect, one café-au-lait macule, discrete leucomelanoderma of the limbs and multiple abdominal lentigos. The psychomotor development was normal but the pigmentary abnormalities persisted after transplantation.
Microscopic examination of the hair revealed numerous unevenly distributed large clumps of pigment in the hair shaft.
The second patient was a 10-month-old girl who developed multiple respiratory infections during the first weeks of life. She was hospitalized for intestinal and respiratory symptoms associated with fever. The diagnosis of CHS was made by the examination of a peripheral blood smear showing typical neutrophil inclusions. The physical examination showed pigmentary dilution in comparison with her parents’ hair, with iridian hypochromia and silvery discoloration of her hair and eyebrows. No nystagmus was found.
Microscopic examination of the hair revealed large clumps of melanin scattered along the hair shaft.
The skin examination is not specific in GS or CHS : cutaneous pigmentary dilution is sometimes discrete and mostly visible when compared with familial phototype. Both conditions include silver discoloration of hair and eyebrows, which can be easily observed under the microscope. Moreover, this very simple exam enables the differential diagnosis between CHS and GS.
In GS, melanin deposits are larger than those seen in normal hair. With polarized light, the hair shaft is shiny with a monotonous whitish appearance. In CHS, small clumps of melanin are regularly disposed in the center of the hair shaft. They are a little bigger than the ones seen in normal hair. When examined with polarized light, the hair shaft is brilliant with different colors, which is very different from GS monochrome hair.
Microscopic examination of the hair shaft can be easily and quickly performed. It is a non invasive and non expensive diagnostic tool, which is very useful to make the differential diagnosis between GS and CHS.
Bourlond F, Cribier B, Lipsker D
Dermatology Department, Hôpitaux Universitaires de Strasbourg, Strasbourg, France