Abnormal inner root sheath of the hair follicle in the loose anagen hair syndrome: an ultrastructural study.

BACKGROUND: Loose anagen hair syndrome (LAHS) is a disorder in which the hair pulls out easily and painlessly from the scalp. It first manifests in early childhood when the main concern of parents is that the sparse hair does not grow. The hair density and length improve with age, but the looseness persists into adulthood.

OBJECTIVE: Light and electron microscopic studies of hair follicles were performed to better define the microscopic changes seen in LAHS.

METHODS: Biopsy specimens were obtained from 4 patients, 3 children and 1 adult. The hair follicles were studied by light and electron microscopy.

RESULTS: The most conspicuous structural changes were found in the inner root sheath complex of the anagen follicle. With light microscopy, the keratinized Henle cell layer showed a tortuous and irregular swelling. Irregular keratinization of the cuticle cells of the inner root sheath and a swollen appearance of Huxley cells were also found. With electron microscopy, the major pathological changes consisted of intercellular edema in the prekeratinized Huxley cell zone and dyskeratosis of Henle cells and cuticle cells of the inner root sheath.

LIMITATIONS: The studies were done on a small number of patients.

CONCLUSIONS: Structural abnormalities of the inner root sheath appear to disturb its normal supportive and anchoring function and result in a loose attachment of the hair shaft to the anagen follicle.