Monilethrix Clinical Presentation

Updated: May 22, 2020
  • Author: Robert A Schwartz, MD, MPH; Chief Editor: Dirk M Elston, MD  more...
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Presentation

History

Monilethrix is a lifelong disease. Internodal fragility leads to breakage of hair and varying degrees of alopecia. Symptoms spontaneously regress during puberty and pregnancy, but the condition never disappears completely. Affected persons are generally healthy. They may report sparse and brittle hair since early childhood. [18]

Keratosis pilaris is almost invariably associated with monilethrix. Sites of predilection are the scalp, nape of the neck, and extensor surfaces of the upper arm and thigh. No evidence suggests that keratosis pilaris can lead to the formation of beaded hair. Koilonychia is commonly associated with monilethrix. A wide variety of concomitant ectodermal defects are reported in the literature. Examples include dental abnormalities, juvenile cataracts, and some neurologic defects that appear as a cognitive deficiency or epilepsy.

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Physical Examination

Lanugo hair usually appears normal at birth. Several months later, it is replaced by moniliform hair, which is dry, brittle, fragile, and lusterless. The hair breaks spontaneously to 0.5-2.5 cm. Broken short hair looks as if it has been burnt.

Monilethrix occurs mainly on the scalp, predominantly on the occiput and nape and occasionally on other scalp areas. Scalp involvement can be widespread or circumscribed. The eyelashes, eyebrows, pubic, axillary, and limb hair are occasionally involved.

Monilethrix is associated with follicular keratosis (horny follicular papules). Patients with monilethrix and a prolonged clinical course of several years' duration may have cutaneous atrophy (aplasia pilorum moniliformes [Latin]).

The absence of macroscopic beading should prompt repeated hair microscopy and not an automatic rejection of this diagnosis. [19] Dermatoscopy can be helping in making the diagnosis, especially with adequate hair sampling. It shows zones of dystrophic constriction of the hair shaft, separated at regular intervals by elliptical nodes of normal thickness, producing a "necklace" appearance. [18, 20]

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