Pili torti

Did You Know?

• Uneven growth of outer root sheath cells causes hair twisting in hereditary forms.
• In acquired forms, perifollicular inflammation followed by fibrosis deforms the hair follicle and generates rotational forces.
• Pili torti can be associated with conditions such as Menkes disease, Björnstad syndrome, and Netherton syndrome.

Signs and symptoms

Hair in pili torti is dry, coarse, brittle, and fragile, potentially leading to patchy alopecia. The scalp, especially the occipital and temporal regions, is most often affected, though eyelashes, pubic hair, axilla, and eyebrows may also be involved. Typically only a portion of the hair is impacted, and isolated pili torti can occasionally be found in an otherwise normal scalp. The condition may be linked to various local and systemic issues.

Causes

Pili torti may be acquired or inherited. Inherited forms include classic early onset (Ronchese type), late onset (Beare type), and pili torti associated with hereditary disorders. Classic early onset, appearing between the third month and third year of life, is autosomal dominant or recessive and more frequently affects blond girls, often improving after puberty. Late onset, manifesting after puberty, is autosomal dominant and more common in people with dark hair, typically presenting solitary twists. Acquired pili torti can result from medications such as epidermal growth factor receptor inhibitors, oral retinoids, sodium valproate, and carbamide perhydrate, or from dermatological conditions including cicatricial alopecias like lichen planopilaris, frontal fibrosing alopecia, and discoid lupus erythematosus.

Diagnosis

Diagnosis is made through trichoscopic and microscopic examination. Low-magnification trichoscopy reveals hair shafts bent at random intervals and varied angles, while high magnification shows regular twists along the long axis. Under the microscope, the shaft displays irregularly spaced clusters of three or four twists. The condition may be inherited or acquired, with acquired cases linked to medication side effects or systemic and dermatological disorders.

Treatment

No specific treatment exists for pili torti. Management focuses on preventing hair damage by avoiding dyeing, braiding, heat treatments, and over-grooming, and using gentle shampoos or sleeping on a satin pillowcase. Congenital cases may resolve after puberty, and drug-induced cases often improve upon stopping the offending agent. Treating the underlying condition is key for acquired forms. Topical minoxidil may improve hair density but does not address the underlying hair shaft abnormality.