Acquired Hair Texture Alteration After Regrowth in Alopecia Areata: A Distinct Clinical and Ultrastructural Phenotype.

BACKGROUND

Post-regrowth hair texture alteration between straight and curly or kinked hair is rare and poorly understood in alopecia areata (AA).

OBJECTIVE

To characterize clinical and ultrastructural features of this phenomenon.

METHODS

A retrospective multicenter case-control study of AA patients and a systematic literature review were performed. Clinical, dermoscopic, and scanning electron microscopy (SEM) findings were analyzed.

RESULTS

Twenty-nine cases and 145 controls were enrolled. Univariable analysis showed hair texture alteration was more frequent in females and those with severe-to-very-severe diffuse AA or totalis/universalis. Most hair texture alterations occurred 4-12 weeks following Janus kinase (JAK) inhibitors and/or systemic steroid therapy, or following spontaneous hair regrowth. SEM revealed acquired pili torti, characterized by flattened hair shafts, segmental longitudinal grooves, and 180° axial twisting. The literature review identified five additional cases, expanding the therapeutic spectrum to topical/intralesional glucocorticoids and diphenylcyclopropenone (DPCP). In our series, 17.2% (5/29) of patients reverted to their original straight texture after 7 (7.0, 12.5) months, while others remained curly at a median follow-up of 12 (6.0, 18.0) months.

LIMITATIONS: Retrospective design.

CONCLUSION

Hair texture alteration after AA regrowth represents a distinct, underrecognized phenotype, likely reflecting intrinsic hair shaft abnormalities during follicular recovery rather than treatment effects.