A case report described hair repigmentation and regrowth during baricitinib treatment in a patient with canities subita and concurrent alopecia areata.
The authors reported the case of a 60-year-old male patient with rheumatoid arthritis who was receiving etanercept and presented with sudden whitening of scalp hair. He had no personal or family history of alopecia areata or pigmentation disorders, denied use of bleaching agents, and reported no identifiable stressful triggers.
On examination, the patient had an absence of pigmented scalp hair, an alopecic patch in the occipital region, and loss of eyebrows, eyelashes, and body hair. Dermatoscopic findings were described as highly indicative of alopecia areata, although no biopsy or histopathologic confirmation was reported. Based on the clinical presentation, the authors diagnosed canities subita with concomitant alopecia areata.
Following consultation with rheumatology physicians, etanercept was withdrawn and baricitinib 4 mg/day was initiated. Signs of pigmented hair were observed 4 months following baricitinib initiation. By 8 months, the authors reported complete hair repopulation of the scalp, eyelashes, eyebrows, and body, along with resolution of the occipital alopecic patch. The accompanying images showed denser, grayer hair rather than a return to the patient’s apparent baseline pigmentation. No adverse events were reported, and the patient’s rheumatoid arthritis remained in clinical remission.
The authors noted that there is no established treatment for canities subita. They selected baricitinib because of the patient’s concurrent alopecia areata, the hypothesis that canities subita may represent a manifestation of alopecia areata, the potential for a Janus kinase inhibitor to address both rheumatoid arthritis and suspected alopecia areata, and prior evidence supporting baricitinib in alopecia areata. Baricitinib received U.S. Food and Drug Administration approval for alopecia areata in 2022 based on two phase 3 trials.
The case report supported, but did not prove, a proposed link between canities subita and alopecia areata. The authors noted that alopecia areata may preferentially affect pigmented hairs while sparing nonpigmented hairs, and that hypopigmented hair may predominate during early regrowth. They also cited experimental evidence suggesting melanocyte peptides may act as autoantigens in alopecia areata through CD8-positive T-cell–mediated immune responses against hair follicle melanocytes.
However, the authors emphasized that canities subita may have other mechanisms. In a retrospective review of 196 published case reports, alopecia was reported in 11.7% of patients diagnosed with canities subita. Other proposed explanations have included air inclusions in the hair cortex and overlap with pigmentation disorders such as vitiligo or piebaldism.
The findings were limited by the single-patient case report design, absence of a comparator group, lack of standardized alopecia severity or pigmentation outcomes, and clinical diagnosis without histopathologic confirmation. The concurrent withdrawal of etanercept was also an important confounder. Tumor necrosis factor inhibitors, including etanercept, have been associated with paradoxical alopecia areata, raising the possibility that etanercept contributed to the patient’s presentation and that its discontinuation may have contributed to improvement independent of baricitinib. Spontaneous remission of alopecia areata also could not be excluded.
The report should not be interpreted as establishing baricitinib as an effective treatment for canities subita. In addition, use of baricitinib for canities subita would be off-label, and any potential use would need to be weighed against Janus kinase inhibitor safety risks, including serious infection, malignancy, major adverse cardiovascular events, and thrombosis.
“In this patient, the co-occurrence of clinical signs of AA, the presence of diffuse hair loss, and a positive response to baricitinib treatment strengthens the hypothesis that canities subita may constitute a subtype of AA,” wrote lead author Lluís Corbella-Bagot, of Hospital Clínic Barcelona, and colleagues.
Disclosures: The authors reported no conflicts of interest and no external funding.
