非瘢痕性脱毛症に対するポリ乳酸（PDLLA）頭皮微量注入法とオプションのライトマイクロニードリングプライミング：前向きパイロット症例シリーズ

PDLLA demonstrates angiogenic and regenerative properties that may support hair regrowth by enhancing perifollicular perfusion. Objective: To evaluate clinical improvement after PDLLA scalp microinjection in 20 patients using standardized photography and Global Aesthetic Improvement Scale (GAIS) rated by two independent physicians.

Twenty adults with non scarring alopecia received PDLLA scalp microinjections at baseline and week 4 (optional booster at week 8). Optional light microneedling priming (0.5-0.8 mm) was performed immediately before PDLLA injection in 14/20 patients to facilitate distribution. Primary endpoint was physician rated GAIS at week 12; secondary endpoints included patient GAIS and safety. Images were acquired with fixed camera to scalp distance and lighting.

Physician GAIS improved in 90% of patients at week 12 (mean ± SD 3.3 ± 0.6) and was maintained at week 24 (3.1 ± 0.7). Patient reported GAIS was 3.2 ± 0.7 at week 12. No serious adverse events occurred.

In this pilot uncontrolled case series, PDLLA scalp microinjections were associated with physician‑rated GAIS improvement over 12-24 weeks with favorable short‑term tolerability. Given the subjective endpoint, the absence of a comparator arm, and optional microneedling priming in a subset of patients, the findings are preliminary and require confirmation in controlled studies with objective trichologic measurements and longer follow‑up.