An open-access paper describes PIILIF, a hidden follicle-centered inflammatory pattern that may interfere with standard pattern hair loss treatments, even in normal-appearing scalp.
Researchers at Dr U Hair and Skin Clinic in the Los Angeles area report that an inflammatory, early fibrotic pattern within androgenetic alopecia (AGA), male pattern baldness and female pattern hair loss, may help explain why some people stop responding to standard “AGA-only” hair loss treatments and why results can be unpredictable in advanced or complex cases.
The findings appear in Clinical, Cosmetic and Investigational Dermatology.
The paper describes PIILIF, a follicle-centered pattern of inflammation and early fibrosis around the upper part of the hair follicle. PIILIF can coexist with AGA and may be present even when the scalp appears normal.
“Many hair loss sufferers do all the right things, including minoxidil, finasteride, and even hair transplantation, yet still experience disappointing outcomes,” says Sanusi Umar, MD, board-certified dermatologist and lead author, in a release. “In a meaningful subset of AGA patients, an inflammatory and early fibrotic driver may be operating in parallel. When that biology is missed, results predictably fall short.”
Study Design and Key Findings
Researchers retrospectively analyzed 129 AGA patients from a referral-center cohort. Using high-magnification imaging to guide biopsies from thinning and normal-appearing scalp, they linked microscopic findings to clinical features and outcomes.
Highlights include:
- PIILIF was identified in normal-appearing scalp in 81% of patients, especially among patients aged 44 and older, with advanced hair loss or baldness, or prior poor response.
- Despite frequent labeling as ” seb derm” or “dandruff,” true seborrheic dermatitis was confirmed on biopsy in only 0.8% of the cohort; PIILIF was present in 81%.
- Among evaluable AGA-PIILIF patients treated with a plan addressing hormonal drivers and follicle-centered immunologic inflammation, 67% improved and 2% had suboptimal outcomes.
- Findings support an AGA–PIILIF spectrum and suggest a dual-pathway strategy, hormonal plus immune-based inflammatory/fibrotic control when indicated, in treatment-resistant hair loss and pattern baldness.
The paper also proposes that fibrosing alopecia of patterned distribution aligns with a later AGA-PIILIF stage and recommends staging AGA-PIILIF by perifollicular fibrosis to support earlier recognition and intervention.
What This Means for People Not Responding
Most plans focus on dihydrotestosterone control and follicle cycling support with finasteride and minoxidil. But when immune-type inflammation and early fibrosis are active around follicles, “more of the same” may not be enough. This does not mean everyone needs a biopsy. For non-responders, the study supports better biology control, better targeting, and better timing, with earlier diagnostic confirmation in unclear or high-stakes cases.
When PIILIF is present, the goal is not only to stimulate hair growth, but to stabilize the scalp environment. The findings support long-term, steroid-sparing anti-inflammatory strategies, similar in principle to approaches used in scarring alopecias, when clinically appropriate.
Why It Matters for Hair Transplant Planning
In advanced, donor-limited, repair or post-procedure underperformance cases, scalp biology can affect predictability and durability. When inflammatory-pattern biology is suspected, the findings support scalp optimization and biopsy-informed planning rather than automatically escalating to additional grafting.
The authors encourage clinicians to adopt structured screening and management pathways to recognize inflammatory-pattern AGA earlier and integrate dual-pathway, long-term management when indicated. Umar presents one example, the Inflammatory AGA Screen (PIILIF Track) , as a model others can adopt and refine.
Photo caption: A patient with Norwood 7 pattern baldness and a prior strip-surgery treatment scar before treatment (left) and eight months after hair transplantation performed alongside PIILIF-directed management (right).
Photo credit: Dr U Hair and Skin Clinic
