How dermal fat biology connects to acne scars.
Two acne scar categories sit on opposite sides of the same dermal-fat biology. Atrophic acne scars (icepick, boxcar, rolling) are defined by volume loss in the dermis: tissue that does not return to its pre-inflammation level after the acne lesion resolves. Hypertrophic and keloid acne scars are the opposite: excess fibrotic tissue above the skin surface.
What the published research suggests:
• The myofibroblast-to-adipocyte conversion is what determines whether skin heals to normal architecture or to scar tissue. Plikus et al. 2017 in Science showed that during wound repair, hair follicle signaling instructs myofibroblasts to convert into adipocytes, reconstituting the dermal fat layer and reducing fibrotic deposition (PMID 28059714). When that conversion happens efficiently, repair tends toward normal architecture. When it does not, repair tends toward scar tissue.
• Dermal adipocytes and dermal fibroblasts share the same mesenchymal progenitor lineage (Driskell et al. 2014 in Experimental Dermatology, PMID 24841073). The cells that make collagen-rich scar tissue and the cells that make dermal fat are lineage-adjacent. Which fate the progenitors take depends on the local signaling environment.
• TNF-α, an inflammatory cytokine elevated in active acne, upregulates matrix metalloproteinase expression in dermal fibroblasts and degrades the collagen matrix (Quan et al. 2009, PMID 19675548). Larger neighboring fat cells amplify those signals (Skurk et al. 2007, PMID 17164304).
Translation: an atrophic acne scar is the result of localized dermal inflammation degrading the surrounding architecture faster than it gets repaired, with the outcome depending in part on whether dermal fat regenerates locally.
Most acne scar conversations focus on the fibroblast and the collagen. The dermal fat compartment is part of the same conversation, viewed from a different angle. The published literature increasingly suggests both compartments matter for the outcome.
Please tell us if you find posts like this useful, and what acne-scar science topics you'd want covered next. And happy to go deeper on any of the above points in the comments.