All five signs follow the same 28-day biological cycle — which is, not coincidentally, the natural turnover rate of the skin.
Stage 1 — Friction. Your body's movement creates micro-fissures in the skin barrier. This happens in all five regions at the same time: thighs, bikini line, underarms, under the breasts, and even on your face.
Stage 2 — Bacterial colonization. The open barrier becomes a gateway for Staphylococcus aureus. The bacteria enters the follicle (bikini line, underarms) or settles into trapped moisture (under the breasts). Folliculitis appears. Intertrigo appears.
Stage 3 — Chronic inflammation. Every inflammatory episode triggers a cascade mediated by the proteins COX-2 and NF-κB. That inflammation activates local melanocytes.
Stage 4 — Post-inflammatory pigmentation. Activated melanocytes produce excess melanin exactly where inflammation occurred. The result is the dark spot that stays — on the thigh, on the bikini line, on the underarm.
On day 28, you shave again. And the cycle starts over, this time on top of a barrier that never recovered from the previous one.
That's the same cycle, in five regions. That's why the five signs travel together. That's why treating one never works. And that's why the dull skin of sign #5 is a consequence — not an autonomous condition. When the barrier in the other four regions is in a state of chronic inflammation, the skin across your entire body loses the ability to reflect light properly.