The original 2021 system defined only Stages 0–IV. However, a small series of survivors (n=19) developed a chronic fatigue syndrome with persistent arthralgia and elevated serum IL-6 for >6 months. This has been proposed as . Diagnostic criteria require: documented acute SKTV infection, no alternative rheumatologic diagnosis, and a Fatigue Severity Score > 4. No specific treatment exists, but low-dose naltrexone is under trial.
: The surrounding tissue edema begins to subside, sharpening the margins of the ulcer. While the base is still covered completely by a necrotic slough layer, a subtle ring of localized hyperemic (reddened) tissue may emerge around the perimeter. 2. The Healing Stage (H) sakitamiwa classification
As treatment progresses, the ulcer enters the healing phase, characterized by the gradual reduction of the slough and the appearance of regenerative tissue. The original 2021 system defined only Stages 0–IV
The next iteration—Sakitamiwa 4.0 (expected 2026)—aims to incorporate liquid biopsy biomarkers (circulating tumor DNA, exosomal microRNAs) and artificial intelligence-driven whole-slide image analysis. Preliminary data suggest that AI-enhanced Sakitamiwa grading achieves 94% concordance with expert consensus, compared to 78% for human-only grading. While the base is still covered completely by
At its core, the system divides the ulcer healing process into three major sequential phases, which are then each subdivided into two distinct stages. This results in a total of six stages, which trace the ulcer from its most severe, active state (A) through the healing phase (H) and finally to the complete formation of scar tissue (S).