Table 2.
S100A81 and PRAME immunohistochemistry staining results in nevi and melanoma cases.
| Tumor type, n (%) | Common nevi (n=56) | Dysplastic nevi (n=54) | Melanoma in situ (n=58) | Melanoma (n=41) |
|---|---|---|---|---|
| S100A8 staining score: percentage of tumor-associated epidermis stained2 | ||||
| 1: 0–4% | 47 (83.9) | 42 (77.8) | 20 (34.5) | 3 (7.3) |
| 2: 5–25% | 8 (14.3) | 9 (16.7) | 11 (19.0) | 7 (17.1) |
| 3: 26–50% | 0 (0.0) | 2 (3.7) | 6 (10.3) | 10 (24.4) |
| 4: 51%–75% | 0 (0.0) | 1 (19) | 14 (24.1) | 8 (19.5) |
| 5: >75% | 1 (1.8) | 0 (0.0) | 7 (12.1) | 13 (31.7) |
| PRAME staining score: percentage of tumor stained2 | ||||
| Absent; 0% | 49 (87.5) | 22 (40.7) | 5 (8.6) | 1 (2.4) |
| Present, focal; <50% | 6 (10.7) | 19 (35.2) | 8 (13.8) | 6 (14.6) |
| Present, diffuse; >50% | 1 (1.8) | 13 (24.1) | 45 (77.6) | 34 (82.9) |
| S100A8 staining pattern for cases with staining scores ≥2 | ||||
| Predominately nuclear | 9 (16.1) | 11 (20.4) | 23 (39.7) | 20 (48.8) |
| Nuclear + cytoplasmic | 0 (0.0) | 1 (1.9) | 15 (25.9) | 18 (43.9) |
| Not applicable | 47 (83.9) | 42 (77.8) | 20 (34.5) | 3 (7.3) |
1
S100A8 IHC staining reported in: Kiuru M, Kriner MA, Wong S, et al. High-Plex Spatial RNA Profiling Reveals Cell Type–Specific Biomarker Expression during Melanoma Development. J Invest Dermatol. May 2022;142(5):1401–1412.e20. doi:10.1016/j.jid.2021.06.041
2
A positive staining score was defined as greater than 50% staining.