Immunohistochemical Assessment of Ki‑67 Hotspots in Subcutaneous Panniculitis‑Like T‑Cell Lymphoma

Recommended Immunohistochemical Panel

• Include Ki‑67 immunostaining as a core component of a limited panel for evaluating suspected subcutaneous panniculitis‑like T‑cell lymphoma (SPTCL) to identify proliferative hotspots. 1

Dual‑Color Staining Techniques

• Apply dual‑color immunohistochemistry (e.g., Ki‑67/MART‑1 or Ki‑67/CD8) to specifically highlight proliferating cytotoxic T‑cells while excluding non‑melanocytic or non‑T‑cell proliferative elements, enhancing diagnostic precision. [2][1]

Quantification Protocol

• Perform manual counting of at least 2,000 cells within identified hotspot fields to obtain an accurate Ki‑67 proliferation index; note that the optimal standardized quantification method remains under investigation. [3][4]

Standardization and Quality Considerations

• Recognize that Ki‑67 quantification shows variable reproducibility across laboratories; when feasible, obtain central pathology review to mitigate inter‑institutional variability. [5][6]7
• Ensure optimal specimen handling—fixation in neutral‑buffered formalin for 4–48 hours and adequate subcutaneous tissue depth—to preserve Ki‑67 staining quality and reliability. [5][1]