Molecular analysis and histomorphological reevaluation reveal AITL diagnosis in cHL recurrence. Histomorphology and molecular data of the recurrence sample of case 5. (A) The normal lymph node architecture has been replaced by a polymorphous infiltrate consisting of small- and medium-sized lymphocytes with scattered cells having large nuclei and prominent nucleoli, some of which are consistent with HRS-like cells. High-endothelial venules are prominent. The large cells show strong expressions of CD30 and PAX5 and a weak expression of CD79a. Epstein-Barr encoding region (EBER) in situ hybridization shows scattered positive cells of different size. Anti-CD3 staining reveals numerous small- to medium-sized T cells. Many of these cells are positive for programmed cell death protein 1 (PD1) (data not shown) and a small proportion shows expression of CD10 and BCL6. Anti-CD23 staining demonstrates slight expansion of irregular dendritic meshworks. The original magnification (×10, ×20 and ×40) is indicated. (B) TR-NGS clonality analysis shows the presence of clonal TRBD- TRBJ and TRGV- TRGJ rearrangements. Targeted mutation analysis reveals mutations in AITL-associated genes TET2 and RHOA; VAF is indicated. (C) Summary of morphological reevaluation of the samples with a dominant TCR clone with integration of molecular findings. In total, 7 samples of 5 patients were indicative for TCL.