STAT6 Mutational Status in Primary Mediastinal B-Cell Lymphoma with STAT6 Nuclear or Cytoplasmic Expression by Immunohistochemistry (USCAP 2023)
Clinicopathologic Characteristics of 7 Patients with STAT6 Nuclear or Cytoplasmic Expression by Immunohistochemistry Abbreviations* F: Female; M: Male; NA: Not applicable; IHC: Immunohistochemistry; RCHOP: Rituximab, cyclophosphamide, doxorubicin hydrochloride (hydroxydaunorubicin), vincristine sulfate (Oncovin), and prednisone; R-EPOCH: Rituximab, etoposide, vincristine, doxorubicin, cyclophosphamide; CR: Complete remission; PMBL: Primary mediastinal B-cell lymphoma; ABVD: Doxorubicin hydrochloride (Adriamycin), bleomycin sulfate, vinblastine sulfate, and dacarbazine Figure 1: Click to view full size STAT6 IHC+ was detected in ~40% of patients in our cohort. STAT6 IHC+ was detected in ~40% of patients in our cohort. About half of STAT6 IHC+ cases with nuclear or cytoplasmic staining patterns harbored STAT6 mutations, all in exon 12 (predominantly D419 mutations). No strong correlation between positive STAT6 mutations and STAT6 IHC+ (nuclear or cytoplasmic) was appreciated in this cohort, arguing against the utility of STAT6 by IHC as a surrogate marker for STAT6 mutational status.