BTG3 and dermatitis herpetiformis, familial: As the literature of such documented reports is limited, this case suggests further investigations.<h4>Abbreviations</h4>GI: gastrointestinal tract, DLBCL: diffuse large B cell lymphoma, DH: double hit lymphoma, SLE: systemic lupus erythematosus, ANA: antinuclear antibodies, anti-ssDNA: anti-single-stranded DNA, BCL: B-cell lymphoma protein, MUM-1/IRF4: multiple myeloma oncogene 1/interferon regulatory factor 4, HGBL: high grade B-cell lymphoma, anti-dsDNA: anti-double-stranded DNA.