Glans metastatic extra-nodal natural killer/T-cell lymphoma, nasal-type with HDAC inhibitor as maintenance therapy: a rare case report with literature review.

Extra-nodal natural killer/T-cell lymphoma (ENKTL) is an aggressive lymphoid malignancy and advanced ENKTL is characterized by a dismal survival outcome. Distant metastasis is frequently common in advanced ENKTLs, while the glans is rarely involved. Here we report a 67-year-old Chinese male with glans metastasis ENKTL, nasal type secondary from the nasal cavity, treated with modified SMILE regimen plus glans radiotherapy and achieved a complete remission (CR). Since the poor prognosis of metastatic ENKTL and unfitness for hematological stem cell transplant (HSCT), we administered histone deacetylase (HDAC) inhibitor Chidamide as maintenance therapy, which was resulted in a progression-free survival (PFS) of 12 months. To investigate the gene alternations, the whole exon sequencing and the 446-gene panel sequencing were performed and we found the BCOR, KRAS, CDKN1B, XPO1, DOT1L genes mutations. Best to our knowledge, this is a glans metastasis ENKTL with the longest PFS and the most successful treatment.