Extranodal NK/T-cell lymphoma (ENKTL) is a rare lymphoma subtype associated with Epstein-Barr virus (EBV) infection, portending a poor prognosis despite systemic chemotherapy. We present the unusual case of an 85-year-old man receiving ibrutinib for mantle cell lymphoma, who developed a erythematous, subcutaneous nodule on the forehead, featuring a proliferation of pleomorphic CD8 + /CD56 − /EBV + cells. Given the negative staging and comorbidities, a watchful waiting strategy was performed, experiencing a benign course with self-resolution and complete remission over a 4-year follow-up. The literature on primary cutaneous ENKTL has been discussed, with particular attention to clinical and histological prognostic factors.
