Abstract: Primary cutaneous extranodal NK/T-cell lymphoma (PC-ENKTL) exhibits a variety of clinical manifestations, rapid disease progression, poor prognosis, and low cure rates. We report three cases of primary cutaneous extranodal NK/T-cell lymphoma, including one male patient and two female patients, with skin lesions located on the left outer ankle, left upper extremity, and right upper eyelid respectively. Skin lesions were characterized by erythema, blisters, nodules, erosions, ulcers and other lesions. Hematoxylin-eosin staining revealed extensive infiltration of tumor cells throughout the dermis in all cases. In situ hybridization revealed positive staining for EB virus encoded RNA (EBER) in all cases. Immunohistochemical examination showed positive for CD3, CD30, and Ki-67 (50%) in all cases, and positive for CD56 in cases 2 and 3. Case 1 showed improvement after chemotherapy combined with radiotherapy, but developed intracranial hemorrhage as a complication during treatment. Case 2 died from secondary lung infection after chemotherapy. Case 3 was lost to follow-up after having poor response to chemotherapy.

Key words: primary cutaneous extranodal NK/T-cell lymphoma, extranodal NK/T-cell lymphoma, cutaneou lymphoma