86 © 2004 European Academy of Dermatology and Venereology CASE REPORT JEADV (2004) 18, 86 – 88 Blackwell Publishing Ltd. Blastic natural killer cell leukaemia with skin involvement: a case report E Kaya,† H Ozcan,‡ I Kuku,† M Dikilitas,§ A Sevinc,§ I Aydogdu†* Departments of †Haematology, ‡Dermatology and §Internal Medicine, Turgut Ozal Medical Center, Inonu University, Malatya, Turkey. *Corresponding author, Inonu University, School of Medicine, Department of Haematology, Turgut Ozal Medical Center, TR-44069 Malatya, Turkey, tel. +90 422 3410660/4201; fax +90 422 3410728; E-mail: iaydogdu@inonu.edu.tr ABSTRACT Natural killer cell leukaemia is generally accompanied by extramedullary involvement. CD4+ natural killer cell leukaemia frequently manifests with cutaneous involvement. The disease pursues a very aggressive course with no long-term survivors reported. We present a patient with CD4+ natural killer cell leukaemia with skin, bone marrow and peripheral blood involvement who is still on remission at the end of 2 years. Key words: CD4, CD56, immunophenotyping, leukaemia, natural killer cell, skin neoplasms Received: 14 March 2002, accepted 23 August 2002 Introduction Large granular lymphocytes (LGLs) are lymphocytes with pale blue cytoplasm and their cytoplasm:nucleus ratio is increased in favour of cytoplasm. Their significant morphological feature is the presence of large azurophilic granules in the cytoplasm. They form 5%-15% of the peripheral blood lymphocytes. LGLs are immunologically divided into two lineages as CD3- and CD3+. CD3- LGLs, also known as natural killer (NK) cells, play a role in host defence against microorganisms, in preventing tumour occurrence and metastasis, in the regulation of haemato- poesis and in T cell differentiation. 1 NK cells express CD2, CD16 and CD56 but not CD3, TCR-α / β and sIg. CD3- NK cell proliferation is observed in two different clinical forms: (1) chronic NK cell lymphocytosis and (2) NK LGL cell leukaemia. Although malignant lymphoid diseases developing from NK cells are rare, they have been described increasingly in the last decade with the frequent use of immunophenotyping in diag- nosis. 2 In this paper, we present a case of NK cell leukaemia with skin, bone marrow and peripheral blood involvement. Case report A 16-year-old boy was admitted to hospital with a rash and mass on the left forearm. There were haemorrhages in both of the scleras; palatum molle was oedematous and ecchymotic. There were bilateral lymphadenomegalies between 1 × 0.5 cm and 4 × 3 cm in diameter in the cervical region, 1 × 1 cm and 1 × 2 cm in the right axilla and 3 × 4 cm, 1 × 1 cm and 1 × 2 cm in the left axilla. There was a hard, painless mass in the right upper region of the torso under the clavicle and the mass lesion was fixed to the underlying tissue, having a black surface with ecchymosis around (fig. 1). It was 8 × 6 cm in size and there was a similar lesion in the left triceps region with a size of 10 × 6 cm (fig. 2). Dark brown-black nodular lesions between 0.5 and 1.5 cm in size were observed on the torso, back upper extrem- ities, face and scalp. Hepatomegaly was palpated 2 cm below fig. 1 NK cell tumour and echymotic lesions in the right upper region on the torso.