SIR, Molluscum contagiosum (MC) is a poxvirus skin infection that often complicates the course of patients with acquired or iatrogenic immunosuppression. 1±3 Both the clinical and histological features of disease in these cases may be atypical. We report the unique clinical and histological features of a case of fulminant MC infection with concomitant leukaemia cutis in a patient with relapse of chronic myeloid leukaemia (CML) after allogeneic bone marrow transplantation (BMT). A 49-year-old Chinese woman underwent BMT (conditioning: busulphan, cyclophosphamide, total body irradiation) from an HLA identical sister for Ph positive CML in accelerated phase. She engrafted uneventfully with no chronic graft-vs.-host disease (GVHD). Serial bone marrow reassessments, up to 18 months post-BMT, were negative for residual disease by polymerase chain reaction and cytogenetics. At 36 months, she was found to have haematological relapse of CML, with cytogenetic subclonal evolution. She was treated with hydroxyurea and donor lymphocyte infusions (DLI)(6 1 x 108 kg21 cells infused in three doses) to enhance the graft-vs.-leukaemia (GVL) effect. There was good control of the peripheral cell counts and no evidence of GVHD. A repeat marrow biopsy at 40 months showed suppression of the abnormal clone to 3% of analysed metaphases. Unfortunately, at 46 months the disease progressed again with increased neutrophil counts (52 x 109 L21), and leukaemia cutis documented by skin biopsy (Figs 1a, 1b). This was treated with combination chemotherapy (cytosine arabinoside 150 mg x 5, thioguanine 160 mg x 5) resulting in normalization of cell count and resolution of all skin lesions. A second course of DLI (4 2 x 108 kg21 cells) was administered at 49 months post-BMT. Three weeks after DLI, however, the patient presented with a dense eruption of erythematous papular lesions over the entire face, upper limbs and upper trunk. Photography of the lesions was refused. A biopsy of one lesion showed lobules of abnormal epidermal cells with cytoplasm packed with eosinophilic viral inclusion bodies (Fig. 2a). Electron microscopy showed numerous intracytoplasmic poxvirus particles (240 x 95 nm in size) within the abnormal epidermal cells, consistent with MC (Fig. 2b). In addition, an infiltrate of promyelocytes and immature myeloid blast cells was seen, consistent with recurrent leukaemia cutis. She died 1 week later of an intracranial haemorrhage, probably related to intracerebral disease. The use of DLI is the treatment of choice for relapse of CML after BMT. 4 The main side-effects are profound marrow and immune suppression, with or without acute and chronic GVHD. Reactivation of dormant DNA viruses like cytomegalovirus, varicella zoster and hepatitis B viruses are potential complications of immunosuppression caused by DLI. This is the first report of severe MC complicating DLI. In immunosuppressed hosts, due to the fulminant replication of the poxvirus, the clinical and pathological features of MC can be highly variable, 1, 2 and aggressive treatment is often needed. 1 Viral particles have even been found in the histologically normal skin epidermis adjacent to MC lesions in patients infected with HIV. 3 There have been two previous reports of skin changes in MC mimicking haematological malignancy involving the skin. 5, 6 In our case, the clinical setting and pathological features are highly supportive of a genuine double pathology. It is recognized that post-BMT patients have an increased incidence of leukaemic involvement of extramedullary sites, including the skin. 7 The incidence may be even higher in patients salvaged with DLI, due to a …