An young boy with an atypic rash]

We present a case of an 11-year-old boy originally from a Middle East country. He presented with blue nodules and flat blue lesions in skin/subcutis. The lesions involved greater parts of his trunk over weeks; he had increasing migrating pain located to joints and a slight feeling of systemic illness, but no fever. His blood tests were normal except for CRP 21 and ESR 25. We could not find any rheumatic or vasculitis marker, any recent viral infection or chest pathology on X-ray. His spleen was borderline large. MRI showed inhomogeneous marrow and lytic lesions. A bone marrow biopsy was performed and at the same time his skin biopsy from 2 weeks earlier was reviewed using immunohistochemistry. The diagnosis was blastic plasmacytoid dendritic cell neoplasm (BPDCN), an extremely rare leukemia. This is the first known case in Norway. He started NOPHO-2008 ALL extra high risk protocol, had possible eye involvement and therefore extra intrathecal cytostatics, and had a stem cell transplant 6 months after treatment started. He is now well without further treatment 16 months after transplant.