“…Bone marrow involvement in anaplastic large cell lymphoma (ALCL) is detected in about 10–14% of cases using standard analyses(Le Deley et al , ; Brugieres et al , ), but its detection increases to 30% following staining for CD30+, epithelial membrane antigen (EMA) and/or anaplastic lymphoma kinase (ALK) on bone marrow biopsy specimens (Fraga et al , ) and reaches 50% at diagnosis with techniques such as qualitative or quantitative polymerase chain reaction (PCR) for NPM1‐ALK , designed to detect minimal disseminated disease (Mussolin et al , ; Damm‐Welk et al , ,b). On the contrary, massive bone marrow involvement is rare and only a few cases of ALCL with leukaemic presentation have previously been published in children and adults (Bayle et al , ; Lesesve et al , ; Onciu et al , ; Grewal et al , ; Takahashi et al , ; Nguyen et al , ; Gadage et al , ; Kolenova et al , ; He & Viswanatha, ; Imamura et al , ). Although the 2‐year overall survival rate is about 90% in ALK‐positive ALCL (Brugieres et al , ), the prognosis of leukaemic ALCL seems to be unfavorable (Bayle et al , ; Onciu et al , ; Grewal et al , ; Takahashi et al , ; Nguyen et al , ; Gadage et al , ).…”