LAUSR

Dear Editor, A 56-year-old female farmer knocked her right knee against the ground and suffered from stinging pain, while she was working in a rice field. The next day, she developed a painful erythematous eruption on the right knee. She consulted a dermatologist and was diagnosed with cellulitis, and was treated with flomoxef antibiotic orally. However, on the following day, the right knee was still painfully inflamed, and she was transferred to a local hospital. On admission, she presented with an extensive cellulitis-like eruption on the right leg and mild fever. She had a history of sub-total gastrectomy, due to gastric cancer without chemotherapy 19 years ago. Her laboratory findings and clinical course are described in Fig. 1. A computed tomography or magnetic resonance image showed subcutaneous to fascia lesions without fluid formation and mild edematous swelling with multiple thrombophlebitis in the right leg. Intensive treatments, including administrations of meropenem, clindamycin, and daptomycin and two local skin debridements, seemed to transiently improve the skin lesions. Recurrent tissue cultures of the dissected skin lesions and her blood revealed no pathogens, including bacteria and fungi. However, the skin lesions were not remedied despite these intensive treatments, and therefore, the patient transferred to our hospital for further treatments and evaluations. In our hospital, once a re-debridement was performed, the inflamed skin lesion and laboratory data gradually improved without antibiotics, and she was discharged. However, 2 weeks later, she developed new erythematous and partially purpuric lesions with pain and edema on the contralateral left leg and pancytopenia (Fig. 1). These findings strongly suggested an undetected underlying systemic disease. A bone marrow examination revealed that she had acute myeloblastic leukemia (AML) with the chromosomal translocation t(6;9)(p23;q34), DEK-CAN and internal duplications of the FMS-like tyrosine kinase 3 (FLT/ITD). A skin biopsy showed the infiltration of neutrophils in the dermis and adipose tissue, superficial dermal edema, intact epidermis, and the absence of vasculitis or massive necrotic change, compatible with a diagnosis of giant cellulitis-like Sweet syndrome (SS) [1–3]. Chemotherapy with prednisolone and indomethacin relieved the skin lesions and thrombophlebitis (Fig. 1). SS sometimes appears as a paraneoplastic neutrophilic dermatosis in connection with malignancies, either before, during, or after the definite diagnosis [4]. Recently, six cases of giant cellulitis-like SS, characterized by relapsing widespread giant lesions with bullous appearances, have been reported [1], although this pathogenesis remains unknown. This new variant of SS is likely to be misdiagnosed as acute infectious cellulitis, when the skin lesions precede the discovery of an underlyingmalignancy. In this case, the skin lesions seemed to transiently respond to the intensive treatments, and the initialonset episode of the skin lesion and the late-onset of cytopenia without pathological cells in the peripheral blood might have postponed her precise diagnosis. We could not deny the possibility that the comorbidity of thrombophlebitis exacerbated and extended her skin lesions. In conclusion, this is the first reported case of giant cellulitis-like SS with AML carrying t(6;9), DEK-CAN and FLT/ITD duplications [5]. Clinicians Shuhei Okuyama and Katsushi Tajima contributed equally to this work.