Isolated peripheral neuropathy as an unusual presentation for an extramedullary relapse of acute leukemia

A 23-year-old man in remission from acute myeloblastic leukemia after allogeneic peripheral blood stem cell transplantation developed peripheral neuropathy presenting as sciatic and peroneal nerve deficits. Electrophysiological tests localized the lesions to the left sciatic and common peroneal nerve. Magnetic resonance imaging revealed nerve thickening and enhancement, while a positron emission tomography-computed tomography scan demonstrated increased fluorodeoxyglucose uptake tracking along the nerve, suggesting peripheral nerve infiltration. This report demonstrates an unusual presentation of acute leukemia relapse presenting as focal neuropathy. Neurology Asia 2014; 19(2) : 203 – 206 Address correspondence to: Yuncheng Wu, MD, PhD, Associate Professor of Neurology, Department of Neurology, Shanghai First People’s Hospital, Shanghai Jiao Tong University School of Medicine, No. 100, Haining Road, Shanghai 200080, P.R. China. Tel: 86-21-37798581, Fax: 86-21-63240825, Email: [email protected] INTRODUCTION Acute leukemia can involve the central nervous system (CNS) and rarely, the peripheral nervous system (PNS). In PNS involvement, common sites include cranial nerves and nerve roots; but isolated peripheral nerves are seldom directly affected by infiltration without also involving the epidura or leptomeninges. Here we report a case with left sciatic and peroneal neuropathy as the only manifestation of an acute monocytic leukemia relapse following allogeneic peripheral blood stem cell transplantation (allo-PBSCT). Positron emission tomography (PET) and gadolinium (Gd) -enhanced magnetic resonance imaging (MRI) are invaluable in confirming nerve invasion by leukemia. Clinicians should always include the focal infiltration of leukemia in the differential diagnosis when encountering patients with a history of leukemia.