1. Introduction
Typical clinical features of hairy cell leukemia (HCL) are cytopenias
related to bone marrow infiltration and splenomegaly. Skeletal
localization is a rare but well-recognized complication, mostly
identified by painful osteolytic lesions in the proximal portions of
long bones, although bone presentations with exclusive bone pain and few
clinical and biological symptoms at presentation have been reported (1).
Unusual presentation may pose a significant diagnosis challenge in
routine practice. Only a few cases of HCL patients who have had a18F-FDG PET/CT have been published but all of them
showed hypermetabolic localizations (1). Here, we report two cases of
patients treated at the same medical center eight years apart from each
other, with singular presentation of HCL characterized by threatening
bone damage and lack or moderate bone marrow infiltration, and for whom18F-FDG PET/CT had an important role. The therapeutic
options combining cladribine (CDA) and rituximab (R) were very
effective, allowing durable complete remission (CR).