Hairy cell leukaemia variant with periarticular joint infiltration and excellent radiotherapy response.

Hairy cell leukaemia (HCL) is rare, accounting for only 2% of leukaemias. An even more infrequent variant has been described, HCL-V. The clinicopathologic features of these two entities overlap significantly, although they differ in a number of aspects, including demographics and immunophenotype. In this report, we present the case of a man with HCL-V diagnosed 12 years previously, who is currently haematologically stable with an unusual complication of joint pain due to extensive bony expansion secondary to leukaemic infiltration, and atypical skeletal imaging. His painful joint disease responded dramatically to radiotherapy.

Primary psoas sarcoma causing malignant psoas syndrome: favourable response to radiotherapy.

Malignant psoas syndrome (MPS) is an uncommon condition first described by Stevens et al. MPS is caused by malignant infiltration of the psoas muscle and adjacent nerves and is characterised by (fixed) flexion deformity of the ipsilateral hip and proximal lumbosacral plexopathy. It has previously been described in relation to metastatic carcinoma, melanoma and liposarcoma, as well as non-Hodgkins lymphoma. We present the case of a 68-year-old woman with a sarcoma arising in the left psoas muscle at the level of L4 who presented with symptoms of MPS. To the authors' knowledge this is the first case of MPS arising from a primary sarcoma of the iliopsoas compartment. The patient underwent presurgical radiotherapy, with a significant improvement in pain control without an increase in analgesic medications. We discuss the aetiology of MPS and the role of radiotherapy in the treatment of this rare syndrome.