LAUSR

A 71-year-old Japanese woman presented with a fever of 38°C and weight loss. The results of her blood analysis were as follows: white blood cell count 4 8 9 10/l (58% neutrophils, 21% lymphocytes, 20% monocytes); haemoglobin concentration 141 g/l; platelet count 252 9 10/l; lactate dehydrogenase 452 iu/l; and C-reactive protein 4 3 mg/l. Plasma macrophage colony-stimulating factor (M-CSF) levels were elevated to 1960 pg/ml (normal value <373 pg/ml). Positron emission tomography/computed tomography (PET/ CT) imaging showed intense 2-fluoro-2-deoxy-D-glucose (FDG) uptake by lymph nodes in the left cervical, paratracheal and mediastinum regions, plus multiple vertebrae, ribs, shoulder blade, ilium, ischium, pubis and thigh bone (top left). Biopsy of a lymph node from the left side of the neck demonstrated scattered mononuclear Hodgkin and multinuclear Reed-Sternberg (HRS) cells, with the background containing numerous small lymphocytes (top centre). Immunostaining of the HRS cells was positive for CD30 (top right) and M-CSF (bottom left), but negative for CD79a. Bone marrow biopsy of the iliac region, which showed intense FDG uptake on PET/CT, showed infiltration by HRS cells (bottom right). These findings were indicative of a diagnosis of lymphocyte-rich classical Hodgkin lymphoma (LRCHL), stage IVB, according to the World Health Organization classification and the Ann Arbor staging system. The patient was treated with 6 courses of ABVD (doxorubicin, bleomycin, vinblastine and dacarbazine). After this therapy, the clinical symptoms, lymphoma lesions and monocytosis disappeared, with a white blood cell count of 4 8 9 10/l (64% neutrophils, 27% lymphocytes, and 6 5% monocytes). This case illustrates advanced stage LRCHL with bone marrow involvement in which HRS cells immunostained for M-CSF and in which chemotherapy-induced reduction in tumour size was paralleled by a decrease in the monocyte count. Clinicians may misdiagnose patients with monocytosis as having an inflammatory or infectious condition rather than neoplastic disease. It is therefore important to recognize this paraneoplastic phenomenon associated with some cases of LRCHL. M-CSF could be used as a tumour marker with potential implications in diagnosis and treatment.