2. First case
The first case was a 59-year-old woman in 2012 with no past history, who presented with a painful right frontal tumefaction above the eyebrow. No growth bone or other abnormality was observed at the radiography. The scan showed a frontal anterior right tissue process up to the external part of the right frontal sinus and a lytic bone lesion beginning at the right orbit roof. The biopsy of the frontal lesion was inconclusive and suggested only a chronic lymphoproliferative disorder (CLPD) without further clarification. Proofreading of the frontal bone biopsy confirmed a bone localization of HCL with a BRAFV600E mutation positive (mutation identified in 70-100% of typical HCL cases) (2). The bone marrow biopsy revealed moderate infiltration by hairy cells expressing DBA44, cycline D1 and CD20 as well. The markers of T-lymphoproliferation disorders and extramedullary plasmocytoma were negative. The bone marrow aspirate showed a smear of medium richness on which the different myeloid cell lines were correctly represented without morphological abnormalities. No excess of blasts was observed, despite the presence of medium-sized lymphoid cells with basophil cytoplasm, and often with “shredded” appearance and circular and reniform nucleus with the chromatin unpacked. This confirmed the presence of around 6% of lymphoid cells whose cytological appearance suggested hairy cells. The phenotype was compatible to hairy cells CD19+ monotypic kappa of moderate intensity CD5- CD10- CD20+ high CD22+ high CD79b+ CD23- FMC7- CD38+ CD43- CD44+ IgG- IgM+ IgD- CD11c+ CD25+ CD103+ CD123+. The immunological score of HCL was 4/4, excluding a variant presentation. In order to assess the extension consecutive to the histology of the frontal bone lesion, 18F-FDG PET/CT was carried out. Three bone hypermetabolisms were reported: the known frontal bone lesion, one on the right semi-sacrum and the third on the hipbone, near the sacroiliac joint. The body scan did not identify focal lesion or lytic bone lesion at the hipbone but rather a bone densification, and no tumor syndrome was described. The patient was symptomatic only on the frontal lesion. The complete blood count was normal except for minimal thrombocytopenia: white blood cells at 4.8x109/L composed of 3.07x109neutrophils/L, 1.58x109 lymphocytes/L and 0.1x109 monocytes/L, hemoglobin was 14,2g/dL and platelets were at 148x109/L (lower limit at 150x109/L).
Because of long initial diagnostic wandering and the emergency of a treatment required in fear of a rapid progression of the orbit roof osteolytic lesion in case of diffuse large cell lymphoma, two cycles of CEP (cyclophosphamide, etoposide, prednisolone) were administered with no clinical benefit observed. As soon as the final histology of the bone marrow biopsy was received, the standard first-line treatment by purine analog, cladribine (CDA), was initiated.
Two months after the treatment, neither symptom nor pain, was reported by the patient. A complete response (CR) was obtained on both medical examination, blood count and scan. Six months after the treatment, the18F-FDG PET/CT done described a disappearance of hypermetabolisms on the right frontal bone, and of the sacrum and right hip bone at pelvic girdle. However, the bone marrow aspirate evaluation done at the 6-month treatment evaluation showed normal bone marrow cytology without lymphoid cells but also minimal residual disease of hairy cells of 0.3% of bone marrow cells. A total of four weekly rituximab was subsequently administered. With a follow-up of eight years after the treatment, no objective relapse had occurred.