PMC3745271_01
(A) Radiograph of an antero-posterior view of the right wrist displays an osteolytic lesion and soft tissue with bulging contour and cortical breakdown in the distal ulna. (B) CT scans of the right wrist in bone window setting presenting a 2x2x4 cm sized soft tissue density bulging mass and cortical breakdown on the ventral-medial side of the distal ulna. This mass showed no periosteal reaction and no sclerotic rim. (C) Coronal contrast enhanced T1-weighted MRI after gadolinium administration showed a soft tissue bulging mass on the ventral-medial side of the distal ulna. (D) PET-CT fusion axial images show focal intense FDG uptake in right distal ulna suggesting malignancy. No other abnormal FDG uptake was found to suggest distant metastasis. (E) Light microscopy with H&E staining (x12.5) showed a mass-like lesion with ill-defined border (F) H&E staining (x200) revealed diffuse infiltration of mixed inflammatory cells, including neutrophils, small lymphocytes, and plasma cells admixed with aggregated foamy macrophages. The foamy macrophages had a distinct cytoplasmic border, abundant pale eosinophilic granular cytoplasm, and a small round nucleus.
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Plain radiography of the wrist revealed a bulging mass-like lesion located at the distal ulna with a round radiolucent lesion of the distal ulna, suggesting an osteolytic mass (Figure 1A). CT of the wrist showed a lobulated soft-tissue-density mass about 2x2x4 cm involving the ventral-medial side of the distal ulna, with a focal cortical defect of the bone (Figure 1B). T2-weighted image, and was strongly enhanced by gadolinium injection (Figure 1C). The lobulated contour, with the extending pattern of the lesion into the adjacent soft tissues and location of the lesion itself, suggested infection, but the adjacent bone marrow edema was relatively minimal. Therefore, a tumorous lesion, such as primary bone tumor, metastasis/myeloma, or lymphoproliferative disease (Castleman's disease), seemed more probable, and infection seemed less likely. The PET-CT also showed focal intense fludeoxyglucose (FDG) uptake in the distal part of right ulna, compatible with malignancy, with no other abnormal FDG uptakes to indicate metastasis (Figure 1D). The foamy macrophages had a distinct cytoplasmic border, abundant pale eosinophilic granular cytoplasm, and a small round nucleus (Figure 1E and 1F).