The Risk of Misdiagnosing the Primary Site Responsible for Bone Metastases in Patients With Chronic Lymphocytic Leukemia and a Second Primary Carcinoma.

Chronic lymphocytic leukemia (CLL) is a common malignancy which may coexist with other primary cancers. CLL is rarely the cause of solitary bone lesions; such lesions in the context of CLL are believed to result from either Richter's transformation or metastasis from another primary malignancy. Renal cell carcinoma (RCC), on the other hand, is a malignancy which frequently metastasizes to bone and may cause an osteolytic solitary bone lesion. The origin of a solitary bone lesion in a patient with multiple potential primary malignancies has prognostic implications and affects treatment protocol, and as such must be diagnosed accurately. We describe a patient with CLL and a history of RCC who is found to have an incidental solitary bone lesion of the T11 vertebra. After two separate CT-guided biopsies revealed various lymphoid cell predominance and no evidence of RCC, treatment with low dose external beam radiation therapy (EBRT) was employed. Post-therapy MRI showed further propagation of the lesion. Surgical corpectomy was subsequently performed and postoperative pathology of the lesion was consistent with RCC. The patient was treated with bisphosphonates and a higher dose of EBRT. Our case illustrates the importance of surgical excisional biopsy for accurately diagnosing the primary source metastatic to the bone in a patient with CLL and another potential primary cancer.