Clinical History:
- A 56-year-old man had a history of smoking 2 packs of cigarettes per day for the past 35 years. He has experienced back pain for the past 4 months. On physical examination there are no abnormal findings. Laboratory studies show Hgb 12.7 g/dL, Hct 38.0%, serum calcium 10.9 mg/dL, phosphorus 3.1 mg/dL, alkaline phosphatase 213 U/L, albumin 4.9 g/dL, and total protein 6.8 g/dL. A bone scan is performed. Three months later he experiences marked pelvic pain, and a radiograph (image 3.2) and a CT scan (image 3.3) reveal additional lesions, even though there was no history of trauma. A bone marrow biopsy is performed (image 3.4).
- What is the diagnosis?
This is a metastatic lesion, not a primary bone tumor. The lytic nature of the lesions and the clear cells seen microscopically are typical of renal cell carcinoma metastases. Multiple lesions (polyostotic lesions) suggest metastases. Overall, the most common malignancy involving bone in adults is metastatic carcinoma.
- From the history, what might have you suspected?
The smoking history suggests a lung primary. Lung, breast, kidney, and prostate primaries like to metastasize to bone. One clue in this case is the absence of a kidney (no excretion of the radionucleide), as seen on the nuclear medicine scan. The incidence of renal cell carcinoma is increased in smokers. Obviously, most metastatic bone lesions are seen in adults, and most occur in central locations (not in distal extremities).
- What descriptive name is given to the fracture in this case?
Such fractures produced by neoplasms are called "pathologic"
fractures.
- How would you describe the lesion seen on CT scan?
This is an osteolytic metastasis. Renal cell carcinomas often produce this pattern. Growth of the metastasis produces bone destruction, increasing the risk for fracture.
Further Clinical Histories:
- A 52-year-old woman experienced a 6 kg weight loss over the last 6 months of life. She had a left mastectomy with lymph node sampling performed 5 years before for infiltrating ductal carcinoma that was estrogen receptor positive. She had back pain and shoulder pain that was dull but constant. At autopsy, the gross (image 3.5) and microscopic (image 3.6) appearances of one of her lesions are seen. Compare this with the lesion seen at autopsy in a 45-year-old man (image 3.7). A different pattern is seen in the CT scan of a 70-year-old man (image 3.8).
- What is the diagnosis for the 52-year-old woman?
This is metastatic breast carcinoma. Growth of the tumor can produce reactive new bone that appears denser and brighter on radiographs.
- What is the diagnosis for the 45-year-old man?
The black colour is typical for metastatic melanoma. Melanomas tend to metastasize widely.
- How would you describe the lesions seen on CT in the 70-year-old man?
These are osteoblastic metastases in which considerable new reactive bone is being induced by the growth of the tumor. Prostatic adenocarcinomas can metastasize to bone and produce this pattern.
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