Metastatic bone disease from an occult renal primary

Area of Science:

• Oncology
• Radiology
• Pathology

Background:

• Metastatic renal cell carcinoma (mRCC) commonly presents with symptoms related to primary tumor burden or distant metastases.
• Bone metastases are a frequent manifestation of advanced RCC, often indicating a poor prognosis.

Observation:

• A 71-year-old male presented with persistent shoulder pain, leading to imaging studies.
• Magnetic resonance imaging (MRI) revealed extensive lytic bone lesions, suggestive of metastatic disease.
• Comprehensive staging with CT and FDG-PET/CT failed to identify a primary tumor source.

Findings:

• The diagnosis of mRCC was confirmed through immunohistochemistry on biopsies of bone and liver lesions.
• This case represents an extremely rare scenario where the primary renal tumor was not identifiable at presentation.

Implications:

• This case underscores the importance of considering mRCC in the differential diagnosis of unexplained bone metastases, even without an apparent primary tumor.
• Advanced immunohistochemical analysis of metastatic tissue is crucial for accurate diagnosis in atypical presentations of renal cell carcinoma.
• Further research into the mechanisms underlying occult primary tumors in mRCC could improve diagnostic strategies.