Mediastinal metastases - clear cell RCC

Case contributed by Bruno Di Muzio
Diagnosis certain

Presentation

Chest pain for investigation.

Patient Data

Age: 55 years
Gender: Male

CT Chest

ct

There are two superior mediastinal solid hypervascular masses. Also, a left lower lobe peripheral solid pulmonary nodule. In the abdomen, the absence of the left kidney is noted. 

CT guided FNA

ct

22G needle FNA was performed with a cytotechnologist present to confirm sample adequacy. 

Macroscopy: CT-guided FNA of mediastinal mass - 2 passes: 3 air-dried smears,  3 alcohol-fixed smears and cell block prepared. Cytologist in attendance.

Microscopy: Slides show blood and clusters of malignant tumor cells. These cells have large nuclei with prominent nucleoli and a large amount of pale to clear cytoplasm.

A cell block has been prepared of the tumor cells show positive staining for PAX8 and broad-spectrum cytokeratin, but do not stain with CD10. The findings are consistent with metastatic renal cell carcinoma.

Conclusion: Mediastinal mass, CT-guided FNA: Positive for malignancy. Features consistent with metastatic renal cell carcinoma.

Case Discussion

This case shows well-defined hypervascular anterior mediastinum masses in an adult patient with a previous medical history of left nephrectomy 5 years ago. The imaging features are not those of lymphoma, a thymic carcinoma would be unlikely to present as multiple hypervascular lesions such as these. The appearances are highly concerning for hypervascular metastases, likely from a renal cell carcinoma in this scenario. 

FNA was performed and confirmed metastases from clear cell renal cell carcinoma, which was further confirmed to be the primary tumor that led to a left nephrectomy.  

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