Metastatic renal cell carcinoma of unknown primary site. Clinical follow-up

Renal cell cancer metastases without evidence of a primary tumor are extremely rare. These variants are usually showed as a spontaneous description of single clinical cases.

Aim. This contribution is a clinical follow-up of synchronous renal cell cancer metastases of unknown primary site.

Results. A 52-year-old patient U. with a history of increased blood pressure, up to 170/100 mmHg for the last 5 years, who had undergone many instrumental examinations, including ultrasound examination, because of this disease. The computed tomography of the abdomen showed a 49×75 mm heterogeneous tumor in the right adrenal gland in October 2017. The combined positron emission and X-ray computed tomography showed a 79×54×41 mm mass in the right adrenal gland, associated with elevated fluorodeoxyglucose metabolic activity SUVmax 7.25. Focal accumulation of the radiopharmaceutical SUVmax 4.31 in a 17×11×24 mm mass was detected in the space of bifurcation in the mediastinum. The lytic lesion (10×15 mm) was found in right superior L3 articular process. The patient underwent retroperitoneoscopic adrenalectomy and thoracoscopic removal of mediastinal tumor in November 2017 because of the oligometastatic nature of the process. The histological study identified clear-cell carcinoma with areas of papillary structure in the right adrenal gland. The immunohistochemical study showed carcinoma cells intensively expressing CD10, and some other cells – RCC. The immune phenotype of the tumor was identified as clear-cell renal cell carcinoma. The immunohistological and immunohistochemical analysis reviled the metastases of the same variant of renal cell carcinoma in one of 9 lymph nodes. The patient was treated with pazopanib. The primary renal tumor was not detected during the dynamic observation, including the application of annual combined positron emission and X-ray computed tomography. The patient is alive without disease progression with a follow-up of 32 months.

Conclusion. Metastases of clear-cell renal cell carcinoma, including adrenal gland, without evidence of a primary site are extremely rare. The main method of treatment is a combination of surgery and targeted therapy, providing long-term local control of the course of the disease.