Development of pulmonary metastasis after removal of the primary tumor: a case report of an adult mesoblastic nephroma and review of the literature

We report a rare adult case of mesoblastic nephroma with pulmonary metastasis. A 28-year-old man was referred to our hospital with a complaint of left flank pain and intermittent gross hematuria. A diagnosis of a left renal tumor was made after several radiographic examinations. But, a nodule was also detected in the lung by CT scan. We operated on him for left radical nephrectomy. On the basis of the histological analysis, we diagnosed it as adult mesoblastic nephroma (MN). Subsequently, he underwent follow-up at 25 months after the operation. Although there was no evidence of recurrence of the primary tumor lesion, the nodule in the left upper lobe was enlarged. Cutting needle core biopsy was therefore performed and the resultant data showed that the metastatic development of adult MN had occurred. We diagnosed the patient as having metastasis of cellular adult MN in the lung before the operation and postoperative metastatic progress. Local radiofrequency catheter ablation failed to treat the lung metastasis.