A 49-year-old male was presented at our department with lower back pain and walking instability for the last few days. The patient suffered from end-stage renal disease on dialysis for the last 15 years and had a history of successful renal transplantation about 25 years ago. The initial renal insufficiency resulted from a chronic glomerulonephritis and the allograft was rejected 9 years after transplantation due to the same underlying condition. Furthermore, about 2 years ago, he underwent bilateral nephrectomy for solid tumorous masses in both nonfunctioning kidneys. The histologic examination revealed, bilaterally at that time, type 1 papillary renal cell carcinoma (pT1aN0M0, Fuhrman grade II, in sano resection). Additionally, the nonfunctioning transplant kidney was removed about 6 months ago due to recurrent episodes of macrohaematuria, without evidence for a malign tumour. At that time, there were no signs for a metastatic disease.\nAt current presentation, the performed magnetic resonance imaging (MRI) of the spine showed a pathologic facture at the right side of the first and second lumbar vertebral body () from a metastatic solid mass, as well as multiple osteolytic metastases from 7th cervical to 2nd lumbar vertebra. A staging computed tomography (CT) of the thorax and abdomen showed further osseous osteolytic metastatic lesions at the sternum, both scapulae, the bone pelvis, and the left proximal femoral bone. The performed biopsy of the osteolytic metastatic lesion at the second lumbar vertebra revealed a metastatic, mucin-poor variant, of a mucinous tubular and spindle cell carcinoma of the kidney (). A thorough reexamination of the old nephrectomy specimens showed that the tumour of the right kidney was also a mucin-poor variant of a MTSCC of the kidney, while the tumour of the left kidney was confirmed as a papillary RCC.\nHistologically, both the biopsy sample and the nephrectomy-specimen of the right kidney showed a renal cell tumour with a spindle cell component, as well as tubular and papillary parts without any clear cells. Both spindle and tubular-papillary parts were delimited by a basal membrane, forming a ball-shaped, epithelial tumour-growth pattern with spindled nuclear morphology, which did not match a sarcomatoid differentiation. Immunohistochemically, the tumour was negative for desmin and actin and S100 protein, as well as for HMB45, MITF1, MART1, and SOX-10. A positive reaction to Racemase (AMARC), PAX-8, and RCC was found, with focal positivity for CD10. Pan-Cytokeratin (AE1/AE3) and CK7 were negative except from the papillary parts. The Ki67 stain showed focal proliferation rates up to 30%. Furthermore, no mucoid interstitial matrix was found with H&E stain. Only with Alcian blue staining, <1% mucin in cellular areas was observed.\nAccording to our interdisciplinary tumour conference board's recommendation, the patient followed a systemic treatment with pazopanib and focal radiotherapy to lumbar and cervical vertebrae metastases. In further follow-up, irrespective of the started treatment, the tumour spread rapidly and after three months the patient presented with additional hepatic and pulmonary metastases. The patient finally succumbed to the disease a few months later.
A 52-year-old man was referred to our hospital because of a growing left renal tumor. A contrast-enhanced CT scan revealed the presence of a 93-mm tumor in the upper pole of the left kidney (Fig. a,b) with tumor thrombus observed in the left renal vein (Fig. c). The tumor was gradually enhanced from the corticomedullary phase to the excretory phase. Enlarged lymph nodes were present at the left external iliac lesion; they were extra-regional lymph nodes and no other distant metastasis was observed (Fig. d). We diagnosed him as having left RCC classified as cT3aN0M1.\nOpen radical nephrectomy and dissection of left-sided pelvic lymph nodes were performed. The tumor and lymph nodes were examined macroscopically and microscopically. Macroscopically, a 80 × 80-mm, gray–whitish and solid tumor with necrotic tissue was located in the upper pole of the resected left kidney. Microscopically, the tumor consisted of a tubular and partly papillary structure (Fig. a). The neoplastic cells were cuboidal with eosinophilic cytoplasm. The Fuhrman nuclear grading system is used to describe the RMTSCC., This case was classified as Fuhrman nuclear grade 3 (Fig. b). The tumor was invaded into left renal vein, and metastatic lymph nodes were found at the left external iliac area (Fig. c). Fascicular growth with spindle cells and mucin stained by Alcian blue stain were found (Fig. a). Immunohistochemical findings showed the neoplastic cells to be diffusely positive for AMACR (Fig. b) and CK 7 (Fig. c). CD 10 was negative in the neoplastic cells (Fig. d). Although Ki-67 and p53 were negative in the neoplastic cells with low nuclear grade, they were positive in the neoplastic cells with high nuclear grade (Fig. e,f). We subsequently diagnosed him as having left RMTSCC classified as pT3aN0M1.\nThree months after nephrectomy, a PET-CT scan showed metastasis at the second lumbar vertebra with a maximum standard uptake value of 5.7 (data not shown). Six months after nephrectomy, vertebrectomy was performed for metastasis at the second lumbar vertebra. The pathological findings showed metastasis of the RMTSCC to the second lumbar vertebra. Nine months after nephrectomy, another PET-CT scan showed two 10-mm lymph nodes at the left internal iliac lesion with a maximum standard uptake value of 5.1 (data not shown). These were not regional lymph nodes of RCC, but he was not suffering from other causative diseases such as prostate or rectal cancer. Therefore, we diagnosed these lymph nodes as metastasis of RMTSCC. We are planning on administration of tyrosine kinase inhibitor.