A 33-year-old man presented with left flank dull ache.
On the abdominal computed tomography, a solid renal mass in the upper portion of the left kidney was identified.
The mass was measured 2.8 cm × 2.8 cm × 2.5 cm in size, was well-defined.
The patient had no other abnormal findings, such as suspected distant metastasis or lymph node metastasis.
Radical nephrectomy was performed on 14/9/2005.
On gross examination, the nephrectomy specimen measured 11.5 cm × 6.5 cm × 4.5 cm and the tumor was a solid, grayish-brown mass measured 3.5 cm × 2.5 cm × 2.2 cm in size.
Histologic examination demonstrated trabecular and ribbonlike patterns with minimal fibrotic stroma.
The cytoplasm was granular and eosinophilic with uniform round to oval nuclei with finely stippled chromatin and inconspicuous nucleoli.
Mitoses were not found (0 per 10 high-power fields) on H&E stain.
The final pathologic examination revealed a well-differentiated neuroendocrine (carcinoid) tumor confined to the kidney (Fig.1).
Immunohistochemical stains demonstrated labeling with chromogranin, neuron-specific enolase and synaptophysin (Fig.2), and the proliferation index was less than 2 % as measured by immunohistochemistry for Ki-67.
Further radiation and chemotherapy were not received.
Nine years after radical nephrectomy, computed tomography of the abdomen demonstrated a 2 cm × 1.8 cm cyst mass in the right liver and multiple high density shadow in gallbladder.
No enlarged lymph nodes were found in the abdominal cavity.
Cholecystectomy and extirpation for hepatic cyst were performed by laparoscopy surgery.
Histologic examination demonstrated trabecular and glandlike growth (Fig.3), moderate and uniform nuclei and mitoses weren't found (0 per 10 high-power fields).
Advanced immunohistochemistry revealed that the lesion was positive for synaptophysin (Fig.4) and CD56, but negative for chromogranin and neuron-specific enolase.
These features are supported in a neuroendocrine tumor.
Due to the similar pathologic characteristics between the primary renal carcinoid tumor and liver tumor.
The final pathology report indicated a carcinoid tumor of the left kidney with liver metastasis.