A 53-year-old man presented with repeated bilateral flank pain for 6 month, at first, the pain is subtle, without apparent cause or any other symptoms such as micturition, urgent emiction, fever or gross hematuria. Since rest can relieve the symptoms, the patient did not pay much attention to it. Five days before being admitted to Xiangya hospital, the patient went to local clinic for help because the pain in the low back increased with significant dysuria, catheterization was performed, the drainage was pink with blood clots in it, suggesting urinary system tumor.
After admitted for further treatment, the patient was inquired in detail and examined carefully. He was a farmer and owned no pets. He lived in the west of Hunan province and had not traveled outside China. He got married at 20 and has a daughter, his wife and daughter reported no severe or congenital disease. He drank alcohol occasionally and was a heavy smoker. He had a surgery of nasal polypectomy 5 years ago. He reported no weight loss, headache, chest pain or cough, and declined history of congenital disease, coronary heart disease, hypertension, hepatitis, tuberculosis, schistosoma exposure, toxic and radioactive substances exposure, trauma, transfusion or allergy.
On physical examination, the patient showed no fever, his heart rate was 104 beats per minute, blood pressure 143/108 mm Hg, and respiratory rate 20 breaths per minute. He was clear headed and not in agony. No purpura or ecchymosis was found on the skin. Bilateral renal percussive pain was presented with tenderness in the right but not the left, no tenderness in the ureteral and bladder zone.
Ultrasound revealed 2 similar protruding masses in bilateral kidneys, with mass sizes about 94 x 69 mm (lower left kidney), 81x80 mm (upper right kidney). Both masses were hybrid echoed under ultrasound (Fig. 1A and B), indicating a cystic-solid structure with septa inside. CDFI (color Doppler flow imaging) of the masses described above both showed low blood flow. Enlarged lymph nodes were observed around bilateral renal portals. MRI findings accord with the result of ultrasound, and the mass on the left kidney showed high signal inside (Fig. 1C and D), inferring hemorrhage or necrosis in the mass recently. The white blood cell count (WBC) increased to 13.4 x 109/L (reference range 3.5-9.5 x 109/L), alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA), cancer antigen 125 (CA125), cancer antigen 242 (CA242), and cytokeratin-19-fragment were negative for blood screening.
Treatment options and findings were discussed with the patient, and the decision was made to perform an exploratory operation. Because intraoperative biopsy reported malignancy, the mass in the left kidney was removed with an additional 5 mm clinical margin. The gross specimen revealed multiple cysts within the tumor, full of reddish brown matters inferring hemorrhage or necrosis, which accords with the blood clots in the drainage described above. The solid component lies in the border, about 3 x 2 x 1 cm in size, medium texture, and grayish yellow in the cut section.
Hematoxylin and eosin stain show that tumor cells are separated by collagenous fiber (Fig. 2A), in most area, the tumor cells form tubular structure with mucus accumulated within (Fig. 2B), in some area, the tumor cells form papillary structure (Fig. 2C) accompanied with typical high-grade "hobnail" like cells within the tubules. The tumor compressing and invading surrounding tissue is easy to be seen (Fig. 2D). In summary, it is classic morphology for CDC. The cells stained strongly positive for PAX8, GATA3, KSP (Fig. 2F-H), EMA, CK-pan, CK19 and negative for CD10, CK7, TTF-1, OCT3/4, 34betaE12. The proliferation rate ki67 is about 20% (focally, Fig. 2I), PAX8 and GATA3 double positive supported the diagnosis (the antibodies employed are listed in Table 1).
The postoperative period was uneventful, the symptom of dysuria disappeared 5 days after surgery. Without adjuvant treatment, the patient went home for recovery, a month later, the patient came back as told. Post-surgery PET-CT confirmed the mass on the left kidney is also a lesion of CDC, and suggested there were metastasis in lungs, bones and multiple sites of lymph nodes (Fig. 3). After consulting the department of oncology, we suggested the patient to consider getting chemotherapy, he refused and discharged. With telephone follow-up every 3 months, we were informed that the patient survived for only 7 months and his family refused autopsy.