To the editor:
The development of tumors on horseshoe kidneys is very rare. The most frequent tumor in this setting is the renal cell carcinoma, a genitourinary neoplasm that is commonly accompanied by a paraneoplasic syndrome. Amyloidosis is one of the manifestations of this syndrome.
We present a 69 year-old woman with a history of hypothyroidism and horseshoe kidney, in which a hypernephroma developed (fig. 1). The disease was diagnosed in another department and the patient was scheduled for surgery. She came to the Emergency Room because of edemas and malaise and she was admitted to the hospital. The laboratory parameters were: hemoglobin 11,1.4 g/dL; normal MCV; prolonged coagulation times, creatinine 4.9 mg/dL; urea 142 mg/dL, total proteins 4.7 g/dL; calcium 8 mg/dL, mild metabolic acidosis; proteinuria > 4 g/24 hours, important hematuria and leukocyturia.
Renal failure and nephrotic syndrome persisted for several weeks. The intervention was postponed for one month because of paroxysmal atrial fibrillation. A right nephrectomy was performed, as the kidney was irrigated by three arteries. A wedge of the healthy kidney was taken for microscopic study. The pathological study confirmed the hypernephroma and disclosed the presence of AA amyloidosis AA in the contralateral kidney. The postoperative course was without complications, but the renal function kept on worsening. A few days later the patient had seizures and the cranial CT scan revealed hyperdense image in the right occipital lobule compatible with hemorrhage, without mass effect, which suggested the presence of an amyloid angiopathy.
The clinical picture evolved with increasing malaise, asthenia, anorexia, continuing vomiting and anemia. The patient presented an episode of melena and an urgent endoscopy was performed, which disclosed esophageal laceration, that was sclerosed with adrenalin. A clinical picture of high fever with pancytopenia developed and Streptococcus was isolated in the blood culture. The patient presented bleeding from a sacral ulceration and the surgical wound and died in a few hours.
The horseshoe kidney is a frequent fusion anomaly. The kidney is irrigated by one renal artery in one third of the cases. In the remaining cases, duplicated or even triplicated renal arteries can be found.1 Although the association with tumors is rare2, 3 some cases of hypernephroma have been reported, as well as of transitional cell carcinomas, squamous cell carcinoma, Wilms tumors, lymphomas, carcinoid tumors and sarcomas.4, 5
10%-40% of the patients with hypernephroma presents a paraneoplasic syndrome, with unspecific symptoms (fever, asthenia, weight loss) or biochemical and metabolic alterations (hypercalcemia, hepatic dysfunction, hypertension or, like the reported case, amyloidosis).6-10 The presence of a paraneoplasic syndrome does not mean that there is metastatic disease and, according to some authors, it does not mean a worse prognosis,6 although that was not the case in our patient.
The treatment of the renal cell carcinoma is always surgical, and consists in partial or total nephrectomy.11 It is important to be aware of the manifestations of the paraneoplasic syndrome, as they can constitute the clinical picture at presentation or in case of recurrence.6
