Haemangioblastoma is a slowly growing, highly vascular solid mass of uncertain histogenesis, also known as capillary haemangioblastoma (1). It typically occurs within the central nervous system (CNS), predominantly in the cerebellum (2). Renal haemangioblastoma is an extremely uncommon disease with a poorly established diagnosis due to a lack of descriptions of typical symptoms. To the best of our knowledge, there are 6 cases reported previously (Table I) (3,4). In the present study, we report the case of a patient with haemangioblastoma involving the kidney, which may be mistaken for other renal tumours, in particular renal cell carcinoma (RCC). The study was approved by the ethics committee of Peking University Shenzhen Hospital, Shenzhen, China. Written informed patient consent was obtained from the patient.

A 61-year-old male, who was found to have a right renal tumour during a routine examination, was admitted to our department for further examination on April 20, 2011. The patient was asymptomatic with a normal appetite, no abdominal pain and no weight changes. The patient had no urinary, respiratory or cardiovascular symptoms, no constitutional symptoms and had not previously undergone surgery. His family history was unremarkable. Physical examination revealed a well-developed and well-nourished male. The patient was afebrile and had a pulse of 66 beats per min, temperature 36.7°C, blood pressure 120/60 mmHg and respiration 20 per min. The chest was clear to percussion and auscultation and no masses were palpable on abdominal examination.

Laboratory examination revealed that haemoglobin was 12.3 g/dl, white blood cell count was 7.21×10⁹/l, with 61.4% granulocytes. Glucose was 5.88 mmol/l, blood urea nitrogen was 8.25 mmol/l and serum creatinine was 82.2 μmol/l. Liver function tests and serum electrolytes were within normal limits. Urinalysis was unremarkable. Chest X-ray was normal. A non-contrast computed tomography (CT) scan of the kidneys revealed a 6.5×6.2-cm round hypodense mass [48.2–54.2 Hounsfield units (HU)] in the upper pole of the right kidney (Fig. 1A and B). A contrast-enhanced CT revealed a heterogeneously enhanced mass with a non-enhanced hypodense region in the centre (Fig. 1C and D).

A right radical nephrectomy was performed on April 25, 2011. Tumour invasion to the adjacent tissue was not observed. Grossly, the tumour was a solid and well-encapsulated mass 6.5 cm in diameter. Microscopic examination revealed polygonal cells diffusely positive for α-inhibin, neuron-specific enolase (NSE) and S100 and confirmed renal haemangioblastoma. There was no clinical evidence of von Hippel-Lindau (VHL) disease. Magnetic resonance imaging (MRI) revealed no other tumours.

The patient was discharged on the fifth postoperative day after an uncomplicated post-surgical recovery. No evidence of recurrence or residual disease appeared on CT scans at follow-up (1 year).

Capillary haemangioblastoma is a benign tumour of uncertain histogenesis that generally occurs in a relatively restricted area of the CNS (2). In microscopic views, the tumours may exhibit significant nuclear pleomorphism, mimicking carcinoma or other malignancies (1,2). A majority of cases arise sporadically, whereas 25% are a manifestation of VHL disease (5). This tumour typically occurs within the CNS, predominantly in the cerebellum (2). Haemangioblastoma has also been rarely reported in sites outside of the CNS, including peripheral nerves, liver, lung, pancreas, retroperitoneum, kidney, pancreas, bladder, soft tissues of the ankle and popliteal fossa and nasal skin, usually in the setting of known VHL disease (6).

There are only a few studies concerning sporadic haemangioblastoma occurring outside the central nervous system. Sporadic renal haemangioblastoma are extremely rare, with only 6 cases reported previously (3,4). We describe the 7th sporadic renal haemangioblastoma. The diagnosis in the present case was based on the presence of typical morphology and immunophenotype (S100⁺, NSE⁺, α-inhibin⁺) (5).

CT scanning, with and without the administration of contrast material, is necessary to take full advantage of the contrast enhancement characteristics of highly vascular renal parenchymal tumours. In general, any renal mass that enhances with intravenous administration of contrast material on CT scanning by more than 15 HU should be considered an RCC until proven otherwise (7). In this patient, a contrast-enhanced CT revealed a heterogeneously enhanced mass (more than 20 HU; Fig. 1). The mass was thus highly suggestive of RCC. Until now, characteristic imaging features of renal haemangioblastoma remained unknown (3,5).

Haemangioblastoma is likely to be an underrecognised tumour of the kidney as it mimics numerous tumour types morphologically and is usually not considered in the differential diagnosis (8). A correct diagnosis is important for patients as haemangioblastoma is a benign disease, unlike malignant RCC (3). It is not necessary for patients with sporadic renal haemangioblastoma to receive further treatment (e.g., molecular targeted therapy) and their follow-up is different from that of patients with RCC (3).

We report a solid lesion of the kidney found to be a sporadic renal haemangioblastoma. Our review of published studies revealed only 6 cases reported previously. Haemangioblastoma is likely to be an underrecognised tumour of the kidney, as it mimics a number of tumour types morphologically and is usually not considered in the differential diagnosis. A correct diagnosis is important to avoid overdiagnosis and unnecessary clinical treatment.