Clear cell sarcoma of the kidney.SC Sharma, PA Menon
Department of Paediatric Surgery, Sir Padampat Mother and Child Health Institute, SMS Medical College, Jaipur - 302 004, India. , India
Correspondence Address: Source of Support: None, Conflict of Interest: None PMID: 11832627
Source of Support: None, Conflict of Interest: None
Keywords: Case Report, Diagnosis, Differential, Human, Infant, Kidney Neoplasms, pathology,surgery,Male, Sarcoma, Clear Cell, pathology,surgery,
A year-old male infant presented with a 15 days history of abdominal distension and constipation. There was no history of vomiting, loss of weight or haematuria. On examination, the patient had pallor and a systolic blood pressure of 84 mmHg. The abdomen was distended and a firm, non-tender swelling was found occupying the right hypochondrial and lumbar regions. Blood and urine investigations including 24 hours vanillyl mandelic acid and chest radiograph were within normal limits. Ultrasonography showed a 12.3 x 8.7 cm round heterogeneous mass arising from the superolateral aspect of the right kidney.
At laparotomy, the tumour was removed en mass along with the right ureter. The tumour was pushing the liver medially and was superficially adherent to the right dome of diaphragm, under surface of the right lobe of liver and the inferior vena cava. There were two lymphnodes over the renal hilum which were excised. Post-operatively, he was started on etoposide and ifosfamide. The histopathology was initially given as malignant round cell tumour of uncertain histogenesis. Later, on further sectioning, it was confirmed as clear cell sarcoma of kidney [Figure - 1], [Figure - 2]. At follow-up after six months, the child was doing well. A bone scan performed at this time was normal.
Clear cell sarcoma of the kidney (CCSK) comprises 4% of all primary renal tumours and due to several distinctive features has been classified separately from Wilms tumour. Unlike Wilms tumour it is not associated with hemihypertrophy and sporadic aniridia. It has a propensity to metastasise to bone giving it the name “bone metastasising renal tumour of childhood”. Late onset of first relapse is a distinctive feature even in stage-I tumours and regular post-operative follow up is essential.
Non-Wilms renal tumours account for less than 10% of primary renal neoplasms of childhood. CCSK has a peak incidence between 3 and 5 years with a male - female ratio of 2:1.
Grossly, CCSK tumours are large with a mucoid texture, foci of necrosis and prominent cyst formation. They are unilateral and unicentric, often arising from the medullary or central regions of the kidney. Numerous vesicles, often appearing intracytoplasmic, is a conspicuous feature and is the basis for the term clear cell sarcoma [Figure - 1]. The tumour kidney junction is sharp and is another characteristic feature. However at the periphery there is entrapment of individual nephrons or collecting ducts characterizing its infiltrative nature. Most tumours have a “classic pattern” where the tumour appears monomorphous with cords or nests of 6 to 10 cells separated by evenly dispersed small vascular septa [Figure - 2]. Other histological types include variant, epitheloid, spindled, sclerosing, myxoid, cystic, palisading, sinusoidal and anaplastic patterns. In most cases more than one pattern is seen. However any region of unequivocal nephroblastoma excludes the diagnosis of CCSK.
A 17% incidence of bone metastases has been noted in CCSK tumours in the National Wilms Tumour Study (NWTS) experience compared with less than 2% with Wilms tumour. Other commonly observed metastatic sites are brain, regional lymph nodes, lungs, liver and soft tissue. In contrast to Wilms tumour, relapses after intervals as long as 5 years have been documented.
Unlike Wilms tumour, genetic studies on CCSK have not shown any consistent findings. In a study of CCSK by comparative genomic hybridisation, one of the four cases studied had gain of the entire 1q chromosome arm and a small gain of the terminal end of 11q. Studies based on immunohistochemical demonstration of mutant p53 proteins have suggested that alterations in the p53 tumour suppressor gene do occur in CCSK.
A comparative study of patients treated on NWTS-1, NWTS-2 and NWTS-3 showed that addition of doxorubicin to the combination of vincristine (VCR) and actinomycin D improved the 6 year relapse free survival rate of children with CCSK.
In the ongoing NWTS-5 protocols, CCSK at all stages is treated with radical nephrectomy followed by chemotherapy with VCR, cyclophosphamide, doxorubicin and etoposide for 24 weeks and radiotherapy. Overall survival is 69%. Multivariate analysis has shown 4 independent prognostic factors: treatment with doxorubicin, stage, age at diagnosis and tumour necrosis.
Management of CCSK requires awareness and aggressive surgical approach followed by chemotherapy and radiotherapy as per NWTS protocols. Long term follow up is essential because of late relapses even in stage 1 tumours.
[Figure - 1], [Figure - 2]