Aggressive renal tumour: squamous cell carcinoma with sarcomatoid differentiation
A multiphase CT scan again demonstrated gross right renal hydronephrosis with renal parenchymal atrophy and multiple right renal calculi (Fig. 1). The patient now consented to open right nephrectomy. The surgery was challenging, as the inflamed mass was very large and adherent; 2L of pus and numerous smaller hard masses and calculi were drained from the kidney to facilitate its removal. Despite the difficult procedure, she had a rapid and uneventful post‐operative recovery and was discharged home 5 days later.
Pathological macroscopic examination of the operative specimen showed a hydronephrotic kidney with gross pyonephrosis, marked cortical atrophy and an obstructing renal calculus at the PUJ. Histological examination unexpectedly showed urothelial squamous metaplasia of the pelvic urothelium with squamous cell carcinoma (SCC) in situ and free‐lying fragments of sarcomatoid tumour.
The sarcomatoid tumour was negative for five epithelial markers with only p63 being positive. Melanoma, smooth muscle, myoepithelial, urothelial, renal cell carcinoma and gastrointestinal stromal tumour (GIST) markers were negative. The vascular marker CD31 showed background staining. Given the clinical setting of long‐standing chronic inflammation and SCC in situ of the renal pelvis, together with the positive p63, the malignancy (Fig. 2) was favoured to represent sarcomatoid SCC of the renal pelvis.
Eight weeks later, the patient re‐presented with fever, severe epigastric pain and tachycardia. Repeat CT demonstrated an extensive, predominantly solid, lobulated mass (8.7 × 14.9 × 12.2 cm) within the right renal bed extending inferiorly involving the entire right paracolic gutter into the pelvis and several peritoneal nodules (Fig. 3). CT‐guided fine needle aspiration biopsy of the right abdominal mass found features of a poorly differentiated epithelioid and spindle cell malignancy. This specimen was compared with the previous right nephrectomy sarcomatoid SCC specimen and was of similar morphological appearance. A CT pulmonary angiogram and technetium medronic acid (99mTc) methyl diphosphonate whole‐body bone scan did not demonstrate evidence of metastatic disease. Given the aggressive nature of her disease, she underwent palliative radiotherapy for symptom control and died 3 months post nephrectomy.
Renal pelvic SCC is a rare malignancy, accounting for 0.5% of renal tumours.1 There are only two other reported cases of intraparenchymal renal SCC in the literature.2 Renal SCC is frequently associated with chronic inflammation or infection, hydronephrosis, chronic analgesic abuse and squamous metaplasia.5 Urolithiasis is a major risk factor, found in 18–100% of cases.6 The postulated mechanism is the development of metaplasia secondary to chronic inflammation.
The prognosis of renal SCC is poor, with some case series reporting a median survival time of 3.5 months.4 Most reports of renal pelvic SCC present at an advanced, palliative stage.7 However, stage for stage the prognosis is not different between patients with urothelial carcinoma and SCC of the renal pelvis and ureter.8 Often, these malignancies present when the tumours are already invasive, at an advanced stage, at a time when they are incurable. To improve the poor prognosis of advanced stage SCC and upper urinary tract urothelial carcinoma, new treatment modalities are urgently required.