staghorn calculi are branched calculi that fill the entire or part of the renal pelvis and extend into the renal calices . if untreated or inadequately treated , they may lead to various complications such as deterioration of renal function and risk of developing urosepsis . in addition , chronic irritation , inflammation and infection from these stones can cause squamous metaplasia of the renal pelvis epithelium that may progress to squamous cell carcinoma . squamous cell carcinoma of the renal pelvis is a rare tumor , with a prevalence of < 1% of urinary tract neoplasms . here we demonstrate an older woman with staghorn calculi presenting with severe hypercalcemia caused by squamous cell carcinoma of the renal pelvis . a 79-year - old female presented with gradual deterioration of mental status for 1 month . for 2 months prior to admission , she had had intermittent right upper abdominal pain , vomiting , constipation , anorexia and significant weight loss . her medical conditions were hypertension and dyslipidemia , and she was receiving treatment with amlodipine and simvastatin . kidney , ureter and bladder ( kub ) x - ray visualized a large right staghorn stone ( fig . 1a ) , and a retrograde pyelogram showed right staghorn renal calculi with partial obstruction and left middle ureter stricture ( fig . a diuretic renal scan was interpreted as a nonfunctioning right kidney and fair renal function of the left kidney . serum blood urea nitrogen and creatinine were 52 mg / dl ( reference range 718 ) and 6.8 mg / dl ( reference range 0.671.17 ) , respectively . she was rehydrated with normal saline and then referred to our hospital for relief of left ureteric obstruction . on examination , the patient appeared lethargic and dehydrated . her blood pressure was 160/87 mm hg and her pulse rate was 93 beats / min . two lymph nodes , 0.7 and 1 cm in diameter , were palpated in the left supraclavicular area . she had nonpitting edema on both legs that was more pronounced on the right leg with the presence of homan 's sign . urinary examination showed a ph of 5 , white blood cells of 12/high - power field and red blood cells of 01 cells / high - power field . furthermore , blood chemistries revealed serum total calcium of 14.8 mg / dl ( reference range 8.510.1 ) , serum phosphorus of 3 mg / dl ( reference range 2.54.9 ) and serum creatinine of 2 mg / dl ( reference range 0.671.17 ) . serum intact parathyroid hormone ( pth ) was investigated and found to be 11.5 pg / ml ( reference range 1565 ) . in the settings of old age , weight loss and deep vein thrombosis , humoral hypercalcemia of malignancy was mostly suspected . unfortunately , we could not confirm the diagnosis with pth - related protein ( pth - rp ) due to test unavailability in our country . renal ultrasound visualized large right staghorn calculi and moderate left hydronephrosis with proximal hydroureter ( fig . doppler ultrasound showed acute extensive deep vein thrombosis of both legs along the external iliac vein , the common femoral vein , the proximal deep femoral vein to the popliteal vein . there was minimal right pleural effusion on chest x - ray , with no abnormal pulmonary nodules . in searching for the primary site of malignancy , histopathology was compatible with metastatic squamous cell carcinoma . computed tomography of the chest and abdomen showed an infiltrative tumor with extensive involvement of the right kidney , the right pelvocalyceal system , the right adrenal gland , the right lobe of the liver and the adjacent right hemidiaphragm and psoas muscle ( fig . there were inferior vena cava invasion and multiple metastases in both hepatic lobes and intra - abdominal lymph nodes . the final diagnosis was advanced - stage squamous cell carcinoma of the right renal pelvis . to rescue left kidney function , a left retrograde pyelogram with double j stent after restoration of volume status , serum creatinine levels decreased from 2.0 to 1.7 mg / dl . four days later , serum calcium level subsided to 10.16 mg / dl . it was decided that long - term therapy would be the best supportive care . the patient was discharged to a primary care hospital and passed away 1 month later . the tumor generally presents with abrupt onset , severe symptoms and high serum calcium concentration of > 14 mg / dl . even though various cells in the body have the potential to produce pth - rp , tumors that commonly produce pth - rp include squamous cell carcinomas of the head and neck , esophagus , cervix and lung ; adenocarcinomas of the breast and ovary and renal cell carcinoma . the definite diagnosis can be confirmed by detection of high serum pth - rp , but this is not necessary for diagnosis in most situations . squamous cell carcinoma of the renal pelvis is a very rare tumor , accounting for only 0.58.0% of malignant renal tumors [ 5 , 6 ] . the coexistence of renal calculi has been reported in 87100% of cases [ 6 , 8 , 9 ] . it has also been associated with tuberculosis , chronic pyelonephritis , radiation therapy , chronic rejection in a transplanted kidney , analgesic abuse with phenacetin , immunosuppression with azathioprine and previous percutaneous nephrolithotomy . staghorn calculi are usually composed of magnesium ammonium phosphate ( struvite ) and/or calcium carbonate apatite . cystine or uric acid mixed with other components can also grow in a staghorn configuration . infection stones because of the strong relation with urinary tract infection caused by urease - producing gram - negative bacteria , e.g. proteus , morganella and providencia spp . however , recent data found that 55% of cases with staghorn calculi were from metabolic stones , in particular of calcium phosphate composition . moreover , the most common component of staghorn calculi in patients in southern thailand was uric acid . left untreated , staghorn calculi may cause life - threatening sepsis and renal function impairment . over time , staghorn stones cause squamous metaplasia and dysplasia of the uroepithelium . therefore , most patients should require treatment of staghorn stones . the treatment options are medical therapy , surgery , percutaneous nephrolithotomy and shock wave lithotripsy . analysis of the composition of the stone and metabolic evaluation are essential for preventing recurrence [ 13 , 14 ] . increased fluid intake to achieve a urine output of > 2.5 l / day will decrease the risk of urinary supersaturation . early detection of the tumor by ultrasound would be difficult because the tumor appears as a nonspecific finding , such as a solid mass , calcification or hydronephrosis . as a result , a computed tomography scan may be an option for cancer detection , with better yield for diagnosis . findings of filling defect in the collecting system , delayed appearance of pyelogram or renal parenchymal thickening should be definitely considered as renal tumor . in conclusion , humoral hypercalcemia of malignancy mediated by pth - rp is an uncommon feature of the tumor . removal of the staghorn stone is necessary to eliminate infection and prevent squamous metaplasia of the renal epithelium . written informed consent was obtained from the next of kin for publication of this case report and the accompanying images . a copy of the written consent is available for review by the editor of this journal .
we report on a 79-year - old woman with staghorn calculi who presented with severe hypercalcemia . she was later found to have humoral hypercalcemia of malignancy caused by a rare tumor , squamous cell carcinoma of the renal pelvis . 
 chronic irritation , infection and inflammation from staghorn stones cause squamous metaplasia , leading to squamous cell carcinoma of the renal collecting system . 
 the prognosis is very poor , with a 5-year survival rate of < 10% . 
 this case highlights the importance of awareness of a very rare and aggressive carcinoma in a patient with long - standing nephrolithiasis .