د.أحمد تركي
BENIGN TUMOR OF THE KIDNEY
RENAL ADENOMA:
Is the most common benign tumor of the kidney , they are typically small , well differentiated glandular tumor of renal cortex , it is asyptomatic and usually identified incidentally .
It is indistinguishable from renal cell carcinoma and we consider it as pre malignant early stage of renal carcinoma growth , currently the seperation is based predominantly on the size of the lesion , tumor less than 3 cm are called adenoma and larger one are called carcinoma .
RENAL ONCOCYTOMA:
It has spectrum of behaviour ranging from benign to malignant , it represent 3_5% of renal tumor , men affected more than women .
The diagnosis of the oncocytoma is predominantly pathologic because there are no reliable distinguishing clinical features.
Patient may present as gross hematuria or flank pain , have typical gross appearance that differ from the typical gross appearance of the RCC , microscopically it composed of large epithelial cells called oncocytes.
Although oncocytoma may present as (spooke wheel ) appearance of tumor areterioles by angiography but this is rare and the differentiation from renal carcinoma only by the pathological study.
Treratmentis by the open or laproscopic partial or radical nephrectomy .
ANGIOMYOLIPOMA:
It is rae , present in two distinct types :
Sporadic: (80)% are more commonly unilateral , right sided(two third of cases), more common in female .
Familial:that are associated with tuberous sclerosis (20%)which is bilateral and asymptomatic ,tuberous sclerosis is a familial inherited disorder comprising adenoma sebacum , mental retardation and epilepsy.
Diagnosis:
Depend on US and the CT scan which are frequently diagnosed lesion with hight lipid content such as angiomyolipoma which contain mature fat cellc , smooth muscle and blood vessels.
5% of the cases can present with spontanous hemmorhage into the retroperitoneum.
Treatment :
Depend on the size and the symptom , if tumor less than 4cm or if the tumor more than 4cm without symptoms , the treatment by the follow up only.
Tumor more than 4cm with moderate to severe symptoms should undergo arterial embolization or nephron sparing surgery .
Other benign renal tumor leiomyoma , lipoma and hemengioma.
RENAL CELL CARCINOMA
EPIDEMIOLOGY:
It account 2.5% of adult cancer , 85% of primary malignant renal tumor is the RCC, male to female ratio is 2:1 , the highest incidence in Scandinavian , most cases are sporadic , heredietery RCC is assiciated with Von _Hippel_Lindau disease and less commonly with the tuberous sclerosis(TSC).
ETIOLOGY:
Many etiological factors had been suggested :
.autosomal dominant gene in the chromosome 3 (heredietery).
.the strongest risk factor is tobbaco use (two fold increase relative risk factor).
.occupational exposure ex: solvent, asbestose…ect.
.acquired renal cystic disease in dialysis patient.
PATHOLOGY:
Commonly arise from the proximal convoluted tubules, occur equally in both side , more common in the upper pole than the lower pole .
MACRSCOPICALLY:
Moderate tumor size are spherical and often occupy one of the poles of the kidney , the cut surface is usually yellowish (high lipid content )or dull white , semitransparent with area of hemorrhage , the tumor often divided into lobules by fibrous septa some of which are hemorrhagic.
Large tumor are more irregular in shape with central hemorrhage.
MICROSCOPICALLY:
The orgion of the RCC from the proximal tubular epithelium , the cells are either clear or granular , the growth pattern is either solid or tubular but sometimes all types and cells are mixed , the clear cell type are better.
HISTOLOGICAL CLASSIFICATION OF THE RCC:
.conventional type (80%): arise from the PCT either clear cell contain (glycogen, cholesterol) in its cytoplasm or granular (eosinophilic cytoplasm and mitochondria).
.papillary (10_15) %: tubular or solid variant, 40% multifocal.
.chromophobe(5%): arise from the cortical portion of the collecting duct.
.collecting duct: rare, poor prognosis.
.sracomatoid type: rare, infiltrative, poorly differentiated variant.
SPREAD:
. Direct extension into the adrenal, renal vein, IVC and right atrium.
.lymphatic: into the hillar and para aortic lymph nodes.
. haematogenous : lung , bone , liver and brain .
STAGING:
Stage 1: tumor within the renal parenchyma , no invasion of the renal capsule .
Stage 2: invade the perinephric fat but not the Gerota fascia.
Stage 3:
a. invade the renal vein or the IVC.
b.involovement of the regional lymph node.
c.involvement of the both the regional and local blood vessels.
Stage 4:
a. involvement of the adjacent organ (other than the adrenal gland ).
b. distant metastasis(lung , liver and bone).
CLINICAL FEATURE:
More than 50% of the RCC are now detected incidentally on abdominal imaging, carried out to investigate unrelated symptoms.
50% of patients present with hematuria , 40% with lion pain , 30% of patients notice mass and 25% have symptoms and signs of metastatic diseaase include bone pain , night sweats and pyrexia …ect.
Less than 10% exhibit the classic traid of hematuria , pain and abdominal mass , less common presenting features include acute varicocele due to obstruction of testicular vein by tumor .
Paraneoplastic syndrom due to ectopic hormone secretion by tumor occur in 30% of the cases which includes:
a.hypertension: occur due to overproduction of the renin by tumor , usually refractory to the hypertensive medication but may response to the nephrectomy.
b.hypercalcemia : due to production of the parathyroid hormone like peptide or osteoplastic activating factor by the tumor.
c.erythrocytosis.
d.stauffer syndrom: reversible hepatic dysfunction in the absence of metastasis , due to production of macrophage colony stimulating factor, prsence of stauffer syndrom not mean poor prognosis , it usually resolve after radical nephrectomy .
IMAGING:
.intravenous pyelography (IVP): finding of the RCC are non specific and include mass effect on the collecting system , so it may appear as distorsion of the calyx , narrow or elongated calyces.
.Renal ultrasonography: US is used to distinguish cystic from solid renal masses. A classic cyst will be smooth with definite border of impereceptible thickness so if the mass solid and unhomogenous texture it possibly tumor .
.CT scan: CT scan of the abdomen and pelvis may be performed with or without the injection of the contrast material ,CT is also an excellent staging modality and provide superiour data on lymph node involovement , perinephric extension and renal vein and vena caval involvement .
.MRI: this modality mostly effective in demonstarting the presence and extent of renal vein and vena caval involvement .
.ANGIOGRAPHY: classic angiography is replaced by magnetic resonance angiography or 3D CT angiography in the preoperative planning for surgery on solitary kidney or before partial nephrectomy .
DIFFERENTIAL DIAGNOSIS:
. renal cyst.
. renal adenoma.
. hydronephrosis and pyelonephritis especially if the kidney is not fuctioning .
. polycystic kidney disease , IVP will differentiate .
. T.B abscess and calcification .
TREATMENT:
Localized disease by radical nephrectomy which include (kidney and its enveloping fascia including ipsilateral adrenal gland and proximal half of the ureter and the regional lymph node to the level of the ureteric transection ),this choice is very promissing in the localized disease.
In advance disease: palliative surgery (radical nephrectomy ) in case of the advanced disease with severe hemorrhage and remitting pain and also can be used in those with RCC and solitary lung nodule .
Radiotherpy : in which its effect in the RCC is poor because RCC is radioresisitant .
Chemotherapy : RCC is the most chemoresisitant epithelial tumor .
Hormonal therapy : in which its effect is breif and partial like progestational agent , androgen and antiestrogen.
Immunotherapy :some RCC resolve spontaneously althought it is rare , but no specific cause exist , many believe its due to immunological response ex: interferone alpha , beta and gamma.
PROGNOSIS:
Depend on stage of the disease , 5yrs survival for stage 1 is 91_96%.
WILMS TUMOR (NEPHROBLASTOMA)
The most common solid tumor of the childhood, accounting 5%of childhood cancers. The peak age of presentation is the 3rd years of life. Tumor commonly unicenteric, 5% of the cases bilateral. Wilms tumor in familial and non familial forms. The national wilms tumor study (NWTS) group documented the occurrence of the familial form in 1% of the cases.
10% of the cases of patients with wilms tumor associated congenital malformation like WAGRE (Wilms, Aniridia, Genitourinary malformation, Mental Retardation, over growth syndrome), some of these genetic syndroms are associated with alteration in the WT1 gene.
ETIOLOGY:
The pathogenesis of the sporadic form of wilms tumor result from two postzygotic mutations in a single cell , in contrast , the familial form of the disease arise after one prezygotic mutation and a subsequent postzygotic event . karyotypic analyses of wilms tumor patient with various congenital malformation identify a region on short arm of chromosome 11 (11p13).
PATHOGENESIS AND PATHOLOGY:
The typical wilms tumor consists of blastemal, epithelial and stromal element in varying proportions.
The NWTS correlate pathological specimens with clinical outcome and divide various histological features into favorable and unfavorable prognostic group , the unfavorable subgroup include tumor that contain element of anplastic cells or two other neoplastic entities (Clear cell sarcoma and rhabdoid tumor ).
Grossly wilms tumor large, multilobulated and gray in color.
Tumor dissemination can occur by direct extension through renal capsule, or hematogenously via the renal vein or vena cava or via lymphatic.
TUMOR STAGING:
STAGE 1: tumor limited to the kidney and completely excised , no penetration of the renal capsule , tumor was not ruptured, no residual tumor beyond the margin of resection .
STAGE 2: tumor extend beyond the kidney but is completely removed, there is either penetration through the outer surface of the renal capsule , biopsy of the tumor before removal or spillage of the tumor locally during removal , there is no residual apparent at or beyond margin of excision and no lymph node involvement .
STAGE 3: residual non hematogenous tumor confined to the abdomen, any one or more of the following :
a. regional lymph node involvement.
b.diffuse peritoneal contamination by the tumor.
c.implant is found on the peritoneal surface.
d.tumor extends beyond the surgical margin.
e.tumor is not completely resectable because of the local infiltration into vital structure.
f.tumor spill not confined to the flank occur either before or during surgery.
g.transected tumor thrombus.
STAGE 4: hematogenous metastasis into lung, liver, bone ….ect.
STAGE 5: bilateral renal involvement.
CLINICAL FINDING
Symptom and sign:
The diagnosis of wilms tumor is most commonly made after discovery of an asymptomatic mass by a family member or physician during routine physical examination, common symptom at presentation
Abdominal pain, distension, fever, hematuria, hypertension is seen in 25-60% of cases.
LAB ANALYSIS:
GUE may show hematuria.
X-RAY IMAGING:
Abdominal US and CT scanning are performed initially to evaluate the mass .CT of the abdomen is performed with suspected wilms tumor and provide information regarding tumor extension, contralateral kidney status and the presence of regional lymphadenopathy.
MRI can also provide information in defining the extent of the tumor thrombus into IVC.
DIFFERENTIAL DIAGNOSIS
Hydronephrosis, cystic kidney, neuroblastoma, mesoblastic nephroma.
TREATMENT
Surgical measure:
Patient with unilateral kidney involvement do radical nephrectomy via transabdominal incision , retroperitoneal L.N dissection is not proven , tumor extend into IVC should be removed , excision of tumor extending into adjacent structure can be attempted if feasible , complete excision of tumor will decrease the amount of additional chemotherapy .
Child with bilateral renal involvement if with favorable histology can be managed by preoperative chemotherapy followed by renal sparing surgery , patient with unfavorable histology managed by aggressive surgery followed by chemotherapy and radiotherapy .
Chemotherapy
Wilms tumor recognized as chemosensative neoplasm.
Stage 1 (favorable and unfavorable), stage (favorable) need surgical resection and adjuvant chemotherapy without radiotherapy.
Stage3 and stage 4(favorable) need surgical resection, adjuvant chemotherapy and radiotherapy.
Stage 2-4 (unfavorable) need surgical resection, salvage chemotherapy and radiotherapy.
Bilateral disease (stage 5) need neoadjuvent chemotherapy and renal sparing surgery may be attempted but failure rate is high.