Metanephric neoplasms in kidney tumors

These tumors were first described in 1980 by Pag`es Granier and French literature. Several reports of similar lesions described in a variety of names then arose and was confirmed as a distinct entity. Include metanephric adenoma (predominantly epithelial), metanephric adenofibroma and metanephric stromal tumor (gastrointestinal stromal tumor) which is a pediatric tumor identical to the stromal component of metanephric adenofibroma.

Most clinical and pathological features of metanephric adenoma outlined around mid-1990 in two large series. metanephric adenofibroma was identified then as a biphasic tumor with epithelial and stromal elements and occurs mainly in children and young adults. metanephric tumors as a group are highly cellular benign epithelial tumors, with a close relationship with the PT and conceptualized by some as the benign end, as opposed to a spectrum of tumors that also includes WT and its malignant counterpart.

Pathology

These tumors vary in diameter from 3-15 cm. They are usually single-center, clearly circumscribed without a capsule. The cut surface is gray to yellow with focal hemorrhage, cystic changes, and necroses are uncommon. Histologically composed of well-packed small, round acini. Half of the tumors containing papillary structures that resemble primitive glomeruli. Psammoma bodies are frequently present. No blast elements are present. The stroma may be discrete or edematous. The cells are generally cubic-like monotone, scant cytoplasm and small nuclei, uniform with inconspicuous nucleoli. metanephric adenofibroma is composed of nests of epithelial elements similar to metanephric adenoma included in the bands and sheets of fibroblast-like spindle cells.

The proportion of spindle cells and epithelial components in these tumors varies. metanephric stromal tumors, as its name implies, is very similar to the stromal component of metanephric adenofibroma. The immunohistochemical profile includes positive WT1 and CD56 and epithelial membrane antigen and CK7 negative. The differential diagnosis usually includes papillary renal cell carcinoma (PRCC) and epithelial predominant WT. PRCC is more common in men, tends to be multifocal, with a pseudocapsule, and a different immunohistochemical profile (WT-1 negative, EMA, and CK7 positive.)Epithelial predominant WT is usually seen in younger patients, with a pseudocapsule, and more atypical cells with abundant mitotic activity. Immunohistochemistry, metanephric tumors and WT share resemblance - both are positive for WT-1 antigen and negative for EMA and CK7. However, CD56 is positive in metanephric tumors and negative in WT.

Clinical Presentation

Metanephric adenoma can occur in children and adults, however, is predominant in the fifth and sixth decades of life, with a distinct female preponderance (ratio between women and men 2: 1). metanephric adenofibroma is usually seen in children and young adults aged 5 months to 36 years with a male preponderance. Metanephric stromal tumors are seen mainly in children, if adults rarely reported. These tumors as a group comprise less than 1% of renal cell neoplasms. Most of these cases are discovered incidentally during imaging studies and differential diagnosis of incidental hematuria.

Radiographically, the metanephric adenoma appears as a hypovascular tumor protruding extrarenally.When symptomatic, can cause abdominal pain and hematuria. Erythrocytosis has been reported in patients at presentation.

Treatment and Prognosis

These tumors are benign, with the exception of a few case reports in question. If the metanephric adenoma is suspected on clinical findings, it is important to obtain an intraoperative diagnosis in order to avoid excessive resection. Erythrocytosis associated with these tumors resolved after complete resection. No local recurrence or distant metastasis has been reported metanephric stromal tumors. WT has been reported to have emerged in metanephric adenofibroma and metanephric stromal tumor, indicating a possible common origin of these entities. Renal angiodysplasia associated with these injuries may cause morbidity secondary to vascular complications. Resection without adjuvant chemotherapy is the preferred modality of treatment.

Renal Medullary Carcinoma in kidney tumors

Renal medullary carcinoma was first described by Davis et al. as a sickle cell nephropathy and termed so because of its predominantly medullary location. Prior to this report, many of these tumors were probably mistakenly classified as CDCs due to their histological resemblance to the latter. In a literature review of renal medullary carcinoma by Dimashkieh et al.,hemoglobinopathy was found in 53 of the 55 cases (50 patients had hemoglobin AS, two patients had hemoglobin SC, and one patient had hemoglobin SS disease).

Pathology
Renal medullary carcinoma is a centrally located tumor with an infiltrative growth pattern similar to that of CDC. It is believed to arise from the epithelium of the distal portion of the collecting duct. The right kidney is involved three times more commonly than the left kidney, and the mean tumor size ranges from 4–12 cm (mean of 7 cm).

Renal medullary carcinomas are widely infiltrative, and have variable areas of hemorrhage and necrosis. Histologically, a variety of growth patterns have been described with reticular growth pattern and compact adenoid cystic morphology being the common features. Most renal medullary carcinomas have areas of poorly differentiated cells with solid sheets of tumor cells. The tumor cells contain vesicular or clear nuclei with prominent nucleoli and amphophilic cytoplasm, which can have a squamoid or rhabdoid quality. The tumor cells are usually high grade and as with CDC, there is often marked desmoplasia and inflammation.

The immunohistochemical profile is similar to CDC but can be helpful in distinguishing renal medullary carcinoma from other poorly differentiated kidney tumors. The clinical scenario is the key to diagnosing this rare neoplasm.

Clinical Presentation
Renal medullary carcinoma is a highly aggressive tumor that occurs almost exclusively in young people (mean age 22 years), predominantly males (male to female ratio 2 : 1) with sickle cell disease or trait. The common presenting symptoms are gross hematuria, abdominal/flank pain, or weight loss. Metastatic disease in the lymph nodes or distant organs such as the brain can also be the initial evidence of the tumor. Of the patients with adequate staging information available from the two largest case series, 18% had stage III disease and 82% had stage IV disease on presentation.

Treatment and Prognosis
Renal medullary carcinomas are now widely regarded as a highly aggressive variant of RCC, with an almost uniformly fatal outcome. The mean survival after surgery has been about 4 months. Strouse et al. have reported that only one of the over 80 reported patients is alive at 2 years. This patient had a small tumor (<2 cm) confined to the kidney at the time of resection. Chemotherapy has been shown to increase survival beyond 4 months in anecdotal reports, but with no reported long-term survivors. In this review of chemotherapy, of the 15 patients assessable for response, there was one complete response, two partial responses, one minor response, one stable disease and ten patients had progressive disease.

The most common chemotherapy regimen used was MVAC. Radiation therapy in an adjuvant or palliative role was disappointing. Immunotherapy in a few patients also had disappointing results. In healthy patients
with systemic disease, treatment plans similar to those for urothelial cancers and CDC, with combination chemotherapy consisting of cisplatin-gemcitabine or the MVAC regimen) appears to be a reasonable choice, but is unsupported by specific data. We are unaware of any collaborative clinical trials addressing this issue.

Carcinoma of the Bellini collecting duct in kidney tumors

CDC is a rare tumor cells derived from renal collecting ducts of Bellini, and has less than 1% renal malignancies. Reported by Mancilla-Jimenez et al. in its report on papillary tumors, the examination renal tissue distant from the tumor to appear, in some cases, atypical hyperplastic changes of collecting tubules.

This raised the possibility that some papillary tumors arose from distal tubular pithelium. Fleming and Lewi ago describe the detailed features of the CDC as pathological entity based on several case reports.

Pathology
This tumor is characterized by a core location, with a size ranging from 2 to 12 cm, the appearance of firm white-gray and irregular infiltrative edge. Grows radially from the renal hilum to invade the renal cortex, renal cap Sule, and the renal sinus. Histologically, an irregular pattern of growth embedded in a desmoplastic tubulopapillary stroma. The tubules are lined with cells with eosinophilic cytoplasm nail scarce. The cells display high-grade nuclei with brisk mitotic activity, and prominent nucleoli. Sometimes sarcomatoid changes or mucin can be seen. Molecular events and cytogenetic changes that contribute are not well characterized, and a different pattern has yet emerged. The immunohistochemical profile is variable, with generally positive for phytoagglutinins and high molecular weight cytokeratin, with coexpression of vimentin and negative for CD10 and villi.


Clinical Presentation
It is a very aggressive tumor, usually presenting at an advanced stage, with gross hematuria, abdominal pain / back pain and a flank mass. At diagnosis, they often have metastatic disease in the lung, liver, lymph nodes, bone, or adrenal gland. It is more common in men (ratio of about 2: 1) with a wide range of age groups (13-83 years with an
average 55 years). Computed tomography (CT), this tumor appears as a central mass arising infiltrating the preservation of the renal contour and minimal contrast enhancement. Patients may have generalized inflammatory symptoms secondary to the release of cytokines of the tumor and the inflammatory reaction associated with the tumor.

Treatment and Prognosis
The diagnosis of CDC is usually done after the operation, and unlike other radiological RCC is difficult and there is a low preoperative suspicion in view of the rarity of the disease. The prognosis is generally very poor with most patients with distant metastases developing rapidly, with a median survival of 22 months.

The role of nephrectomy has been the subject of debate due to frequent metastasis to the presentation. Radical nephrectomy in the context of metastasis CDC appears to be useful only for palliation. Based on the pathological, immunohistochemical and cytogenetic
similarity with urothelial (CTP), compared with conventional carcinomas clear cell RCC, the preferred approach in treatment of metastatic disease with chemotherapy has been in place for immunotherapy.

In the largest series reported Dimopoulos et al. subsequently reported the MD Anderson Cancer Center experience involving 12 patients with CDC treated from 1980-90. Seven of eight patients with metastatic disease were treated with different combinations of chemotherapy with doxorubicin and cisplatin, methotrexate; vinblastine (MVAC) regimen is the most common. Only one patient achieved a minor response lasting 5 months. Six patients were treated with a combination of interleukin-2 and IFN-α with a response in a patient. Peyromaure et al. reported two complete responses with cisplatin and gemcitabine combination chemotherapy, which lasted 9 and 27 months.

Radiotherapy in this series appeared to have minimal benefit for local recurrence. Chao et al. a review noted that some patients with regional nodal disease without distant etastases have long-term disease-free survival with adjuvant therapy.

While the overall benefit of chemotherapy or immunotherapy appears to be minimal, there seems to be a select group of patients who will benefit of these approaches. Cisplatin-Gemcitabine has significant activity with a favorable toxicity profile in urothelial cancers and has caused some significant response in patients with CDC. Thus access to the system to some extent, since the preferred first-line chemotherapy simply because it is less toxic than MVAC regimen, and no other major series of chemotherapy for collecting duct tumors has apparently better results.

Papillary adenoma Tumors of the Kidney

Historically, the adenomas were recognized as lesions less than 3 cm based on the work of Bell. This was later modified identified in 1970 by Murphy and Mostofi who felt that the histological differentiation of Aden carcinomas adenomas was true possible. Renal papillary adenomas are small, discrete, and arise from renal tubular epithelium. In autopsy studies, increasing in frequency with age (7-40%).

Pathology
In the most recent WHO classification, papillary adenomas are less than 5 mm in diameter with a low nuclear grade. They appear as pale yellow, gray, well circumscribed nodules, usually below the renal capsule in the renal cortex. They usually not encapsulated, however, some have thin pseudo capsule. In microscopic examination, which have tubular architecture, papillary or tubular-like papillary renal cell carcinoma. The cells have scant cytoplasm, round to oval nuclei and have high nuclear grade (Fuhrman nuclear grade 3 or 4). Cytogenetics Features include trisomy (chromosome 7 and 17) and the loss of similarity chromosome. The And in this tumor with papillary renal cell carcinoma has led to the view that it may represent a precursor lesion for CRC.

Clinical presentation and treatment
Most of these lesions are discovered accidentally. They tend to occur more frequently in patients with underlying kidney disease related to atherosclerosis, scarring, acquired renal cystic disease secondary to hemodialysis, and other malignancy prevailing conditions of the kidney.

With small tumors incidentally detected increasingly during radiological procedures, the current view is to consider them all as probable early cancer to a clear marker of benignity is discovered. Renal tumors with diameters of 0.5 to 2 cm often behave sluggish, although the biologic behavior is difficult to determine, so that tumors less than 2 cm

They are sometimes called "renal epithelial tumors of uncertain malignant potential, and observed for progression, while Larger tumors may require surgical removal, depending on the clinical scenario. There is no defined role for radiation therapy or chemotherapy in the treatment of renal papillomas.