Magnetic Resonance Imaging (MRI) scans provide an image of the soft tissues in the body using radio waves and strong magnets. MRI can be used instead of CT if the patient exhibits an allergy to the contrast media administered for the test. Sometimes prior to the MRI scan, an intravenous injection of a contrasting material called gadolinium is given to allow for a more detailed image. Patients on dialysis or those who have renal insufficiency should avoid this contrasting material as it may induce a rare, yet severe, side effect known as nephrogenic systemic fibrosis. A bone scan or brain imaging is not routinely performed unless signs or symptoms suggest potential metastatic involvement of these areas.

MRI scans should also be considered to evaluate tumour extension which has grown in major blood vessels, including the vena cava, in the abdomen. MRI can be used to observe the possible spread of cancer to the brain or spinal cord should the patient present symptoms that suggest this might be the case.

The first steps taken to diagnose this condition are consideration of the signs and symptoms, and a medical history (the detailed medical review of past health state) to evaluate any risk factors. Based on the symptoms presented, a range of biochemical tests (using blood and/or urine samples) may also be considered as part of the screening process to provide sufficient quantitative analysis of any differences in electrolytes, renal and liver function, and blood clotting times. Upon physical examination, palpation of the abdomen may reveal the presence of a mass or an organ enlargement.

Although this disease lacks characterization in the early stages of tumor development, considerations based on diverse clinical manifestations, as well as resistance to radiation and chemotherapy are important. The main diagnostic tools for detecting renal cell carcinoma are ultrasound, computed tomography (CT) scanning and magnetic resonance imaging (MRI) of the kidneys.

As metanephric adenomas are considered benign, they can be left in place, i.e. no treatment is needed.

Metanephric adenoma is diagnosed histologically. The tumours can be located at upper pole, lower pole and mid-hilar region of the kidney; they are well circumscribed but unencapsulated, tan pink, with possible cystic and hemorrhagic foci. They show a uniform architecture of closely packed acinar or tubular structures of mature and bland appearance with scanty interposed stroma. Cells are small with dark staining nuclei and inconspicuous nucleoli. Blastema is absent whereas calcospherites may be present. Glomeruloid figures are a striking finding, reminiscent of early fetal metenephric tissue. The lumen of the acini may contain otherwise epithelial infoldings or fibrillary material but it is quite often empty. Mitoses are conspicuously absent.

In the series reported by Jones "et al." tumour cells were reactive for Leu7 in 3 cases of 5, to vimentine in 4 of 6, to cytocheratin in 2 of 6, to epithelial membrane antigen in 1 of 6 cases and muscle specific antigen in 1 of 6.

Olgac "et al." found that intense and diffuse immunoreactivity for alpha-methylacyl-CoA racemase (AMACR) is useful in differentiating renal cell carcinoma from MA but a panel including AMACR, CK7 and CD57 is better in this differential diagnosis.

Differential diagnosis may be quite difficult indeed as exemplified by the three malignancies initially diagnosed as MA that later metastasized, in the report by Pins et al.

Differential diagnosis of this condition includes the Birt-Hogg-Dubé syndrome and tuberous sclerosis. As the skin lesions are typically painful, it is also often necessary to exclude other painful tumors of the skin (including blue rubber bleb nevus, leiomyoma, eccrine spiradenoma, neuroma, dermatofibroma, angiolipoma, neurilemmoma, endometrioma, glomus tumor and granular cell tumor; the mnemonic "BLEND-AN-EGG" may be helpful). Other skin lesions that may need to be considered include cylindroma, lipoma, poroma and trichoepithelioma; these tend to be painless and have other useful distinguishing features.

PUNLMPs are exophytic lesions that appear friable to the naked eye and when imaged during cystoscopy.

They are definitively diagnosed after removal by microscopic examination by pathologists.

Histologically, they have a papillary architecture with slender fibrovascular cores and rare basal mitoses. The papillae rarely fuse and uncommonly branch. Cytologically, they have uniform nuclear enlargement.

They cannot be reliably differentiated from low grade papillary urothelial carcinomas using cytology, and their diagnosis (vis-a-vis low grade papillary urothelial carcinoma) has a poor inter-rater reliability.

Pathologic grading and staging tumors are:

graded by the degree of cellular atypia (G1->G3), and

staged:

Intraductal papillary mucinous neoplasms can come to clinical attention in a variety of different ways. The most common symptoms include abdominal pain, nausea and vomiting. The most common signs patients have when they come to medical attention include jaundice (a yellowing of the skin and eyes caused by obstruction of the bile duct), weight loss, and acute pancreatitis. These signs and symptoms are not specific for an intraductal papillary mucinous neoplasm, making it more difficult to establish a diagnosis. Doctors will therefore often order additional tests.

Once a doctor has reason to believe that a patient may have an intraductal papillary mucinous neoplasm, he or she can confirm that suspicion using one of a number of imaging techniques. These include computerized tomography (CT), endoscopic ultrasound (EUS), and magnetic resonance cholangiopancreatography (MRCP). These tests will reveal dilatation of the pancreatic duct or one of the branches of the pancreatic duct. In some cases a fine needle aspiration (FNA) biopsy can be obtained to confirm the diagnosis. Fine needle aspiration biopsy can be performed through an endoscope at the time of endoscopic ultrasound, or it can be performed through the skin using a needle guided by ultrasound or CT scanning.

IPMN forms cysts (small cavities or spaces) in the pancreas. These cysts are visible in CT scans (X-ray computed tomography). However, many pancreatic cysts are benign (see Pancreatic disease).

A growing number of patients are now being diagnosed before they develop symptoms (asymptomatic patients). In these cases, the lesion in the pancreas is discovered accidentally (by chance) when the patient is being scanned (i.e. undergoing an ultrasound, CT or MRI scan) for another reason. Up to 6% of patients undergoing pancreatic resection did so for treatment of incidental IPMNs.

In 2011, scientists at Johns Hopkins reported that they have developed a gene-based test that can be used to distinguish harmless from precancerous pancreatic cysts. The test may eventually help patients with harmless cysts avoid needless surgery. Bert Vogelstein and his colleagues discovered that almost all of the precancerous cysts (intraductal papillary mucinous neoplasms) of the pancreas have mutations in the KRAS and/or the GNAS gene. The researchers then tested a total of 132 intraductal papillary mucinous neoplasms for mutations in KRAS and GNAS. Nearly all (127) had mutations in GNAS, KRAS or both. Next, the investigators tested harmless cysts such as serous cystadenomas, and the harmless cysts did not have GNAS or KRAS mutations. Larger numbers of patients must be studied before the gene-based test can be widely offered.

The skin lesions may be difficult to diagnose clinically but a punch biopsy will usually reveal a Grenz zone separating the tumour from the overlying skin. Histological examination shows dense dermal nodules composed of elongated cells with abundant eosinophilic cytoplasm arranged in fascicles (spindle cells). The nuclei are uniform, blunt-ended and cigar-shaped with only occasional mitoses. Special stains that may be of use in the diagnosis include Masson's trichrome, Van Gieson's stain and phosphotungstic acid–haematoxylin.

The renal cell carcinomas have prominent eosinophilic nucleoli surrounded by a clear halo.

Birt–Hogg–Dubé can be difficult to diagnose from symptoms alone, because hereditary renal cancers, pneumothorax, and cutaneous tumors occur with other syndromes. Hereditary bilateral, multifocal kidney tumors similar to those seen in BHDcan occur with von Hippel–Lindau disease (clear cell renal cell carcinoma), hereditary papillary renal cancer (papillary renal cell carcinoma), and hereditary leiomyomatosis and renal cell cancer syndrome. They are differentiated with examination of the tumors' histology.

Hereditary recurrent pneumothorax or pulmonary cysts are associated with Marfan syndrome, Ehlers–Danlos syndrome, Tuberous Sclerosis Complex (TSC), alpha1-antitrypsin deficiency, and cystic fibrosis. Non-hereditary recurrent pneumothorax and/or pulmonary cysts can occur with Langerhans cell histiocytosis and lymphangioleiomyomatosis. These conditions are differentiated from Birt–Hogg–Dubé through examining the patient history and performing a physical examination. In women suspected to have the disease, ruling out pulmonary or thoracic endometriosis may be necessary.

Though fibrofolliculomas are unique to Birt–Hogg–Dubé, they may present with an ambiguous appearance and must be confirmed histologically. Other diseases can mimic the dermatologic manifestations of BHD, including tuberous sclerosis complex, Cowden syndrome, familial trichoepitheliomas, and multiple endocrine neoplasia type 1. Tuberous sclerosis must be distinguished because both disorders can present with angiofibromas on the face, though they are more common in tuberous sclerosis.

The cutaneous manifestations of Birt–Hogg–Dubé were originally described as fibrofolliculomas (abnormal growths of a hair follicle), trichodiscomas (hamartomatous lesions with a hair follicle at the periphery, often found on the face), and acrochordons (skin tags). Cutaneous manifestations are confirmed by histology. Most individuals (89%) with BHD are found to have multiple cysts in both lungs, and 24% have had one or more episodes of pneumothorax. The cysts can be detected by chest CT scan. Renal tumors can manifest as multiple types of renal cell carcinoma, but certain pathological subtypes (including chromophobe, oncocytoma, and oncocytic hybrid tumors) are more commonly seen. Although the original syndrome was discovered on the basis of cutaneous findings, it is now recognized that individuals with Birt–Hogg–Dubé may only manifest the pulmonary and/or renal findings, without any skin lesions. Though these signs indicate BHD, it is only confirmed with a genetic test for FLCN mutations.

Serous cystic neoplasms can come to clinical attention in a variety of ways. The most common symptoms are very non-specific and include abdominal pain, nausea and vomiting. In contrast to many of the other tumors of the pancreas, patients rarely develop jaundice (a yellowing of the skin and eyes caused by obstruction of the bile duct), or weight loss. These signs and symptoms are not specific for a serous cystic neoplasm, making it more difficult to establish a diagnosis. Doctors will therefore often order additional tests.

Once a doctor has reason to believe that a patient may have serous cystic neoplasm, he or she can confirm that suspicion using one of a number of imaging techniques. These include computerized tomography (CT), endoscopic ultrasound (EUS), and magnetic resonance cholangiopancreatography (MRCP). These tests will reveal a cystic mass within the pancreas. The cysts do not communicate with the larger pancreatic ducts. In some cases a fine needle aspiration (FNA) biopsy can be obtained to confirm the diagnosis. Fine needle aspiration biopsy can be performed through an endoscope at the time of endoscopic ultrasound, or it can be performed through the skin using a needle guided by ultrasound or CT scanning.

A growing number of patients are now being diagnosed before they develop symptoms (asymptomatic patients). In these cases, the lesion in the pancreas is discovered accidentally (by chance) when the patient is being scanned (x-rayed) for another reason.

While the histopathologic features and molecular features of ADH are that of (low-grade) DCIS, its clinical behaviour, unlike low-grade DCIS, is substantially better; thus, the more aggressive treatment for DCIS is not justified. In oncology in general, it is observed that tumour size is often strongly predictive of the clinical behaviour and, thus, a number of cancers (e.g. adenocarcinoma of the lung, papillary renal cell carcinoma) are defined, in part, on the basis of a minimum size.

ADH, if found on a surgical (excisional) biopsy of a mammographic abnormality, does not require any further treatment, only mammographic follow-up.

If ADH is found on a core (needle) biopsy (a procedure which generally does not excise a suspicious mammographic abnormality), a surgical biopsy, i.e. a breast lumpectomy, to completely excise the abnormality and exclude breast cancer is the typical recommendation.

PUNLMPs are treated like non-invasive low grade papillary urothelial carcinomas, excision and regular follow-up cystoscopies.

There is a rare occurrence of a pelvic recurrence of a low-grade superficial TCC after cystectomy. Delayed presentation with recurrent low-grade urothelial carcinoma is an unusual entity and potential mechanism of traumatic implantation should be considered. Characteristically low-grade tumors are resistant to systemic chemotherapy and curative-intent surgical resection of the tumor should be considered.

The 1973 WHO grading system for TCCs (papilloma, G1, G2 or G3) is most commonly used despite being superseded by the 2004 WHO grading (papillary neoplasm of low malignant potential [PNLMP], low grade, and high grade papillary carcinoma).

MTSCC can be a difficult diagnosis due to its morphologic heterogeneity. Several morphological variants have been described, as the ‘‘mucin-poor variants’’, showing a predominance of tubular or spindle cell components and only minimal pale mucinous background.

Focal papillations or papillary cores and foamy histiocytes can also be seen, creating confusion with type 1 papillary RCC. Helpful features for diagnosis are bland cytologic features and adjacent tubular and spindle cell components. Focal areas of clear cells and oncocytic cells can also be present.

Prognosis is highly variable and dependent upon a multitude of factors. Reoccurrence does occur. Treatment is determined on a case-by-case basis.

The clinical and pathology differential are different. From a pathology perspective, an endolymphatic sac tumor needs to be separated from metastatic renal cell carcinoma, metastatic thyroid papillary carcinoma, middle ear adenoma, paraganglioma, choroid plexus papilloma, middle ear adenocarcinoma, and ceruminous adenoma.

Individuals with renal papillary necrosis due to excess use of analgesic have an elevated risk of epithelial tumors, hence a urine cytology exam is useful. In terms of imaging this condition can be identified by retrograde pyelography (RGP). The diagnosis of renal papillary necrosis is therefore done via:

Diagnosis may include a fluorescence in situ hybridization (FISH) test, computed tomography urography (CTU), magnetic resonance urography (MRU), intravenous pyelography (IVP) x-ray, ureteroscopy, or biopsy.

The United States' NIH estimates for 2013 around 64,770 new cases of kidney cancer and 13,570 deaths from the disease.

The incidence of kidney cancer is also increasing in the United States. This is thought to be a real increase, not only due to changes in the way the disease is diagnosed.

Wide excision is the treatment of choice, although attempting to preserve hearing. Based on the anatomic site, it is difficult to completely remove, and so while there is a good prognosis, recurrences or persistence may be seen. There is no metastatic potential. Patients who succumb to the disease, usually do so because of other tumors within the von Hippel-Lindau complex rather than from this tumor.

MTSCC is of low-grade malignancy. Some rare cases of lymph node metastasis and recurrence have been described. Two cases of MTSCC with sarcomatoid change have been described, one with widespread metastasis to distant organs, including lung and bone.

A spindled component is characteristic of MTSCC, but the presence of significant pleomorphism with prominent nucleoli and mitotic activity, and necrosis should raise concern for a sarcomatoid change. Microscopic necrosis can be seen focally in MTSCC. Its significance is unknown. The presence of any necrosis should be mentioned in the pathological report.

The most recent estimates of incidence of kidney cancer suggest that there are 63,300 new cases annually in the EU25. In Europe, kidney cancer accounts for nearly 3% of all cancer cases.

They are benign lesions and malignant degeneration is rare. They are usually treated with curettage which however have a high recurrence rate of 25%. As such if an en-bloc resection is possible this is advisable