StemCell Therapy

More than 55% of VHL-affected individuals develop only multiple renal cell cysts. The VHL-associated RCCs that occur are characteristically multifocal and bilateral and present as a combined cystic and solid mass.[66] Among individuals with VHL, the cumulative RCC risk has been reported as 24% to 45% overall. RCCs smaller than 3 cm in this disease tend to be low grade (Fuhrman nuclear grade 2) and minimally invasive,[67] and their rate of growth varies widely.[68] An investigation of 228 renal lesions in 28 patients who were followed up for at least 1 year showed that transition from a simple cyst to a solid lesion was infrequent.[66] Complex cystic and solid lesions contained neoplastic tissue that uniformly enlarged. These data may be used to help predict the progression of renal lesions in VHL. Figure 1 depicts bilateral renal tumors in a patient with VHL.

EnlargeFigure 1. von Hippel-Lindau diseaseassociated renal cell cancers are characteristically multifocal and bilateral and present as a combined cystic and solid mass. Red arrow indicates a lesion with a solid and cystic component, and white arrow indicates a predominantly solid lesion.

Tumors larger than 3 cm may increase in grade as they grow, and metastasis may occur.[68,69] RCCs often remain asymptomatic for long intervals.

Patients can also develop pancreatic cysts, cystadenomas, and pancreatic NETs.[2] Pancreatic cysts and cystadenomas are not malignant, but pancreatic NETs possess malignant characteristics and are typically resected if they are 3 cm or larger (2 cm if located in the head of the pancreas).[70] A review of the natural history of pancreatic NETs shows that these tumors may demonstrate nonlinear growth characteristics.[71]

Retinal manifestations, first reported more than a century ago, were one of the first recognized aspects of VHL. Retinal hemangioblastomas (also known as capillary retinal angiomas) are one of the most frequent manifestations of VHL and are present in more than 50% of patients.[72] Retinal involvement is one of the earliest manifestations of VHL, with a mean age at onset of 25 years.[1,2] These tumors are the first manifestation of VHL in nearly 80% of affected individuals and may occur in children as young as 1 year.[2,73,74]

Retinal hemangioblastomas occur most frequently in the periphery of the retina but can occur in other locations such as the optic nerve, a location much more difficult to treat. Retinal hemangioblastomas appear as a bright orange spherical tumor supplied by a tortuous vascular supply. Nearly 50% of patients have bilateral retinal hemangioblastomas.[72] The median number of lesions per affected eye is approximately six.[75] Other retinal lesions in VHL can include retinal vascular hamartomas, flat vascular tumors located in the superficial aspect of the retina.[76]

Longitudinal studies are important for the understanding of the natural history of these tumors. Left untreated, retinal hemangioblastomas can be a major source of morbidity in VHL, with approximately 8% of patients [72] having blindness caused by various mechanisms, including secondary maculopathy, contributing to retinal detachment, or possibly directly causing retinal neurodegeneration.[77] Patients with symptomatic lesions generally have larger and more numerous retinal hemangioblastomas. Long-term follow-up studies demonstrate that most lesions grow slowly and that new lesions do not develop frequently.[75,78]

Hemangioblastomas are the most common disease manifestation in patients with VHL, affecting more than 70% of individuals. A prospective study assessed the natural history of hemangioblastomas.[79] The mean age at onset of CNS hemangioblastomas is 29.1 years (range, 773 y).[80] After a mean follow-up of 7 years, 72% of the 225 patients studied developed new lesions.[81] Fifty-one percent of existing hemangioblastomas remained stable. The remaining lesions exhibited heterogeneous growth rates, with cerebellar and brainstem lesions growing faster than those in the spinal cord or cauda equina. Approximately 12% of hemangioblastomas developed either peritumoral or intratumoral cysts, and 6.4% were symptomatic and required treatment. Increased tumor burden or total tumor number detected was associated with male sex, longer follow-up, and genotype (all P < .01). Partial germline deletions were associated with more tumors per patient than were missense variants (P < .01). Younger patients developed more tumors per year. Hemangioblastoma growth rate was higher in men than in women (P < .01). Figures 2 and 3 depict cerebellar and spinal hemangioblastomas, respectively, in patients with VHL.

EnlargeFigure 2. Hemangioblastomas are the most common disease manifestation in patients with von Hippel-Lindau disease. The left panel shows a sagittal view of brainstem and cerebellar lesions. The middle panel shows an axial view of a brainstem lesion. The right panel shows a cerebellar lesion (red arrow) with a dominant cystic component (white arrow).

EnlargeFigure 3. Hemangioblastomas are the most common disease manifestation in patients with von Hippel-Lindau disease. Multiple spinal cord hemangioblastomas are shown.

The rate of pheochromocytoma formation in the VHL patient population is 25% to 30%.[82,83] Of patients with VHL-associated pheochromocytomas, 44% developed disease in both adrenal glands.[84] The rate of malignant transformation is very low. Levels of plasma and urine normetanephrine are typically elevated in patients with VHL,[85] and approximately two-thirds will experience physical manifestations such as hypertension, tachycardia, and palpitations.[82] Patients with a partial loss of VHL function (Type 2 disease) are at higher risk of pheochromocytoma than are VHL patients with a complete loss of VHL function (Type 1 disease); the latter develop pheochromocytoma very rarely.[13,14,82,86] The rate of VHL germline pathogenic variants in nonsyndromic pheochromocytomas and paragangliomas was very low in a cohort of 182 patients, with only 1 of 182 patients ultimately diagnosed with VHL.[87]

Paragangliomas are rare in VHL patients but can occur in the head and neck or abdomen.[88] A review of VHL patients who developed pheochromocytomas and/or paragangliomas revealed that 90% of patients manifested pheochromocytomas and 19% presented with a paraganglioma.[84]

The mean age at diagnosis of VHL-related pheochromocytomas and paragangliomas is approximately 30 years,[83,89] and patients with multiple tumors were diagnosed more than a decade earlier than patients with solitary lesions in one series (19 vs. 34 y; P < .001).[89] Diagnosis of pheochromocytoma was made in patients as young as 5 years in one cohort,[83] providing a rationale for early testing. All 21 pediatric patients with pheochromocytomas in this 273-patient cohort had elevated plasma normetanephrines.[83]

VHL patients may develop multiple serous cystadenomas, pancreatic NETs, and simple pancreatic cysts.[1] VHL patients do not have an increased risk of pancreatic adenocarcinoma. Serous cystadenomas are benign tumors and warrant no intervention. Simple pancreatic cysts can be numerous and rarely cause symptomatic biliary duct obstruction. Endocrine function is nearly always maintained; occasionally, however, patients with extensive cystic disease requiring pancreatic surgery may ultimately require pancreatic exocrine supplementation.

Pancreatic NETs are usually nonfunctional but can metastasize (to lymph nodes and the liver). The risk of pancreatic NET metastasis was analyzed in a large cohort of patients, in which the mean age at diagnosis of a pancreatic NET was 38 years (range, 1668 y).[90] The risk of metastasis was lower in patients with small primary lesions (3 cm), in patients without an exon 3 pathogenic variant, and in patients whose tumor had a slow doubling time (>500 days). Nonfunctional pancreatic NETs can be followed by imaging surveillance with intervention when tumors reach 3 cm. Lesions in the head of the pancreas can be considered for surgery at a smaller size to limit operative complexity.

ELSTs are adenomatous tumors arising from the endolymphatic duct or sac within the posterior part of the petrous bone.[91] ELSTs are rare in the sporadic setting, but are apparent on imaging in 11% to 16% of patients with VHL. Although these tumors do not metastasize, they are locally invasive, eroding through the petrous bone and the inner ear structures.[91,92] Approximately 30% of VHL patients with ELSTs have bilateral lesions.[91,93]

ELSTs are an important cause of morbidity in VHL patients. ELSTs evident on imaging are associated with a variety of symptoms, including hearing loss (95% of patients), tinnitus (92%), vestibular symptoms (such as vertigo or disequilibrium) (62%), aural fullness (29%), and facial paresis (8%).[91,92] In approximately half of patients, symptoms (particularly hearing loss) can occur suddenly, probably as a result of acute intralabyrinthine hemorrhage.[92] Hearing loss or vestibular dysfunction in VHL patients can also present in the absence of radiologically evident ELSTs (approximately 60% of all symptomatic patients) and is believed to be a consequence of microscopic ELSTs.[91]

Hearing loss related to ELSTs is typically irreversible; serial imaging to enable early detection of ELSTs in asymptomatic patients and resection of radiologically evident lesions are important components in the management of VHL patients.[94,95] Surgical resection by retrolabyrinthine posterior petrosectomy is usually curative and can prevent onset or worsening of hearing loss and improve vestibular symptoms.[92,94]

Tumors of the broad ligament can occur in females with VHL and are known as papillary cystadenomas. These tumors are extremely rare, and fewer than 20 have been reported in the literature.[96] Papillary cystadenomas are histologically identical to epididymal cystadenomas commonly observed in males with VHL.[97] One important difference is that papillary cystadenomas are almost exclusively observed in patients with VHL, whereas epididymal cystadenomas in men can occur sporadically.[98] These tumors are frequently cystic, and although they become large, they generally have a fairly indolent behavior.

Fluid-filled epididymal cysts, or spermatoceles, are very common in adult men. In VHL, the epididymis can contain more complex cystic neoplasms known as papillary cystadenomas, which are rare in the general population. More than one-third of all cases of epididymal cystadenomas reported in the literature and most cases of bilateral cystadenomas have been reported in patients with VHL.[99] These well-circumscribed lesions have variable amounts of cystic and papillary components that are lined with epithelial cuboidal or columnar clear cells.[100] Among symptomatic patients, the most common presentation of epididymal cystadenoma is a painless, slow-growing scrotal swelling. The differential diagnoses of epididymal tumors include adenomatoid tumor (which is the most common tumor in this site), metastatic ccRCC, and papillary mesothelioma.[101]

In a small series, histological analysis did not reveal features typically associated with malignancy, such as mitotic figures, nuclear pleomorphism, and necrosis. Lesions were strongly positive for CK7 and negative for RCC. Carbonic anhydrase IX (CAIX) was positive in all tumors. PAX8 was positive in most cases. These features were reminiscent of clear cell papillary RCC, a relatively benign form of RCC without known metastatic potential.[97]

See the article here:
Genetics of Kidney Cancer (Renal Cell Cancer) (PDQ ...

This entry was posted on October 2, 2019 at 2:47 am and is filed under Stem Cell kidney Failure. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed. |