Low-grade clear cell renal cell carcinoma mimicking hemangioma of the kidney: a series of 4 cases

Clinicopathological and molecular features of renal cell carcinomas with haemangioblastoma-like features distinct from clear cell renal cell carcinoma

AIMS

Haemangioblastomas arise in the central nervous system. Rarely, haemangioblastomas may develop in extra-neural sites, such as the kidneys. A few reported cases of renal cell carcinomas (RCCs) with haemangioblastoma-like features have exhibited both clear cell renal cell carcinoma (CCRCC)- and haemangioblastoma-like components. The clinicopathological and molecular characteristics of RCCs with haemangioblastoma-like features were analysed, focusing on VHL alterations, in comparison with CCRCCs partially resembling haemangioblastoma.

METHODS AND RESULTS

Four RCCs with haemangioblastoma-like features and five CCRCCs partially resembling haemangioblastoma were included. The RCCs with haemangioblastoma-like features were indolent and lacked adverse prognostic factors. All RCCs with haemangioblastoma-like features had a well-circumscribed appearance and a thick fibromuscular capsule, with fibromuscular bundles extending into the tumour to varying degrees in the three tumours. Each RCC with haemangioblastoma-like features exhibited CCRCC-like areas with indistinct tubular structures and foci of haemangioblastoma-like areas, in which vessels and short spindle cells overwhelmed tumour cells. Whereas haemangioblastoma-like areas in the CCRCCs partially resembling haemangioblastoma exhibited sparse vessels and spindle cells and distinct clear cells. The RCCs with haemangioblastoma-like features exhibited a unique immunohistochemical profile, with positive staining for inhibin-α, S100, carbonic-anhydrase-9, keratin7, and high molecular weight keratin and negative staining for (alpha-methylacyl-CoA racemase) AMACR. RCC with haemangioblastoma-like features did not display any VHL alterations, including VHL mutation, 3p LOH, and methylation of the VHL promoter region, and the two tumours harboured a likely oncogenic missense variant of MTOR (c.7280T>G).

CONCLUSION

The histopathological, immunohistochemical, and molecular findings suggest that RCC with haemangioblastoma-like features is a distinct entity from CCRCC.

Current Knowledge and Prospects for Renal Hemangioblastoma and Renal Cell Carcinoma with Hemangioblastoma-like Features

Tumors exhibiting histopathological findings similar to those of hemangioblastoma of the central nervous system (CNS-HB) rarely develop in the kidneys. Currently, renal hemangioblastoma (RHB) is considered analogous to CNS-HB; however, they differ in gross appearance, as well as immunohistochemical and molecular findings. In contrast, some renal cell carcinomas reportedly comprise distinct, clear cell renal cell carcinoma (CCRCC)- and hemangioblastoma (HB)-like areas. Initially, renal cell carcinomas with HB-like features (RCC-HBs) were considered a morphological variant of CCRCC owing to their diverse histological findings. However, the immunohistochemical and molecular findings of RCC-HBs suggest that RCC-HB is distinct from CCRCC. Additionally, one of the RCC-HBs had a focal leiomyomatous stroma and TSC2 variant, suggesting that RCC-HB and RCC with fibromyomatous stroma (RCC-FMS) might belong to the same disease entity. Therefore, we comprehensively reviewed the clinical, pathological, and molecular features of RHB, RCC-HB, and the related tumors and discussed the similarities, differences, and relationships between them. We believe that our review would serve as a foundation for further investigation on elucidating the relationship between CNS-HB, RHB, RCC-HB, and RCC-FMS.

Metastatic Clear Cell Renal Cell Carcinoma Involving the Thyroid Gland: A Clinicopathologic Study of 17 Patients

Background. Metastatic clear cell renal cell carcinoma (RCC) is one of the most common secondary thyroid malignancies. Diagnosis can be challenging, particularly if presenting many years after initial diagnosis. We reviewed clinicopathologic features and immunoprofile of metastatic clear cell RCC in thyroid. Design. We identified 17 patients from 2003-2021. Clinical data were obtained from medical records, and slides were retrieved and reviewed. Results. Seventeen patients (12 male and 5 female) included 12 thyroidectomies, 3 core biopsies, 1 excisional biopsy, and 1 fine-needle aspiration. The average patient age was 68.7 years (range, 45-88 years). Sixteen patients had history of clear cell RCC, and in 1 patient, the clear cell RCC was discovered after the thyroid metastasis was found. Thyroid gland metastases were on average diagnosed 90.7 months after the diagnosis of the renal primary (range, 24-240 months). Patients presented with a new palpable mass (n = 11) or dyspnea/stridor (n = 1). Five tumors were incidentally found via surveillance imaging. In 2 patients, metastases occurred within follicular thyroid neoplasms. All metastases showed conspicuous sinusoidal vasculature between the tumor nests and areas of myxoid degeneration. A prominent thick fibromuscular pseudocapsule was evident in 10 resections. Immunohistochemistry (n = 5) showed that the metastases were positive for PAX8, CA9, and CD10, while negative for keratin 7, thyroglobulin, and TTF1. Conclusions. Metastatic clear cell RCC involving the thyroid gland is infrequent and typically occurs remotely after the initial diagnosis. Cytologic and histologic features may show significant overlap with primary thyroid lesions. Immunohistochemistry can help reliably distinguish metastases from primary thyroid neoplasms.

A rare pericytic tumor of the kidney: The first case in Korea

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The family of pericytic tumors includes glomus tumors and variants, myopericytoma including myofibroma, and angioleiomyoma.

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The renal pericytic tumor is extremely rare, and only few comprehensive discussions about this entity have been done.

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We report the first documented case of renal pericytic tumor in a 58-year-old Korean male.

Introduction

A pericytic tumor is a group of mesenchymal neoplasm found in superficial tissues and only rarely described in viscera. The family of pericytic tumors includes glomus tumors and variants, myopericytoma including myofibroma, and angioleiomyoma etc. The renal pericytic tumor is extremely rare, and only few comprehensive discussions about this entity have been done.

Presentation of case

A 58-year-old man was transferred to our institute with suspicions of renal cell carcinoma. The kidney dynamic computed tomography scan showed a 3 cm sized solid mass in the upper pole of the right kidney. Laparoscopic radical nephrectomy was performed due to the deep-seated mass. Pathological result confirmed that the kidney mass was renal pericytic tumor.

Discussion

Although general biological behavior of published renal pericytic tumors is likely to be benign, the clinicopathologic experiences are very limited. Therefore, we should evaluate the malignant potential of the entity according to the parameters proposed for soft tissue tumors, including tumor location, tumor size, growth pattern, cellularity, cytological atypia, and mitotic figures with atypical forms. The current case shows several worrisome features, including an extremely rare tumor location, partially infiltrative growth, and a mildly increased proliferating index, which resulted in it being classified as an uncertain malignant potential.

Conclusion

We described the first case of renal pericytic tumor, addressing uncertain malignant potential, in a Korean male, which would be a distinct mesenchymal neoplasm differentiating from other groups of perivascular tumor families based on histological and immunohistochemical features.

Pediatric Anastomosing Hemangioma: Case Report and Review of Renal Vascular Tumors in Children

The case involves a 10-year-old child who underwent a left radical nephrectomy for what was believed to be a Wilms' tumor. Histopath examination indicated a benign vascular lesion, subsequently determined to be an anastomosing hemangioma of the kidney. A comparison with the previously cited pediatric patients with renal vascular tumors is provided, and the inconsistent diagnostic terminologies for these conditions are highlighted. The therapeutic implications of these predominantly benign renal tumors, in the context of the much more frequently encountered malignant neoplasms in children, are additionally discussed.

Renal Cell Carcinoma With Hemangioma-Like Features: Diagnostic Implications and Review of the Literature

Renal cell carcinoma (RCC) with clear cell morphology may show a prominent delicate vascularity. In this article, we report the morphologic and immunohistochemical features of a clear cell papillary RCC mimicking hemangioblastoma and a clear cell RCC mimicking hemangioma. Case 1 showed tubular and papillary growth of clear cells with distinctive areas of capillary proliferation and admixed stromal-like cells resembling a hemangioblastoma. Case 2 consisted of homogeneously delicate microvascular proliferations resembling a capillary hemangioma with scattered inconspicuous clear cells. The clear cells of Case 1 were PAX8(+), CK7(diffuse+), CA9(diffuse+, cup-shaped), and inhibin A(−). The hemangioblastoma-like areas were PAX8(+), CK7(−), CA9(diffuse+), and inhibin A(diffuse+). Case 2 showed PAX8(+), CK7(−), and CA9(diffuse+). They can be diagnostically challenging, and it is important to recognize that a pure hemangioma or hemangioblastoma of the kidneys is very rare, and that RCCs with clear cell morphology rarely exhibit hemangioma-like characteristics.

Unclassified renal cell carcinoma: diagnostic difficulties and treatment modalities

Over the past few decades, the classification system of renal cell carcinoma (RCC) variants has witnessed tremendous and ongoing refinement driven by genomic profiling and morphological correlation that have provided valuable insights into tumor biology and characterization of this heterogeneous subset of tumors. The importance of accurate classification cannot be understated given the downstream impact on treatment decisions, risk stratification, and need for genetic testing. While the morphologic heterogeneity across these tumors is increasingly being recognized, all non-clear-cell RCCs are commonly categorized under one therapeutic category with management strategies that largely derive from clear-cell RCCs. As research in metastatic RCC progresses, there is a growing focus on rare subtypes and unclassified tumors, which is rapidly changing the treatment paradigm for non-clear-cell RCC. This review focuses on the histomorphologic diagnostic challenges of unclassified RCCs discussing the utility of contemporary diagnostic tools. It further discusses the current state of knowledge and guidelines for management of this class of tumors.

Anastomosing hemangioma with extensive fatty stroma in the retroperitoneum

Anastomosing hemangiomas are a recently recognized benign vascular neoplasm, first described by Montgomery and Epstein in 2009. A few cases have been described in the genitourinary tract, especially in the renal hilum. These are fairly well-demarcated lesions with lobules of sinusoidal-like capillaries lined by hobnail endothelial cells containing eosinophilic hyaline globules in the cytoplasm. Extramedullary hematopoiesis has been described in a few cases, along with large feeding vessels. A predominant adipocytic component has been described in only one case.^[9] We describe a case of a retroperitoneal anastomosing hemangioma occurring in an extrarenal site in a 53-year-old female, followed by a review of the current literature.

Extraneuraxial Hemangioblastoma: Clinicopathologic Features and Review of the Literature

Extraneuraxial hemangioblastoma occurs in nervous paraneuraxial structures, somatic tissues, and visceral organs, as part of von Hippel-Lindau disease (VHLD) or in sporadic cases. The VHL gene plausibly plays a key role in the initiation and tumorigenesis of both central nervous system and extraneuraxial hemangioblastoma, therefore, the underlying molecular and genetic mechanisms of the tumor growth are initially reviewed. The clinical criteria for the diagnosis of VHLD are summarized, with emphasis on the distinction of sporadic hemangioblastoma from the form fruste of VHLD (eg, hemangioblastoma-only VHLD). The world literature on the topic of extraneuraxial hemangioblastomas has been comprehensively reviewed with ∼200 cases reported to date: up to 140 paraneuraxial, mostly of proximal spinal nerve roots, and 65 peripheral, 15 of soft tissue, 6 peripheral nerve, 5 bone, and 39 of internal viscera, including 26 renal and 13 nonrenal. A handful of possible yet uncertain cases from older literature are not included in this review. The clinicopathologic features of extraneuraxial hemangioblastoma are selectively presented by anatomic site of origin, and the differential diagnosis is emphasized in these subsets. Reference is made also to 10 of the authors' personal cases of extraneuraxial hemangioblastomas, which include 4 paraneuraxial and 6 peripheral (2 soft tissue hemangioblastoma and 4 renal).

Comparison of Renal Anastomosing Hemangiomas in End-Stage and Non–End-Stage Kidneys: A Meta-Analysis With a Report of 2 Cases

Background. Renal anastomosing hemangioma (RAH) is a very rare distinct entity composed of anastomosing sinusoidal (spleen-like) capillary-sized vessels lined by flat or hobnail endothelial cells. Most of the published cases of RAH occurred in the setting of end-stage renal disease (ESRD). Methods. We present 2 cases of RAH in ESRD along with a literature review. We compared clinicopathologic features of RAHs in end-stage and non–end-stage kidneys. A meta-analysis was conducted with PubMed and a manual search through references of relevant publications. Individual patient data gathered from the literature were used in the analysis. Results. Our systematic review revealed 49 RAHs, including our 2 cases. Thirty-two (65.3%) cases were in ESRD, only 17 (34.7%) were in patients with non-ESRD. RAHs in ESRD were in younger patients, smaller in size, multifocal, and seen more with renal epithelial neoplasms when compared with RAHs in non-ESRD ( P < .05). Extramedullary hematopoiesis was seen mostly in RAHs in ESRD kidneys (85% vs 41.7%) ( P = .018). Follow-up data were available for 25 cases with a mean follow-up of 24.58 ± 38.54 months. Recurrence, metastasis, or death have never been described related to RAH in any patients. Conclusions. In conclusion, RAHs are rare and mostly arise in kidneys with end-stage damage. RAHs in ESRD and non-ESRD differ in terms of clinicopathologic features.

Multilocular cystic renal cell carcinoma: pathological t staging makes no difference to favorable outcomes and should be reclassified. Bhatt JR, Jewett MA, Richard PO, Kawaguchi S, Timilshina N, Evans A, Alibhai S, Finelli A.J Urol. November 2016;196(5):1350-1355

OBJECTIVE

We evaluated survival outcomes of cystic/multilocular cystic renal cell carcinomas in a long-term population-based study based on size and pathological tumor stage.

MATERIALS AND METHODS

We, retrospectively, reviewed a provincial cancer registry of all histologically proven cases of multilocular cystic renal cancers treated surgically between 1995 and 2008. All cases of cystic necrosis were excluded from study. Primary end points were overall- and cancer-specific survival estimated using Kaplan-Meier curves. Cox proportional hazards models of univariable and multivariable analyses were used to assess for factors associated with survival.

RESULTS

Of 172 cases of cystic renal cancers 168 with complete data were analyzed, of which 98% were multilocular cystic. Median patient age at treatment was 55 years and 58% of the patients were male. More than 40% of cases were pT1b or greater, 15% were pT2 or greater and most cases were low Fuhrman grade (1-2). At a median follow-up of 9.75-years overall- and cancer-specific survival was 82.1% and 100%, respectively. No difference was noted in higher pathological T stage, size, or grade. Limitations inherent in population-based studies include under ascertainment of cause of death, lack of data on histologically benign cysts that are treated surgically and a lack of central pathology review.

CONCLUSIONS

Multilocular cystic renal cell carcinoma has an excellent prognosis, which remains unchanged regardless of tumor size or pathological T stage. This suggests a strong case for nephron and adrenal sparing surgery when indicated, and nonsurgical management when feasible. As postoperative follow-up protocols are dictated by staging, we propose that for this entity pathological T staging should be abandoned or reassigned as pT1c to guide clinicians.

Diagnostic Accuracy of Renal Mass Biopsy

We investigated the diagnostic accuracy of renal mass biopsy in an ex vivo model, as well as compared the agreement of the preoperative radiological diagnosis with the final pathologic diagnosis. Two 18-gauge needle-core and 2 vacuum-needle biopsies were performed ex vivo from the tumors of 100 consecutive patients undergoing radical nephrectomy between 2006 and 2010. The median tumor size was 5.5 cm. There was no significant difference with regard to cylinder length or tissue quality between the sampling methods. At least 1 of 4 needle cores contained diagnostic tissue in 88% of patients. Biopsy specimens identified clear cell (54%), papillary (13%), or chromophobe (5%) renal cell carcinoma; urothelial carcinoma (6%); oncocytoma (5%); liposarcoma (1%); metastatic colorectal carcinoma (1%); squamous cell carcinoma (1%); unclassified renal cell neoplasm (1%); and no tumor sampled (12%). The sensitivity of the biopsy for accurately determining the diagnosis was 88% (95% CI: 79% to 93%). The specificity was 100% (95% CI: 17% to 100%). Biopsy grade correlated strongly with final pathology (83.5% agreement). There was no difference in average tumor size in cases with the same versus higher grade on final pathology (5.87 vs 5.97; P = .87). Appraisal of tumor histology by radiology agreed with the pathologic diagnosis in 68% of cases. Provided that the biopsy samples the tumor tissue in a renal mass, pathologic analysis is of great diagnostic value in respect of grade and tumor type and correlates well with excisional pathology. This constitutes strong ground for increasingly used renal mass biopsy in patients considering active surveillance or ablation therapy.

Updates in Benign Lesions of the Genitourinary Tract

The genitourinary tract is a common site for new cancer diagnosis, particularly for men. Therefore, cancer-containing specimens are very common in surgical pathology practice. However, many benign neoplasms and nonneoplastic, reactive, and inflammatory processes in the genitourinary tract may mimic or cause differential diagnostic challenges with malignancies. Emerging clinicopathologic, immunohistochemical, and molecular characteristics have shed light on the pathogenesis and differential diagnosis of these lesions. This review addresses differential diagnostic challenges related to benign genitourinary tract lesions in the kidney, urinary bladder, prostate, and testis, with emphasis on recent advances in knowledge and areas most common in diagnostic practice.

Non-mesenchymal Mimics of Sarcoma

A variety of different non-mesenchymal neoplasms may mimic sarcoma, in particular sarcomatoid carcinoma and melanoma, but also mesothelioma and rarely some lymphomas. This article reviews the key clinical and histologic features of such neoplasms in different settings, along with the use of ancillary studies to help identify the tumor types most frequently misdiagnosed as sarcoma.

Characterization of Fibromuscular Pseudocapsule in Renal Cell Carcinoma

Pseudocapsule in renal cell carcinoma (RCC) has been described but little is known about its prevalence and extent. Pseudocapsule was analyzed in 105 RCCs (44 clear cell, 44 chromophobe, 17 papillary). Pseudocapsule was graded as follows: grade 1, thickness comparable to adjacent muscular arteries; grade 2, thickness more than twice the diameter of adjacent muscular arteries; grade 3, grade 2 findings with vasculopathy. Tumor size, tumor regression, and International Society of Urologic Pathology (ISUP) nucleolar grade were recorded. Cases with grade 3 pseudocapsule were stained with elastic silver stain, Alcian blue, smooth muscle actin, and CD31. More clear cell RCCs had pseudocapsule (89%, 39/44) than chromophobe (30%, 13/44) and papillary (35%, 6/17). Average tumor size with pseudocapsule was 3.9 cm; average tumor size without pseudocapsule was 3.8 cm (P = .77). Grade 2 pseudocapsule was common in clear cell RCC (56%, 22/39). Chromophobe and papillary RCC had grade 1 pseudocapsule in 77% (10/13) and 83% (5/6) of cases. Grade 3 pseudocapsule was only seen in clear cell RCC (10%, 4/39). No correlation was noted between degenerative tumor changes, tumor size, ISUP nucleolar grade, and presence and grade of pseudocapsule. Smooth muscle actin and CD31 showed abundant smooth muscle component and rich vasculature within the pseudocapsule. Arterial elastic membrane disruption and/or fibrointimal mucin deposits were present in grade 3 pseudocapsule. Thus, pseudocapsule is rather characteristic and more prominent in clear cell, less frequent in chromophobe, and rare in papillary RCC. Its presence may be evaluated radiologically or in biopsy specimens with scant tumor fragments.

Diagnostic approach to eosinophilic renal neoplasms

CONTEXT

Eosinophilic renal neoplasms include a spectrum of solid and papillary tumors ranging from indolent benign oncocytoma to highly aggressive malignancies. Recognition of the correct nature of the tumor, especially in biopsy specimens, is paramount for patient management.

OBJECTIVE

To review the diagnostic approach to eosinophilic renal neoplasms with light microscopy and ancillary techniques.

DATA SOURCES

Review of the published literature and personal experience.

CONCLUSIONS

The following tumors are in the differential diagnosis of oncocytic renal cell neoplasm: oncocytoma, chromophobe renal cell carcinoma (RCC), hybrid tumor, tubulocystic carcinoma, papillary RCC, clear cell RCC with predominant eosinophilic cell morphology, follicular thyroid-like RCC, hereditary leiomyomatosis-associated RCC, acquired cystic disease-associated RCC, rhabdoid RCC, microphthalmia transcription factor translocation RCC, epithelioid angiomyolipoma, and unclassified RCC. In low-grade nonpapillary eosinophilic neoplasms, distinction between oncocytoma and low-grade RCC mostly rests on histomorphology; however, cytokeratin 7 immunostain may be helpful. In high-grade nonpapillary lesions, there is more of a role for ancillary techniques, including immunohistochemistry for cytokeratin 7, CA9, CD10, racemase, HMB45, and Melan-A. In papillary eosinophilic neoplasms, it is important to distinguish sporadic type 2 papillary RCC from microphthalmia transcription factor translocation and hereditary leiomyomatosis-associated RCC. Histologic and cytologic features along with immunohistochemistry and fluorescence in situ hybridization tests for TFE3 (Xp11.2) and TFEB [t(6;11)] are reliable confirmatory tests. Eosinophilic epithelial neoplasms with architecture, cytology, and/or immunoprofile not qualifying for either of the established types of RCC should be classified as unclassified eosinophilic RCC and arbitrarily assigned a grade (low or high).

Haemangiomas in kidneys with end-stage renal disease: a novel clinicopathological association

AIMS

The study of haemangiomas in end-stage renal disease (ESRD).

METHODS AND RESULTS

Twenty ESRD nephrectomies from 16 patients (aged 9 months-68 years) were due to hypertension (four), focal segmental glomerulosclerosis (four), lupus nephritis (three), diabetes (one), IgA nephropathy (one), hereditary nephritis (one), congenital nephrotic syndrome (one) and unknown cause (one). Haemangiomas appeared as a single mass (15), two masses (one), three masses (one), four masses (two) and eight masses (one) per kidney. Tumours measured 0.2-3.5 cm. Four patients had bilateral haemangiomas. All tumours were in the medulla and often abutted renal sinus fat. All except one of the tumours were anastomosing haemangiomas, showing isolated or interconnected sinusoidal capillary-sized vascular channels lined by a single layer of benign cuboidal CD34(+) , CD31(+) , D2-40(-) endothelial cells, separated by loose stroma with spindle cells. One tumour was a cellular capillary haemangioma. Intravascular growth was seen in nine specimens. All haemangiomas had extramedullary haematopoiesis. Acquired cystic kidney disease (ACKD) was seen in 11 kidneys (nine patients), renal cell carcinoma (RCC) in five, ACKD-associated RCC precursors in three, Wilms' tumour in one and papillary adenomas in five.

CONCLUSIONS

Anastomosing haemangioma appears as a distinctive clinicopathological entity developing in kidneys with ESRD, with or without ACKD.