Intrarenal schwannoma: a report of four cases including three cellular variants

Myxoid Pseudotumor Involving the Renal Sinus: Clinicopathologic Study of 33 Cases Supporting a Distinct Benign Non-neoplastic Lesion

We describe 33 cases of myxoid pseudotumor involving the renal sinus from 31 patients. Patients included 21 men and 10 women, ages 30 to 95 years. Twenty-seven cases (82%) had an associated malignancy, including urothelial carcinoma of the renal pelvis (22 cases), clear cell renal cell carcinoma (3 cases), urothelial carcinoma of the bladder (1 case), and poorly differentiated carcinoma of uncertain lineage (1 case). The remaining 6 (18%) had no associated malignancy and included 3 nephrectomies for ureteral stricture, 2 ureteropelvic junction repairs, and 1 resection of a "periureteral mass" (subsequently shown to be myxoid pseudotumor). Myxoid pseudotumor was identified by preoperative computed tomography imaging in 2 patients (6%) and identified by the gross dissector in 9 cases (27%). The mean size was 14 mm (range: 5 to 38 mm). All cases had an admixture of adipocytes, myxoid stromal matrix, variable collagenization, and a hypocellular population of bland spindled and stellate stromal cells. No multilobated atypical stromal cells were present. Clinical follow-up was available for 28 patients (90%), ranging from 1 to 132 months (mean: 24.6 mo). No patients had adverse events related to the myxoid pseudotumor. Myxoid pseudotumor of the renal sinus is often associated with a variety of adjacent neoplastic and non-neoplastic conditions and may present as a mass lesion detectable by imaging and/or gross inspection. Awareness of this benign process is important to avoid confusion with a neoplasm, especially liposarcoma.

Renal Schwannoma: A Rare Case Report and Literature Review

Schwannomas originating in the kidney are extremely rare with very few cases documented in the literature. It is difficult to distinguish them from other common renal masses based on clinical symptoms and imaging characteristics alone, as both are non-specific for this pathology. Thus, the final diagnosis of schwannoma is typically made only after surgical resection and histologic examination. We present the case of a 66-year-old female who was initially evaluated for flank pain and referred to us after a renal mass was found on CT imaging. A partial nephrectomy was performed, and subsequent pathological examination confirmed the diagnosis of renal schwannoma.

Giant renal schwannoma with obvious hemorrhage and cystic degeneration: a case report and literature review

BACKGROUND

Renal schwannomas are very rare and are usually benign. Its clinical symptoms and imaging features are nonspecific, and the diagnosis is usually confirmed by pathology after surgical resection.

CASE PRESENTATION

A 46-year-old Chinese female was admitted to the hospital with right flank pain that had persisted for the six months prior to admission. This pain had worsened for 10 days before admission, and dyspnea occurred when she was supine and agitated. A right abdominal mass could be palpated on physical examination. Computed tomography and magnetic resonance imaging examinations revealed a large, nonenhanced, cystic and solid mass in the right kidney. The patient received radical nephrectomy for the right kidney. The diagnosis of schwannoma was confirmed by pathological examination.

CONCLUSIONS

We report a case of a large renal schwannoma with obvious hemorrhage and cystic degeneration, which can be used as a reference for further study.

FDG PET/CT in a Case With Cellular Schwannoma of the Kidney

ABSTRACT

Schwannoma of the kidney is exceedingly rare. We describe contrast-enhanced CT and FDG PET/CT findings in a case with renal cellular schwannoma. Contrast-enhanced CT showed the enhancing tumor was located in the anterior middle portion of the left kidney, encasing the renal vessels and compressing the renal pelvis. The tumor showed inhomogeneous FDG uptake with SUVmax of 8.6 mimicking renal cell carcinoma. This case indicates renal schwannoma should be included in the differential diagnosis of FDG-avid renal lesions.

Laparoscopic nephrectomy for giant benign renal schwannoma: a case report and review of literature

Benign giant renal schwannoma is rarely found and the diagnosis difficulty only depends on physical and imagological examination. Pathological examination is essential to confirm the diagnosis of renal schwannoma. Nephrectomy and tumorectomy are primary treatments for renal schwannoma. Although most of the reported patients present satisfactory outcome, however, there is still not sufficient evidence to reveal the biological characteristics and post-operation recurrence rate of renal schwannoma. Herein, we report a rare case of giant and complicated renal schwannoma. A 56-years-old female patient was admitted to the urology department due to left lower back pain for approximately 5 days. No positive signs and other special abnormalities were found. CT scan presented a soft tissue tumor with inhomogeneous enhanced in the renal hilum. Surgery was performed to excise the tumor and left renal. Renal schwannoma was confirmed by pathological examination. At the 6-month follow-up, no evidence of recurrence was found. Our present report could provide more material for further study.

Epithelioid angiosarcoma arising in schwannoma of the kidney: report of the first case and review of the literature

Background

Schwannoma and angiosarcoma are infrequent pathologies that have been rarely reported in the kidney. Angiosarcoma is an uncommon malignant tumor presenting a recognizable vascular differentiation. It can develop in any site but the most common locations include the skin, soft tissues, breast, bone, liver, and spleen while renal localization has been very rarely reported in the literature. Schwannoma is a benign peripheral nerve sheath tumor composed of cells with the immunophenotype and ultrastructural features of differentiated Schwann cells. It has a wide anatomical distribution but the most frequent locations include subcutaneous tissues of the extremities and the head and neck region and the retroperitoneal and mediastinal soft tissues. The occurrence of an angiosarcoma in a pre-existing schwannoma is an extremely rare event with <20 cases reported in worldwide literature. In the present study, a renal case of angiosarcoma arising in schwannoma is presented with a detailed review of the pertinent literature.

Case Presentation

A 56-year-old man was admitted with a few days history of lower back pain and hematuria. Abdominal ultrasound showed a mass inside the left renal medulla. Subsequent imaging investigations with computed tomography and magnetic resonance confirmed the presence of the lesion and showed a pulmonary metastasis.

Conclusions

The final histopathological examination led to the diagnosis of epithelioid angiosarcoma arising in a schwannoma. The patient came to death a few months later due to a massive hemothorax. To the best of our knowledge, the present is the first case of an angiosarcoma arising in a schwannoma of the kidney.

Retroperitoneal Schwannoma in the Renal Hilum: A Case Report

A 73-year-old male was referred to our department for further treatment of a right retroperitoneal tumor. Contrast CT showed a tumor mass measuring 33 × 26 mm in size with poor contrast enhancement. Because we were unable to rule out tumor malignancy, we planned an operation. The tumor was easily separated and removed without nephrectomy. Histological study revealed a schwannoma. It is rare for this kind of tumor to arise from the retroperitoneum (approximately 0.7% of all cases), in particular at the renal hilum. We herein report a rare case of retroperitoneal schwannoma arising from the renal hilum.

A case of renal schwannoma

Schwannomas are benign tumors that arise from the neural sheath of Schwann cells. Renal schwannomas are extremely rare and are commonly misdiagnosed as renal cell carcinoma, which typically results in a radical nephrectomy. We present a case of a renal schwannoma that mimics a renal pelvis tumor.

Cystic retroperitoneal renal hilar ancient schwannoma: Report of a rare case with atypical presentation masquerading as simple cyst

Schwannoma is a benign soft tissue tumor of neural origin arising from the Schwann cells of the neural sheath. It has rarely been reported in renal or perirenal region. The preoperative diagnosis has mostly been confused with renal cell carcinoma in this location in most previous reports. We report a case that presented with a large "simple cystic" mass at the renal hilum. The preoperative differential diagnosis included hilar renal cortical cyst, renal sinus cyst, ureteropelvic junction obstruction (UPJO), or even a hydatid cyst. The final diagnosis was clinched only on histopathological examination.

Schwannoma of the kidney

Schwannomas of the kidney are rare, with only a few reported cases. We report three additional cases with immunohistochemical analysis. All three tumors were from females (aged 27, 35, and 59 years) and ranged from 4.8 to 8 cm in diameter. All of the patients underwent nephrectomy. The tumors were totally or partially encapsulated; two were in the hilum and one was centered in the renal cortex. All tumors were diffusely positive for S100 protein. Two were positive for neuron-specific enolase. Immunostaining for neurofilament, HMB45, microphthalmia transcription factor, smooth muscle actin, CD34, cytokeratin AE1/3, cytokeratin 7, and CD10 were negative. Follow-up data were available for two patients; neither had tumor recurrence or metastasis. In conclusion, renal schwannoma is rare, usually arises centrally, impinging on the hilum or the pelvis, and is cured by resection. Sarcomatoid carcinoma and other spindle cell tumors should be considered in the differential diagnosis.

Renal Schwannoma: case report and literature review

Schwannomas are tumors arising from the nerve sheath. Renal schwannomas are extremely rare and have nonspecific symptoms and limited radiologic features, and are often diagnosed histologically after surgical excision. We report a case of a left renal schwannoma which, after evaluation by imaging studies, was assumed to be a renal cell carcinoma arising from the left kidney. A brief discussion and literature review of the diagnosis, treatment, and prognosis is presented.

Intraneural perineurioma: a systematic review with illustrative cases

CONTEXT

Intraneural perineurioma may be confused with other "onion bulb" Schwann cell entities (localized hypertrophic neuropathy, reactive/demyelinating processes, or inherited polyneuropathies of Charcot-Marie-Tooth/Dejerine Sottas) due to similar clinical, radiologic, and histologic features. Perineurial and Schwann cells can only be differentiated by ultrastructure and immunohistochemsitry.

OBJECTIVE

To identify and summarize the clinicopathologic features of true cases of intraneural perineurioma from the English language literature.

DATA SOURCES

A systematic review was performed on definitive intraneural perineuriomas identified through Medline. Baylor College of Medicine-affiliated hospitals' anatomic pathology databases yielded 2 illustrative intraneural perineurioma cases.

STUDY SELECTION

Intraneural perineurioma inclusion criteria consisted of characteristic histology and confirmation of perineurial cell lineage by either immunohistochemistry (epithelial membrane antigen positive, S100 protein negative) and/or ultrastructural analysis (thin cytoplasmic processes with an incomplete basal lamina, poorly formed tight junctions, and pinocytotic vesicles).

DATA EXTRACTION

Clinicopathologic data were extracted from all identified articles, with subsequent statistical analysis of the following parameters: age, sex, race, tumor location, tumor size, duration of symptoms prior to diagnosis, treatment modalities and outcomes measures, follow-up assessment for tumor recurrence and metastasis, clinical features (history of trauma, motor/sensory abnormalities, clinical/family history), and diagnostic workup (routine histology, immunohistochemistry, ultrastructural analysis, and molecular/cytogenetic characteristics).

CONCLUSIONS

Intraneural perineurioma is a neoplastic proliferation of perineurial cells with unique immunohistochemistry and ultrastructural features, and it is distinct from other onion bulb Schwann cell-derived entities. Despite harboring molecular abnormalities of the long arm of chromosome 22, intraneural perineurioma has not been associated with neurofibromatosis. Intraneural perineurioma is a benign peripheral nerve sheath tumor that does not recur or metastasize.

Benign Renal Schwannoma: A Case Report and Literature Review

Schwannomas are tumors arising from cells of the nerve sheath. While schwannomas are commonly found in peripheral nerves and cranial nerves, these tumors are rarely found within the kidney and may be difficult to differentiate from renal cell carcinoma. Few cases have been reported in the literature, and very little has been described regarding the imaging appearance of these rare renal tumors. We present a case of intrarenal schwannoma with sonographic, computed tomographic, and pathologic correlation.

Schwannoma of the Adrenal Gland

Primary schwannomas of the adrenal gland are extremely uncommon. We report the clinical and pathologic features of two cases, occurring in a 73-year-old man and a 26-year-old woman, both of whom presented with abdominal pain and an adrenal mass on imaging studies. Both tumors were characterized by a proliferation of cytologically bland spindle cells. One case exhibited alternating compact Antoni A areas and less cellular Antoni B areas consistent with conventional schwannoma, whereas the other case was hypercellular and composed predominantly of Antoni A areas consistent with cellular schwannoma. Reactive inflammatory cells and lymphoid aggregates were present throughout both tumors. The diagnosis of schwannoma was supported by positive immunoreactivity for S-100 protein and collagen IV and absence of reactivity for keratin, muscle related antigens, and CD34 in both cases. Electron microscopy was also performed in the case of cellular schwannoma, which showed ultrastructural features confirming the diagnosis. Both cases had a favorable outcome without evidence of recurrence or metastasis. Because of its rarity, schwannoma occurring at this particular site can pose problems in diagnosis and should be distinguished from other spindle cell lesions of the adrenal gland.

An immunohistochemical approach to the differential diagnosis of renal tumors

Renal neoplasms comprise several distinct clinicopathologic entities with potential prognostic and the rapeutic differences. Although careful morphologic examination using sections stained with hematoxylin and eosin will allow for the correct diagnosis in the majority of cases, there is sufficient overlap between several entities such that ancillary techniques may be necessary to arrive at the correct diagnosis. In routine diagnostic surgical pathology practice of renal tumors, immunohistochemistry is the foremost ancillary technique. Using an approach based on common histologic patterns (tumors with clear cytoplasm, granular cytoplasm, tubulopapillary architecture, spindle cell morphology, small round-cell morphology, and infiltrating poorly differentiated carcinoma), we will discuss the utility of immunohistochemistry in the differential diagnosis of renal neoplasms. In recent years, needle biopsies from renal masses are being increasingly performed. In these small biopsies, the entire range of cytoarchitectural features that are generally necessary to make a diagnosis may not be fully appreciated. Immunohistochemistry may be helpful in this setting to narrow the differential diagnosis or to arrive at a definitive diagnosis. Finally, the use of immunohistochemistry for the confirmation of metastatic renal cell carcinoma presenting at distant sites will be discussed. Panels of immunohistochemical stains are proposed for different settings, including renal cell carcinoma (RCC) marker, CD10, and vimentin to suggest renal origin of a metastatic tumor, and markers to aid in subclassification of RCC, including parvalbumin and c-kit for chromophobe RCC, and cytokeratin 7 and alpha-methyl-acyl-CoA racemase for papillary RCC.

[Renal neurilemoma--a rare differential diagnosis of renal tumors]

Neurilemomas originate from the Schwann cells of nerve sheaths. They can occur ubiquitously as benign or malign variants. Renal neurilemomas are extremely rare. Imaging does not allow a certain diagnosis. Complete tumor resectioning is the only curative therapy. Effective conservative treatment is not known. Histological criteria of renal neurilemoma are: mesenchymal, spindle cell, capsulated tumor intensely positive to S-100 antiserum. Epithelial markers do not react.

Intrarenal solitary fibrous tumor of the kidney report of a case with emphasis on the differential diagnosis in the wide spectrum of monomorphous spindle cell tumors of the kidney

Solitary fibrous tumor (SFT) is a neoplasm that can occur in the urogenital tract, and is also reported occurring in the spermatic cord, seminal vesicles, urinary bladder, prostate, and kidney. Furthermore, it is most important to consider its existence in the kidney, because it is usually diagnosed as renal cell carcinoma pre-operatively. To our knowledge, only 10 cases of SFT have been reported in the kidney to date. We report the clinico-pathological features of an intrarenal SFT occurring in a 31-year-old woman. The tumor, measuring 8.6 cm in its greatest diameter, completely replaced the cortex and the medulla of the middle region of the right kidney, compressing the pelvis. Radiological imaging was consistent with a renal cell carcinoma. Histologically, the tumor was composed of a proliferation of bland-looking vimentin+, CD34+, bcl2+ and CD99+ spindle cells exhibiting a haphazard to storiform growth pattern, pushing borders, and a low mitotic rate (2 mitoses x 10 HPF). We placed emphasis on the differential diagnostic problems, i.e., its differentiation from other primary monomorphous benign and malignant spindle cell tumors of the kidney, such as fibroma, benign fibrous histiocytoma, hemangiopericytoma, inflammatory myofibroblastic (pseudo-)tumor, leiomyoma, angiomyolipoma with predominant spindle cell smooth muscle component, benign peripheral nerve sheath tumors, renal mixed epithelial/stromal tumors, adult type mesoblastic nephroma, fibrous type monophasic synovial sarcoma, malignant peripheral nerve sheath tumors, fibrosarcoma, and low-grade fibromyxoid sarcoma.