Primary leiomyosarcoma of the kidney: a clinicopathologic study of 27 cases. Am J Surg Pathol. 2010;34:238-242. [PMID: 20090506 DOI: 10.1097/pas.0b013e3181cad8c9]

Sarcomatoid and Rhabdoid Renal Cell Carcinoma: Clinical, Pathologic, and Molecular Genetic Features

Renal cell carcinoma (RCC) with sarcomatoid and rhabdoid morphologies has an aggressive biological behavior and a typically poor prognosis. The current 2022 WHO classification of renal tumors does not include them as distinct histologic entities but rather as transformational changes that may arise in a background of various distinct histologic types of RCC. The sarcomatoid component shows malignant spindle cells that may grow as intersecting fascicles, which is reminiscent of pleomorphic undifferentiated sarcoma. The rhabdoid cells are epithelioid cells with eccentrically located vesicular nuclei with prominent nucleoli and large intracytoplasmic eosinophilic inclusions. Studies have shown that RCCs with sarcomatoid and rhabdoid differentiation have distinctive molecular features. Sarcomatoid RCC harbors shared genomic alterations in carcinomatous and rhabdoid components, but also enrichment of specific genomic alterations in the sarcomatoid element, suggesting molecular pathways for development of sarcomatoid growth from a common clonal ancestor. Rhabdoid differentiation also arises through clonal evolution although less is known of specific genomic alterations in rhabdoid cells. Historically, treatment has lacked efficacy, although recently immunotherapy with PD-1/PD-L1/CTLA-4 inhibitors has produced significant clinical responses. Reporting of sarcomatoid and rhabdoid features in renal cell carcinoma is required by the College of American Pathologists and the International Collaboration on Cancer Reporting. This manuscript reviews the clinical, pathologic, and molecular features of sarcomatoid RCC and rhabdoid RCC with emphasis on the morphologic features of these tumors, significance of diagnostic recognition, the molecular mechanisms of tumorigenesis and differentiation along sarcomatoid and rhabdoid lines, and advances in treatment, particularly immunotherapy.

Spindle Cell Renal Neoplasms: A Pathological Case Report on Primary Renal Leiomyosarcoma and Sarcomatoid Renal Cell Carcinoma

Renal oncopathology in adults, as a field of pathology, is dominated by a single entity - clear cell renal cell carcinoma (RCC) with other entries, such as urothelial carcinoma of the renal pelvis, angiosarcoma, and others being extremely rare. Herein, we report two histopathological cases with differential diagnoses of spindle cell renal neoplasms. The first patient, a 42-year-old male, presented with new-onset right-sided abdominal flank pain, and imaging showed a 12 cm renal tumor. Histopathology showed a spindle cell neoplasm, with significant mitotic activity and giant cell, with immunohistochemistry being positive for caldesmon and vimentin, focally for smooth muscle actin (SMA). No reaction was noted for pan-cytokeratin (CK AE1/AE3), epithelial membrane antigen (EMA), cytokeratin (CK) 7, cluster of differentiation (CD) 117, soluble 100 protein (S100), human melanoma black (HMB) 45, Melan A, CD10, and desmin. Due to peculiar histomorphology and the immunophenotype, the tumor was interpreted as primary renal leiomyosarcoma. Due to continuous outpatient consultations, treatment initiation was delayed, and three months later, the patient had already developed an 87 mm local recurrence and liver metastasis. The second patient, a 53-year-old male, presented to our institution for consultation of an already excised renal tumor, diagnosed as an incidental finding on a prophylactic abdominal ultrasound. The tumor presented for consultation histologically grew as intertwining bundles of spindle cells with polymorphic hyperchromic nuclei with prominent nucleoli and had extensive areas with necrosis. Immunohistochemically, the tumor diffusely expressed CK AE1/AE3 and caldesmon and had a patchy reaction for EMA and CD10. The SMA, desmin, CD117, and CK7 reactions were negative; hence, the tumor was interpreted as a spindle cell variety (sub-type) of clear RCC.

Renal Leiomyosarcoma: Unraveling the Mysteries of a Rare Malignancy

Primary leiomyosarcoma is a rare malignant kidney tumor. The diagnosis of this disease is usually made on the basis of histological examination because it lacks specific clinical or radiological characteristics. Differentiation between leiomyosarcoma and sarcomatoid renal cell carcinoma can be challenging because spindle cell morphology is observed in both tumors. Therefore, caution should be exercised when making a diagnosis of primary renal leiomyosarcoma. Both renal sarcoma and sarcomatoid renal cell carcinoma have a worse prognosis, and nephrectomy is the treatment of choice in locally resectable tumors. An example of such a tumor is discussed in relation to its diagnostic challenges. We report a case of a 35-year-old female who presented with a left renal mass. A left radical nephrectomy was performed, and a firm, tan-white, lobulated tumor (14x8x7.5 cm) was present on gross examination. A histological diagnosis of high-grade leiomyosarcoma was made on the basis of histology, positivity for caldesmon and desmin, and negative cytokeratin immunostaining. Sarcomatoid renal cell carcinoma was ruled out based on morphological findings after extensive sampling of the tumor along with negativity for CK, CD-10, and carbonic anhydrase IX immunostaining.

Primary renal myxoid liposarcoma with pancreatic invasion on 18F-FDG PET/CT: first case report and literature review

Background

Myxoid liposarcoma (MLS) is a rare malignant soft tissue sarcoma that predominantly manifests in the deep soft tissues of the extremities, particularly within the musculature of the thigh. Unlike other types of liposarcoma, MLS demonstrates a propensity for metastasis to atypical sites, including the lung parenchyma, soft tissues, retroperitoneum, mediastinum, breast, liver, thymus, lymph nodes, and bones. The definitive diagnosis primarily relies on histology with HE staining. Imaging modalities such as ultrasound, CT, MRI, and 18F-FDG PET/CT scans serve as valuable tools for tumor identification.

Case report

A 57-year-old man presented with symptoms of abdominal distention and vomiting 1 month ago. Contrast-enhancement CT revealed a heterogeneous hypodense mass in the upper-middle part of the left kidney, displaying irregular morphology and protrusion towards the exterior of the kidney, with abundant blood supply and had a maximum dimension of approximately 10.7 cm × 9.0 cm. Additionally, a rounded soft tissue density was identified in the pancreatic body. Multiplanar reconstruction demonstrated a connection between the pancreatic lesion and the kidney mass. 18F-FDG PET/CT was conducted for staging, revealing significant growth of the lesion in the upper-middle part of the left kidney, extending beyond the kidney and infiltrating the pancreatic body. The lesion demonstrated remarkably high 18F-FDG uptake (SUVmax = 10.2, MTV = 136.13 cm3, TLG = 484.62). The postoperative pathological examination confirmed the diagnosis of MLS. On the 10th day post-surgery, the patient presented with tumor recurrence and underwent another surgical resection. Unfortunately, during the operation, the patient experienced a sudden cardiac arrest and died.

Conclusion

Renal MLS with invasion into the pancreas is very rare in clinical practice. Due to the limited research on the utilization of 18F-FDG PET/CT in this particular context, given the rarity and low incidence of MLS, its role remains largely unexplored. As PET/CT imaging becomes increasingly prevalent, thorough imaging of disease sites becomes indispensable for the development of treatment protocols and the monitoring of treatment response.

Primary renal leiomyosarcoma with a tumor thrombus in the inferior vena cava

INTRODUCTION

We report a rare case of primary renal leiomyosarcoma with a tumor thrombus in the inferior vena cava.

CASE PRESENTATION

A 54-year-old woman presented with right flank pain and abdominal distension. Physical examination findings were unremarkable. Abdominal computed tomography revealed a heterogeneously enhancing right solid renal mass with a thrombus in the renal vein extending into the inferior vena cava. Magnetic resonance imaging demonstrated a renal tumor with a thrombus about 4 cm below the hepatic vein. Chest computed tomography and bone scintigraphy were negative. The patient underwent right radical nephrectomy and vena cava thrombectomy. Histophathologic evaluation of the resected tumor confirmed the diagnosis of leiomyosarcoma. She underwent no adjuvant therapy. Seven months after surgery, the patient died following a 2-month history of multiple pulmonary and hepatic metastases.

CONCLUSION

This report highlights the importance of considering the possibility of renal leiomyosarcoma invasion to the inferior vena cava, similar to renal cell carcinoma.

Clinicopathological Characteristics and Survival Outcomes of Primary Renal Leiomyosarcoma

Background: Primary renal leiomyosarcoma (LMS) is an exceedingly rare entity with a poor prognosis. We summarized the clinicopathological characteristics, treatment choice, and survival outcomes of LMS from the Surveillance, Epidemiology, and End Results (SEER) database.

Methods: Renal LMS and kidney renal clear cell carcinoma (KIRC) data from 1998 to 2016 were collected from the SEER database. The continuous variables were analyzed using t-tests, while the categorical variables were analyzed using Pearson's chi-squared or Fisher's exact tests. Propensity score matching (PSM) was also performed. The cancer-specific survival (CSS) and overall survival (OS) curves were estimated using Kaplan-Meier analyses and compared by log-rank tests. The risk factors for CSS and OS were estimated using univariable and multivariable Cox proportional hazard regression models.

Results: A total of 140 patients with renal LMS and 75,401 patients with KIRC were enrolled. These groups differed significantly in sex, race, tumor size, grade, SEER stage, surgery, radiation, and chemotherapy. Renal LMS exhibited poorer CSS and OS compared with KIRC before and after PSM. For renal LMS, the univariate Cox proportional hazard regression model indicated that larger tumor size, higher tumor grade, higher SEER stage, and chemotherapy were risk factors for CSS and OS, while surgery appeared to be a protective factor. However, only tumor grade, SEER stage, and receiving surgery remained independent prognostic factors in the multivariable Cox proportional hazard regression model. In addition, subgroup analyses indicated that surgery remained a protective factor for advanced renal LMS. However, there was no survival benefit for patients receiving chemotherapy.

Conclusions: Primary renal LMS is an exceedingly rare entity with distinct clinicopathological features and a poor prognosis. A higher tumor grade and late stage may indicate a poor prognosis. Complete tumor resection remains to be the first treatment choice, while chemotherapy may be a palliative treatment for patients with advanced disease.

Xeroderma pigmentosum and renal leiomyosarcoma: A very rare case report association

INTRODUCTION

Xeroderma pigmentosum (XP) is a rare genetic disorder causing extreme sensitivity to ultraviolet (UV) rays. It is transmitted by an autosomal recessive mode. This disease is classically characterized by a high risk of skin cancer. The occurrence of extra-dermatological cancers in patients followed for XP has been rarely reported in the literature. We present the case of a 14-year-old adolescent with an exceptional association of XP and renal leiomyosarcoma.

PRESENTATION OF CASE

A 14-year-old adolescent was presented with an abdominal mass revealed by hematuria and abdominal pain. Computed tomography (CT) of the abdomen showed an enhancing, heterogeneous right renal mass, consistent with the features of renal tumor. After non conclusive biopsy, a total nephrectomy of the right kidney was performed. Based on gross specimen observation and immunochemical analysis, the patient was diagnosed with high-grade renal leiomyosarcoma. An adjuvant chemotherapy was indicated and the patient was referred to medical oncology. At 12 months follow-up, the patient is in total remission; The CT scan did not show any locoregional or distant recurrence CONCLUSION: The risk of renal tumor is increased in patients followed for XP. Attending physicians should ask for renal imaging at the slightest sign of clinical call.

Concurrent renal cell carcinoma and hematologic malignancies: Nine case reports

BACKGROUND

The presence of renal cell carcinoma (RCC) and hematologic malignancies (HM) in the same patient is rarely observed. Three primary findings have been described in these patients, including male gender and lymphoid malignancy predominance, and the HM are usually diagnosed before or simultaneously with the RCC. There is a lack of evidence about clinical outcomes in this setting. We report the common characteristics of 9 patients diagnosed with concurrent RCC and HM and their clinical course and response to treatment.

CASE SUMMARY

Four (44%) patients were diagnosed with RCC prior to the HM, the diagnosis was simultaneous in 4 (44%) patients, and 1 (11%) patient was diagnosed with the HM prior to the RCC. No patients were treated with cytotoxic chemotherapy or radiation between the diagnosis of RCC and HM. Several unique features were seen in our case series, such as 3 simultaneous cancers in 1 (11%) patient, a splenectomy leading to remission of diffuse large B cell lymphoma without the use of chemotherapy in 1 (11%) patient, chemotherapy and rituximab for lymphoma resulting in a complete response in primary RCC in 1 (11%) patient, and immunotherapy providing an excellent response for primary renal leiomyosarcoma in 1 (11%) patient.

CONCLUSION

These findings highlight the potential role of immune system dysregulation in patients with the diagnosis of RCC and HM whereby the first malignancy predisposes to the second through an immunomodulatory effect. HM have the potential of being confused with lymph node metastasis from kidney cancer. Lymph node biopsy may be necessary at the time of initial diagnosis or in cases of mixed response to therapy. Long-term medical surveillance is warranted when a patient is diagnosed with RCC or HM. Clinicians should be aware of the higher prevalence of male gender and lymphoid malignancy with concurrent RCC and HM and that either of these conditions may be diagnosed first or they may be diagnosed simultaneously.

Primary Renal Leiomyosarcoma Arising from Renal Vein: A Case Report of Rare Entity with Review of Literature

Primary renal sarcomas are extremely rare neoplasms accounting for about 1% of all malignant renal neoplasms. Among all the sarcomas of kidney, leiomyosarcoma is the most common histotype. The histogenesis of these tumors is unclear, and presumably, they arise either from renal capsule or smooth muscle of renal vessels or renal pelvis. We report a case of a 65-year-old woman, who presented with intermittent abdominal pain for 1 year. The correct diagnosis was established only after the histopathological analysis of the resected specimen. The poor prognosis borne by these tumors mandates a thorough evaluation of all renal masses with unusual gross and histomorphology.

Primary leiomyosarcoma of kidney with metastasis to contralateral kidney. Case report

INTRODUCTION

Renal leiomyosarcoma is a rare entity in the world and its understanding is based on reports and various cases; however, the prognosis is bleak for its malignant potential and an average survival of 18 months.

CLINICAL CASE

A 54-year-old woman with a clinical picture of 6 months of pain in the right flank and a tomographic image of a bilateral renal lesion underwent right radical nephrectomy and left conservative surgery. The definitive histopathological study reported right primary renal leiomyosarcoma with left metastasis.

CONCLUSION

Renal leiomyosarcoma is an entity of low incidence and high mortality; however, our case represents the minority of patients with contralateral kidney metastasis reported in the literature.

Primary Renal Leiomyosarcoma Presenting with Subcutaneous and Osseous Metastases: Staging and Follow-Up with 18F-FDG PET/CT

A 60 year old woman who presented with multiple small subcutaneous nodules in the upper back and arms, was referred for an [18F] fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) after histological evaluation revealed metastatic leiomyosarcoma of unknown origin. The PET/CT showed multiple 18F-FDG-avid subcutaneous nodules, bone lesions, as well as a large left renal mass, which was biopsied to confirm a primary renal leiomyosarcoma arising from the renal parenchyma. A post therapy PET/CT showed overall progression of disease. The use of 18F-FDG PET/CT in the staging and evaluation of response to therapy of a renal leiomyosarcoma has not been previously described in the literature.

Renal Leiomyoma and Leiomyosarcoma: A Study of 57 Cases

Primary renal leiomyomas and leiomyosarcomas are rare, and there is a paucity of data regarding the pathologic features and outcomes of patients with these tumors. The objective of this study was to review a large series of renal smooth muscle tumors, in order to more fully elucidate their natural histories. Fifty-seven renal smooth muscle tumors were reviewed for various histopathologic features, and leiomyosarcomas were graded using the French Federation of Cancer Centers (FNCLCC) system. Tumor cores in tissue microarrays were evaluated for smooth muscle actin, desmin, h-caldesmon, calponin, myogenin, cytokeratin (OSCAR), CD117, Ki67, estrogen receptor (ER), progesterone receptor (PR), and Wilms tumor 1 (WT1). Leiomyomas were selected on the basis of preexisting diagnostic criteria, which included a lack of cytologic atypia, necrosis, and mitotic activity (0 to 1 mitoses/10 hpf). These were found to have a strong predilection for women, tended to arise from the renal capsule, were small (mean size, 4.2 cm), and had a low Ki67 proliferative rate (mean 1.4%). In addition, they uniformly expressed all smooth muscle markers and were ER/PR/WT1 positive in nearly all cases. In 10 patients with clinical follow-up, none had a tumor recurrence. In contrast, leiomyosarcomas had an equal sex distribution, were larger (mean size, 9.8 cm), had significantly higher mitotic activity (mean 8.6 mitoses/10 hpf), with most being FNCLCC grade 2. Leiomyosarcomas expressed at least 1 muscle marker, higher Ki67 proliferative activity (mean 20.4%) than leiomyomas, and most were ER/PR/WT1 negative. Tumor recurrence occurred in 65% of patients, and 35% of patients died of disease. This study therefore validates existing criteria to distinguish between leiomyomas and leiomyosarcomas.

Recurrent renal giant leiomyosarcoma

Primary renal leiomyosarcomas are rare, aggressive tumors. They constitute 1-2% of adult malignant renal tumors. Although leiomyosarcomas are the most common histological type (50-60%) of renal sarcomas, information on renal leiomyosarcoma is limited. Local or systemic recurrences are common. The radiological appearance of renal leiomyosarcomas is not specific, therefore renal leiomyosarcoma cannot be distinguished from renal cell carcinoma by imaging methods in all patients. A 74-year-old female patient presented to our clinic complaining of a palpable mass on the right side of her abdomen in November 2012. The abdominal magnetic resonance imaging revealed a mass, 25 × 24 × 23 cm in size. Her past medical history revealed that she has undergone right radical nephrectomy in 2007, due to a 11 × 12 × 13 cm renal mass that was then reported as renal cell carcinoma on abdominal magnetic resonance imaging, but the pathological diagnosis was low-grade renal leiomyosarcoma. The most recent follow-up of the patient was in 2011, with no signs of local recurrence or distant metastases within this four-year period. The patient underwent laparotomy on November 2012, and a 35 cm retroperitoneal mass was excised. The pathological examination of the mass was reported as high-grade leiomyosarcoma. The formation of this giant retroperitoneal mass in 1 year can be explained by the transformation of the lesion's pathology from low-grade to a high-grade tumor.

Magnetic Resonance Imaging of Perirenal Pathology

The perirenal space can be involved by a variety of neoplastic, inflammatory, infectious, and proliferative disorders. Magnetic resonance imaging is often an ideal technique for identification and staging of lesions arising within the perirenal space, with its superior soft tissue characterization as well as its ability to visualize extension into blood vessels and adjacent organs. This pictorial essay describes the magnetic resonance imaging appearance of a variety of pathologies which can arise from or involve the perirenal space, and provides a framework for categorization and differential diagnosis of these lesions.

Clinicopathologic characteristics and survival for adult renal sarcoma: A population-based study

INTRODUCTION

To analyze the association of clinicopathologic characteristics and treatment modality with survival among adult patients with renal sarcoma.

METHODS

We identified 489 adults diagnosed with renal sarcoma from the Surveillance, Epidemiology and End Results registry between 1973 and 2011. Cancer-specific survival was estimated using the Kaplan-Meier method and was compared between groups with log rank and Cox models.

RESULTS

Median age at diagnosis was 61 years, while median tumor size was 11 cm. Tumor histology was leiomyosarcoma in 175, liposarcoma in 100, other subtypes in 129, and unknown in 85 cases. Tumor stage at diagnosis was nonmetastatic in 322 (67%) and metastatic in 167 (33%) cases. Treatment of nonmetastatic disease was surgical resection in 171 patients, radiation in 24, both in 35, neither in 18, and unknown in 74 cases. Treatment of metastatic disease was surgery in 39 patients, radiation in 27, both in 11, neither in 42, and unknown in 48. For nonmetastatic and metastatic disease, 5-year cancer-specific survival rates were 58% and 16%, respectively. On multivariable analysis, surgery was associated with decreased cancer-specific mortality among both patients with nonmetastatic disease (hazard ratio = 0.34; 95% CI: 0.14-0.85) and those with metastatic disease (hazard ratio = 0.38; 95% CI: 0.18-0.77). Age, race, tumor size, and tumor grade were independently associated with cancer death in nonmetastatic disease, whereas race and tumor histology remained associated with mortality in metastatic disease (all P < 0.05).

CONCLUSION

Although metastatic renal sarcoma has an ominous prognosis, durable survival may be achieved for localized tumors. Although we recognize the potential for selection bias, our results suggest an association between surgical resection and decreased mortality for both nonmetastatic and metastatic renal sarcoma.

Pleomorphic leiomyosarcoma with a dedifferentiation-like appearance in the kidney: case report and literature review

Although primary leiomyosarcoma of the kidney is extremely rare, it is the most common sarcoma of the kidney. Leiomyosarcoma with a large pleomorphic component is designated as pleomorphic leiomyosarcoma. The pleomorphic component is usually similar to undifferentiated high-grade pleomorphic sarcoma, although it variably expresses smooth muscle markers on immunohistochemistry. In the few reported cases of pleomorphic leiomyosarcoma of the kidney, cases with the pleomorphic component showing distinct nodularity similar to dedifferentiated leiomyosarcoma have not been described, to the best of our knowledge. Herein, we present a case of a 49-year-old woman with pleomorphic leiomyosarcoma in the kidney showing distinct nodularity of smooth muscle marker-expressing pleomorphic cells within a background of classic leiomyosarcoma. Along with the classification as a pleomorphic leiomyosarcoma, suggesting aggressive clinical behavior, the renal origin itself might also be a predictor of poor prognosis, as shown in a previous study. This case also involved concomitant distant metastases, already present during the initial detection of the renal tumor.

Renal leiomyoma: a contemporary multi-institution study of an infrequent and frequently misclassified neoplasm

Renal leiomyoma is an exceptionally rare benign mesenchymal tumor of the kidney predominantly arising in proximity of the renal capsule or pelvis. Its rarity and nonspecific clinical and imaging features may lead to radical or partial nephrectomy on the basis of preoperative suspicion of renal cell carcinoma. The diagnosis of renal leiomyoma is challenging because of the histologic overlap with lipid-poor angiomyolipoma (AML). We conducted a multi-institution study to characterize renal leiomyoma in greater detail. We collected and reviewed 24 cases diagnosed initially as renal leiomyoma in 10 institutions from North America, Canada, and Europe. Immunohistochemical expression of desmin, HMB-45, estrogen receptor (ER), progesterone receptor (PR), and cathepsin K was evaluated. Upon central review, 9 tumors were classified as renal leiomyoma, whereas the remaining were reclassified as AML (n=13), myolipoma (n=1), and medullary fibroma (n=1). All renal leiomyomas were solitary and occurred in female patients (mean age 63 y; range, 44 to 74 y). Tumor size ranged from 0.6 to 7.0 cm (mean 2.9 cm); 7 originated from the renal capsule or the subcapsular area and 1 from a large vessel in the renal sinus. All leiomyomas were diffusely positive for desmin and negative for HMB-45 and cathepsin K; 6/9 (67%) showed diffuse ER and PR expression, and 1 case showed focal ER positivity only. Renal leiomyoma should be included in the histologic differential diagnosis of solid renal masses, particularly in perimenopausal women. The main differential diagnosis is with lipid-poor AML, and cathepsin K plays a key role in distinguishing these 2 lesions.

Renal leiomyosarcoma with soft tissue metastasis: An unusual presentation

Primary renal sarcomas are exceptionally rare, constituting 1% of all malignant renal tumours. Since the prognosis for a renal sarcoma is particularly poor, differentiation from sarcomatoid renal cell carcinoma (RCC) is necessary. Histopathology and immunohistochemistry are the only modes of diagnosing these sarcomas as they have no specific features clinically and radiologically. We report a case of renal leiomyosarcoma which was clinically diagnosed as RCC. Histopathology revealed a spindle cell sarcoma and immunohistochemistry (IHC) confirmed a renal leiomyosarcoma. She also had a liver nodule and mass in the right side of neck and left arm. Biopsy from these sites revealed a similar morphology and IHC confirmed leiomyosarcoma. We report a case illustrating the rarity of this disease and its aggressive nature owing to fatal metastatic potential.

Renal Leiomyosarcoma: Case Report and Review of the Literature

Leiomyosarcoma of the kidney is a rare entity, and our understanding of this type of renal sarcomas is limited. A 46-year-old Caucasian male presented with a chief complaint of right flank pain for one month. He came to our facility for an additional opinion regarding the management of his renal mass. Computed tomography (CT) of the abdomen showed an enhancing, heterogeneous right renal mass, consistent with the features of renal cell carcinoma (RCC). Robotic-assisted total nephrectomy of the right kidney revealed a tan mass with central necrosis that involved the upper pole of the kidney. Based on gross specimen observation and immunochemical analysis, the patient was diagnosed with high-grade leiomyosarcoma. While the prognosis is poor, radical nephrectomy remains the treatment of choice. The potential benefits of adjuvant therapy should be discussed with selected patients.

Renal leiomyosarcoma: a diagnostic challenge

Renal leiomyosarcoma is a very rare tumor that clinically and radiographically mimics more common renal malignancies. The infrequency of the condition makes it very difficult to diagnose. A 70-year-old male smoker presented with months of hematuria, right-sided flank pain, and weight loss. Imaging revealed a 3.8-centimeter renal mass that had characteristics similar to renal cell carcinoma. Initial biopsy of the mass was negative for malignancy. Two months later, subsequent imaging revealed what appeared to be metastatic bone lesions. Again, a biopsy of one of the lesions was negative for malignancy. Subsequent ureteral pyeloscopy, ureteroscopic renal pelvis biopsy, and brush cytology were negative for malignancy as well. The decision was made to perform nephrectomy for the removal of the mass. Pathologic analysis revealed renal leiomyosarcoma. This case illustrates the difficulty in diagnosing renal leiomyosarcoma. Repeated pathologic sampling was negative because of the tumor heterogeneity. Prompt diagnosis and treatment are very significant as surgical resection at an early stage offers the best prognosis.

Primary renal leiomyosarcoma: A diagnostic challenge

Primary leiomyosarcoma is an extremely rare entity constituting only 0.5-1% of all invasive renal tumors. It is frequently diagnosed on histological examination because it does not have any specific diagnostic features clinically and radiologically. At times, it is difficult to differentiate leiomyosarcoma from the sarcomatoid renal cell carcinoma even in histopathology as both the tumors have spindle-shaped atypical cells. Moreover, some epithelial markers can be present in pure smooth muscle sarcomas, while some smooth muscle markers are positive in carcinomas. Hence, a diagnosis of primary renal leiomyosarcoma should be made with caution. Since the prognosis for a renal sarcoma is particularly poor, differentiation from sarcomatoid renal cell carcinoma is necessary. The diagnostic challenge of one such tumor is discussed.

Beyond renal cell carcinoma: rare and unusual renal masses

The vast majority of primary renal masses represent clear cell or papillary renal cell carcinomas, angiomyolipomas, or transitional cell carcinomas. However, a number of more rare masses can also be encountered, many of which can be very difficult to differentiate from these more common entities based on their imaging features. These uncommon entities include metanephric adenoma, epithelioid angiomyolipoma, medullary renal cell carcinomas, multilocular cystic nephroma, hemangiopericytoma, hemangioma, leiomyoma, leiomyosarcoma, solitary fibrous tumor, renal plasmacytomas, and mixed epithelial and stromal tumors. In some cases, certain clinical and imaging features can allow one of these unusual entities to be placed in the differential diagnosis, including patient age, degree of tumor enhancement, presence of underlying sickle cell trait or sickle cell disease, the presence of a cystic component to the tumor, and tumor morphology. Even if a radiologist is unable to make a specific diagnosis, knowledge of these entities is important, as it allows radiologists to guide post-surgical follow-up, as well to understand the most common sites of metastatic disease.

Diagnosis and treatment of primary adult renal sarcoma

OBJECTIVE

To investigate the clinical characteristics of primary adult renal sarcoma.

METHODS

A total of 1654 cases with adult renal tumors were treated during 1985 to 2009 in Peking Union Medical College Hospital. Of all, 17 cases were diagnosed as primary renal sarcoma and underwent radical nephrectomy. The clinical features of 17 such patients were retrospectively analyzed.

RESULTS

The first symptom of 10 (59%) cases in all renal sarcomas was abdominal mass. The pathological diagnosis was leiomyosarcoma (7 cases), rhabdomyosarcoma (2 cases), malignant fibrous histiocytoma (2 cases), low-differentiated sarcoma (2 cases), chromophobe renal cell carcinoma coexisting with liposarcoma (1 case), fibrosarcoma (1 case), embryonic sarcoma (1 case) and leiomyosarcoma (1 case). One patient died of tumor thrombus of the inferior vena cava during surgery. Finally, 15 cases were regularly followed up for 4 to 60 months. Till now, 1 had tumor-free survival for 9 months, and the other 14 cases died 2-38 months after the operation with a median survival time of 18 (range, 5-60) months. The median survival time of leiomyosarcoma group was 28 (range, 11-60) months, and 2 cases of malignant fibrous histiocytoma died 4 and 8 months after the operation respectively.

CONCLUSIONS

The primary renal sarcoma has the clinical symptom similar with advanced renal cell carcinoma and has poor prognosis. Leiomyosarcoma might have relative good prognosis.

Recurrent renal leiomyosarcoma mimicking a colonic submucosal tumor: a case report

A primary leiomyosarcoma of the kidney is a rare, but highly aggressive, neoplasm, accounting for only 0.1% of all invasive renal tumors. Local or systemic recurrence is common, but a leiomyosarcoma is difficult to diagnose preoperatively. We recently encountered an interesting case of an unusual recurrence of a renal leiomyosarcoma. A 57-year-old woman visited our hospital complaining of lower abdominal pain. Four years previously, she had undergone a left nephrectomy. She had a primary leiomyosarcoma of the kidney that had been misdiagnosed as a renal cell carcinoma. Colonoscopy revealed the presence of a lesion similar to a submucosal tumor in the descending colon. Postoperative pathologic examination confirmed that the mass was a recurrent leiomyosarcoma. We report this unusual case and present a review of the literature.