CT and MR imaging of retroperitoneal schwannoma

Beyond squamous cell carcinoma: MRI appearance of uncommon anal neoplasms and mimickers

Anal cancer is an uncommon malignancy. In addition to squamous cell carcinoma, there are a variety of other less common malignancies and benign pathologies that may afflict the anal canal, with which abdominal radiologists should be familiar. Abdominal radiologists should be familiar with the imaging features that can help distinguish different rare anal tumors beyond squamous cell carcinoma and that can aid in diagnosis therefore help steer management. This review discusses these uncommon pathologies with a focus on their imaging appearance, management, and prognosis.

Manifestations of Ovarian Cancer in Relation to Other Pelvic Diseases by MRI

Imaging plays a pivotal role in the diagnostic approach of women with suspected ovarian cancer. MRI is widely used for preoperative characterization and risk stratification of adnexal masses. While epithelial ovarian cancer (EOC) has typical findings on MRI; there are several benign and malignant pelvic conditions that may mimic its appearance on imaging. Knowledge of the origin and imaging characteristics of a pelvic mass will help radiologists diagnose ovarian cancer promptly and accurately. Finally, in special subgroups, including adolescents and gravid population, the prevalence of various ovarian tumors differs from that of the general population and there are conditions which uniquely manifest during these periods of life.

Retroperitoneal cystic schwannoma mimics liquefied hematoma

Schwannomas are nerve sheath tumors that seldom occur in the retroperitoneal region. Herein, we describe an incidentally detected retroperitoneal schwannoma that mimicked liquefied hematoma on computed tomography. A 61-year-old man was admitted to the emergency department with chest pain caused by a fall at a construction site. Chest computed tomography incidentally revealed a retroperitoneal cystic mass measuring 10 cm, in addition to multiple rib fractures and hemopneumothorax. The patient frequently consumed alcohol and had a history of repeated trauma; therefore, we considered the following 2 conditions: retroperitoneal cystic tumor and liquefied hematoma. He underwent complete surgical excision, and a histopathological examination confirmed the mass as a schwannoma. Experience and knowledge regarding the computed tomography findings of retroperitoneal cystic schwannoma are useful for the differential diagnosis of infrequent retroperitoneal tumors.

Solid Primary Retroperitoneal Masses in Adults: An Imaging Approach

Mass lesions in the retroperitoneal space may be primary or secondary. Primary retroperitoneal mass lesions are relatively uncommon as compared to pathology that arises secondarily from retroperitoneal organs. These may be solid or cystic lesions. The overlapping imaging features of various solid primary retroperitoneal tumors make the diagnosis difficult, and hence, histopathology remains the mainstay of diagnosis. This paper provides a brief review of the anatomy of the retroperitoneal space and provides an algorithmic approach based on cross-sectional imaging techniques to narrow down the differential diagnosis of solid primary retroperitoneal masses encountered in the adult population.

Mimics and Pitfalls of Primary Ovarian Malignancy Imaging

The complex anatomy and similarity of imaging features of various pathologies in the pelvis can make accurate radiology interpretation difficult. While prompt recognition of ovarian cancer remains essential, awareness of processes that mimic ovarian tumors can avoid potential misdiagnosis and unnecessary surgery. This article details the female pelvic anatomy and highlights relevant imaging features that mimic extra-ovarian tumors, to help the radiologists accurately build a differential diagnosis of a lesion occupying the adnexa.

Para-adrenal schwannoma mimicking a giant adrenal lesion

A 57-year-old man was incidentally diagnosed with a 7 cm left-sided retroperitoneal mass. The mass was presumed to be arising from the left adrenal gland on a CT scan of the adrenal glands. Thus, a thorough workup ensued, looking into the possible functionality of the lesion. All investigations resulted in the negative. Subsequently, the patient was referred for surgery to fully characterise the tumour. Histology proved that the lesion was a benign retroperitoneal schwannoma with no relation to the adrenal gland.

Decision Making in Retroperitoneal Nerve Sheath and Nerve-Associated Tumors: A Modular Approach

BACKGROUND

Surgical treatment of retroperitoneal nerve and nerve-associated tumors is challenging, especially in cases with large extent. A single surgical access may have limitations and jeopardize patients.

OBJECTIVE

To present a series of patients to illustrate our individually tailored treatment concept and decision pathway.

METHODS

Retrospectively, clinical findings and imaging were related to surgical features and outcome. An algorithm for choice of approach was established.

RESULTS

From 2012 to 2017, we operated on n = 13 patients with retroperitoneal tumors, of these n = 9 were included (n = 6 female, n = 3 male). Histological findings included n = 2 schwannomas, n = 2 malignant peripheral nerve sheath tumors, n = 1 non-origin sarcoma, n = 1 perineurioma, n = 1 intraneural ganglion cyst, n = 1 lymphoma, and n = 1 paraganglioma. In n = 6 patients, we used a monoportal (retroperitoneal/transperitoneal) approach; in n = 2 patients, a biportal retroperitoneal to inguinal/transperitoneal to dorsal approach; and in n = 1 patient, a triportal transperitoneal to dorsal to gluteal approach. In n = 2 patients, we performed an open biopsy only; in n = 2 patients, a tumor enucleation; in n = 3 patients, a subtotal function-sparing resection; in n = 1 patient, a complete resection; and in n = 1 patient, intraneural decompression. In n = 1 patient, a new motor deficit appeared. n = 4 patients required further radio-oncological treatment. n = 8/9 patients are alive without tumor progress or recurrence.

CONCLUSION

Retroperitoneal nerve or nerve-associated tumors encompass multiple entities. Depending on suspected histology and tumor extension, extensile or combined surgical approaches may be necessary. We present our algorithm for assessment and decision-making regarding surgical access ports and pathways.

Management of giant presacral schwannoma. Clinical series and literature review

PURPOSE

Presacral schwannomas are rare tumors. Due to their benign nature and slow growth, these tumors are often giant and become difficult to treat. Their removal is a surgical challenge with different strategies reported in the literature. This study presents the consecutives cases of presacral schwannomas operated on in our institution, our surgical strategy and literature review.

METHODS

This retrospective study includes all consecutive patients operated on for a pre-sacral schwannoma in our department between 2006 and 2019, i.e. 6 patients. We report clinical features, pre and post-operative imaging, surgical data and post-operative outcomes.

RESULTS

All patients had symptoms before surgery (constipation, dysuria, radicular or lower back pain) with an average duration of 7.4 months. All patients underwent an MRI and a CT scan before the surgery. Five patients had type III schwannoma according to Klimo classification and one patient had a type II. The average size was 504,9 cm³ (range 53,1-1495,4). All the patients were operated on by an anterior approach in a double team with an mean duration of 246 min. Intraoperative bleeding was less than 500 ml for 4 patients, 2 patients had significant bleeding (2700 and 2900 mL). Excision was total or subtotal in all cases. One patient had an intraoperative complication (air embolism). Follow up at 3 months was excellent with a disappearance of symptoms for all patients except one patient who retained constipation. One patient had a late complication (bowel obstruction due to tissue adhesions). At last follow-up after phone interview, no patient had clinical symptoms that could suggest a recurrence.

CONCLUSION

The anterior approach with a double surgical team is a great option for the treatment of presacral schwannoma. Combined with adequate preoperative imaging and intraoperative stimulation, it reduces the risk of intra and postoperative complications.

Update on MR Imaging of cystic retroperitoneal masses

OBJECTIVE

This article reviews the MRI appearance of cystic retroperitoneal (RP) masses.

CONCLUSION

Lymphangiomas are the most common RP cystic masses and typically appear simple; microscopic fat is a specific but insensitive finding. Location, internal complexity, and enhancement pattern suggest alternative diagnoses which range from normal anatomic variants to congenital abnormalities and importantly include benign, neurogenic, and malignant neoplasms. An approach to the MR imaging of cystic RP masses is presented.

MRI of Tumors and Tumor Mimics in the Female Pelvis: Anatomic Pelvic Space-based Approach

Pelvic masses can present a diagnostic challenge owing to the difficulty in assessing their origin and the overlap in imaging features. The majority of pelvic tumors arise from gastrointestinal or genitourinary organs, with less common sites of origin including the connective tissues, nerves, and lymphovascular structures. Lesion evaluation usually starts with clinical assessment followed by imaging, or the lesion may be an incidental finding at imaging performed for other clinical indications. Since accurate diagnosis is essential for optimal management, imaging is useful for suggesting the correct diagnosis or narrowing the differential possibilities and distinguishing tumors from their mimics. Some masses may require histologic confirmation of the diagnosis with biopsy and/or up-front surgical resection. In this case, imaging is essential for presurgical planning to assess mass size and location, evaluate the relationship to adjacent pelvic structures, and narrow differential possibilities. Pelvic US is often the first imaging modality performed in women with pelvic symptoms. While US is often useful to detect a pelvic mass, it has significant limitations in assessing masses located deep in the pelvis or near gas-filled organs. CT also has limited value in the pelvis owing to its inferior soft-tissue contrast. MRI is frequently the optimal imaging modality, as it offers both multiplanar capability and excellent soft-tissue contrast. This article highlights the normal anatomy of the pelvic spaces in the female pelvis and focuses on MRI features of common tumors and tumor mimics that arise in these spaces. It provides an interpretative algorithm for approaching an unknown pelvic lesion at MRI. It also discusses surgical management, emphasizing the value of MRI as a road map to surgery and highlighting anatomic locations where surgical resection may present a challenge. ^©RSNA, 2019.

Giant Pelvic Schwannoma: Case Report and Review of the Literature

INTRODUCTION

Pelvic schwannomas are rare, mostly benign tumors. They are usually asymptomatic until their massive growth compresses adjacent organs. We describe the case of a 53-year-old man with a pelvic schwannoma who initially complained of constipation and urinary retention.

AREAS COVERED

We analyzed the clinical presentation, histopathology, diagnostic imaging tools, and the treatment options for pelvic schwannomas, compared with the few other cases reported in the literature.

EXPERT COMMENTARY

Pelvic schwannomas are masses that can grow to considerable size, producing symptoms over time. Due to their size and localization, surgery, although difficult, is the only available treatment.

Primary myxoid liposarcoma of the pelvis: An unusual location

Myxoid liposarcoma is the second most common type of liposarcoma, normally located in deep tissues of the lower extremities and rarely in the mesenchyma of abdomen and pelvis We present a patient who, incidentally, showed a large pelvis mass. CT and MR revealed a loculated lesión with hypodense areas and very high signal in T2 respectively as well as heterogeneous contrast enhancement. The imaging findings of pelvic myxoid liposarcoma are nonspecific, but nevertheless a painless mesenchymal mass should be considered when we see lesions of myxoid aspect in the pelvic area without a clear relationship with defined anatomic structures.

Retroperitoneal cystic masses: magnetic resonance imaging features

The objective of this review is to discuss the clinical and histopathologic features, MRI characteristics, and management options of retroperitoneal cystic masses. Radiologists should be familiar with the MR imaging characteristics of retroperitoneal cystic masses to allow for a refined differential diagnosis, assist with lesion management, and prevent unnecessary invasive procedures.

Giant Invasive Sacral Schwannoma with Aortic Bifurcation Compression and Hydronephrosis

BACKGROUND

Sacral schwannomas are rare tumors arising from nerve sheath Schwann cells. They are classified into 3 types: first type schwannoma arising from the sacrum, second type schwannoma eroding the sacrum, and third type schwannoma extending extensively, involving anterior, posterior, and retroperitoneal space. Among these type 2 sacral tumors, according to Klimo's classification, an eroding sacrum extending all over posteriorly, anteriorly, and laterally is still rarer. Only 38 cases have been reported in literature reviews. Only 6 cases of giant tumors of >10 cm in any 1 dimension have been reported.

CASE DESCRIPTION

We present such a giant sacral schwannoma, with invasiveness eroding the sacrum; compressing the ureters, aortic bifurcation, bladder, and bowel; and presenting as lower abdominal pain, hydronephrosis, dysuria, and constipation. This is the first case reported in the literature that has described a large retroperitoneal tumor compressing retroperitoneal structures-aortic bifurcation vascular compression and ureter compression causing hydronephrosis.

CONCLUSIONS

Though complete resection, which caused various severe postoperative complications in the reported cases, is the best option, a less morbid procedure would be appropriate; hence we underwent subtotal excision of the tumor, with complete recovery of our patient's symptoms without neurologic deficit.

Giant Presacral Schwannoma in Man: Report of a Case with Emphasis on Imaging Findings

BACKGROUND

Schwannoma is a tumor arising from peripheral nerve sheaths and commonly occurs in the head, neck, and upper and lower extremities. Schwannoma in the presacral space is relatively rare and is often misdiagnosed before pathologic diagnosis is made.

CASE DESCRIPTION

Here we discuss a case of giant presacral schwannoma in a 34-year-old man with an emphasis on imaging findings.

CONCLUSIONS

Solid and encapsulated, round or oval, with rich blood supply may be the characteristic imaging findings of presacral schwannoma, which may narrow the differential diagnosis of hypervascular pelvic lesions.

Surgical treatment of neurofibromatosis type I followed by retroperitoneal tumor (in Russian only)

AIM

To determine the optimal surgical approach in patients with abdominal and retroperitoneal manifestations of Recklinghausen's disease.

MATERIAL AND METHODS

There were 4 patients (3 women and 1 man) with neurofibromatosis type I who were treated at Vishnevsky National Medical Research Center of Surgery.

RESULTS

There were 3 robot-assisted procedures: excision of retroperitoneal tumors (plexiform neurofibroma and schwannoma) in 2 cases and right adrenal pheochromocytoma in 1 patient. We also included 1 clinical case of conventional surgery for neurofibromatosis type I followed by multiple gastrointestinal stromal duodenal and intestinal tumors. In one case, postoperative period was complicated by fluid accumulation in the bed of previously removed tumor that required US-assisted drainage. Postoperative period was uneventful in other cases.

CONCLUSION

Robot-assisted surgery is safe and effective in patients with Recklinghausen's disease followed by single abdominal and retroperitoneal tumors. It is more expedient to choose conventional technique for multiple tumors located in different parts of retroperitoneal space or abdominal cavity.

Practical approach to primary retroperitoneal masses in adults

Primary retroperitoneal masses constitute a heterogeneous group of uncommon lesions and represent a challenge due to overlapping imaging findings. Most are malignant lesions. Although they are more prevalent in adults, they can occur at any age. Such lesions are classified as primary when they do not originate from a specific retroperitoneal organ and are divided, according to the image findings, into two major groups: solid and cystic. The clinical findings are nonspecific and vary depending on the location of the lesion in relation to adjacent structures, as well as on its behavior. The main imaging methods used for staging and surgical planning, as well as for selecting the biopsy site and guiding the biopsy procedure, are computed tomography and magnetic resonance imaging. In most cases, the treatment is challenging, because of the size of the lesions, vascular involvement, or involvement of adjacent organs. In this article, we present a review of the retroperitoneal anatomy and a practical approach to the main imaging features to be evaluated, with a view to the differential diagnosis, which can guide the clinical management.

Retroperitoneal Knee Pain: An Unusual Case Report and Review of an Ancient Schwannoma

Schwannomas are nerve sheath tumors that occur in Schwann cells. They are usually benign, but malignant transformation can occur. Symptomatology depends on the involvement of the surrounding tissues or the mass effect of the tumor. We describe a case of a 28-year-old man who initially presented with right iliac fossa pain associated with radiating pain over the anterior and lateral aspect of his right knee. Following subsequent investigations, we found a retroperitoneal schwannoma of the right lateral femoral cutaneous nerve. The key to our diagnosis was the referred pain to his right knee, which gave us a clue of possible neuropathic pain. Our patient highlights the need to consider a unified diagnosis when faced with an incongruent set of symptoms. Magnetic resonance imaging is the diagnostic modality of choice for the diagnosis of schwannomas. Treatment is directed towards symptomatic control. Surgery, radiation, and, in rare instances, chemotherapy are the major treatment modalities employed.

MR imaging features of benign retroperitoneal paragangliomas and schwannomas

Background

To determine whether MRI feature analysis can differentiate benign retroperitoneal extra-adrenal paragangliomas and schwannomas.

Methods

The MRI features of 50 patients with confirmed benign retroperitoneal extra-adrenal paragangliomas and schwannomas were retrospectively reviewed by two radiologists blinded to the histopathologic diagnosis. These features were compared between two types of tumours by use of the Mann-Whitney test and binary logistic regression. The patients’ clinical characteristics were reviewed.

Results

Analysis of MRI images from 50 patients revealed no significant differences in the quantitative MRI features of lesion size, ratio of diameter and apparent diffusion coefficient. There were significant differences in the qualitative MRI features of location, necrosis, cysts and degree of tumour enhancement for two readers, with no significant differences in the other qualitative MRI features between these tumours. The combination of necrosis with degree of tumour enhancement during the arterial phase increased the probability that a retroperitoneal mass would represent retroperitoneal extra-adrenal paraganglioma as opposed to schwannoma.

Conclusion

We have presented the largest series of MRI features of both benign retroperitoneal extra-adrenal paragangliomas and schwannomas. Some MRI features assist in the differentiation between these tumours, with imaging features consisting of necrosis and avid enhancement during the arterial phase, suggestive of retroperitoneal extra-adrenal paragangliomas.

MR imaging features of benign retroperitoneal extra-adrenal paragangliomas

The goal of this study was to retrospectively review the magnetic resonance imaging (MRI) features of retroperitoneal extra-adrenal paragangliomas and to evaluate the diagnostic capabilities of MRI. Twenty-four patients with confirmed benign retroperitoneal extra-adrenal paragangliomas who underwent preoperative MRI and surgical resection were enrolled. The patients’ clinical characteristics and MRI features were reviewed by two radiologists. There were no significant differences in the qualitative and quantitative MRI features were determined by the reviewers. High signal intensity in T2-weighted imaging (T2WI) and diffusion-weighted imaging (DWI) was observed in all tumors. In contrast T1-weighted imaging (T1WI) in the arterial phase, 83.33% of the tumors were clearly enhanced. In 87.5% of cases, a persistent enhancement pattern was observed in the venous and delayed phases, and 12.5% of tumors showed a “washout” pattern. The tumor capsule, intratumoral septum and degenerations were visualized in the tumors and may be helpful in the qualitative diagnosis of extra-adrenal paragangliomas in MRI. MRI was useful in locating the position, determining the tumor ranges and visualizing the relationship between the tumors and adjacent structures. The presence of typical clinical symptoms and positivity of biochemical tests are also important factors in making an accurate preoperative diagnosis.

Hybrid open/closed resection procedure for ancient retroperitoneal Schwannoma: case report and review of the literature

BACKGROUND

Retroperitoneal, ancient Schwannomas are rare tumors that arise from neural sheath Schwann cells. Due to their location and size, these benign tumors can become symptomatic and need surgery. Laparoscopic resection is rarely performed for retroperitoneal Schwannomas. Based on a case report and review of the literature the advantages of a laparoscopic approach are discussed.

METHODS

A case of laparoscopic resection of a retroperitoneal Schwannoma is reported. An extensive literature search was done in relation to this pathology, 16 papers were included for in depth analysis.

RESULTS

Laparoscopic surgery facilitates the dissection of the tumor from surrounding tissues due to a magnified view and optimal visualization of the tumor. Shorter hospital stay, faster recovery, better cosmetic result, less blood-loss and post-operative pain are all advantages of a laparoscopic resection. Disadvantages are a steep learning curve, higher cost and prolonged operation duration.

CONCLUSIONS

Laparoscopic resection of, even large, retroperitoneal Schwannomas is feasible. In case of vertebral invaded tumors a hybrid approach is recommended.

Clinical features and retroperitoneal laparoscopic resection of adrenal schwannoma in 19 patients

OBJECTIVE

To explore the diagnostic and therapeutic principles of the rare adrenal schwannoma.

METHODS

We objectively analyzed the detailed clinical data of 19 patients with adrenal schwannoma treated in a large comprehensive medical center in China between January 2009 and March 2014, including general information, clinical manifestations, imaging, adrenal-related endocrine tests, treatment, pathology, and follow-up records.

RESULTS

Patients included 16 females and 3 males ranging from 23 to 66 years of age (mean, 48.3 ± 12.6 years), of whom 15 were discovered incidentally. Four patients reported mild abdominal discomfort. Each patient had one unilateral lesion, ranging in diameter from 4.0 to 8.8 cm (mean, 6.2 ± 1.2 cm). Lesions were hypoechoic in 16 patients and cystic-solid in 3 patients. Computed tomography (CT) scanning revealed soft tissue density, mostly with calcifications and clear boundaries. Average values in normal and enhanced CT were 28.7 ± 7.2 Hounsfield units (HU) and 59.7 ± 5.4 HU, respectively. Indicators of adrenal-related endocrine tests were normal, except that catecholamines levels were slightly low in 2 patients with excessively large lesions. All patients underwent uncomplicated retroperitoneal laparoscopic surgery, with subsequent pathology confirmation of adrenal schwannoma. The patients have been followed for 6 months to 4 years, with no recurrence.

CONCLUSION

Our results demonstrate that the onset of adrenal schwannoma is always occult, without typical clinical manifestations and adrenal-related endocrine abnormalities, and the pre-operative diagnosis depends primarily on imaging features of hypoechoic calcifications and mild enhancement. Diagnosis can be confirmed by postoperative pathology. Even with large diameter lesions, retroperitoneal laparoscopic surgery is still the preferred approach, with good prognosis.