Mucinous cystadenoma of pancreas with honeycombing appearance: Radiological-Pathological correlation

Most mucinous cystadenomas of pancreas are solitary and multilocular with a few large compartments. Serous cystadenomas usually have a polycystic or microcystic (honeycomb) pattern consisting of collection of cysts (usually >6) that range from few millimetres up to 2 cm in size. Here we present a case of mucinous cystadenoma of pancreas showing an unusual appearance of honeycombing (which has not been described so far) using imaging studies such as endoscopic ultrasound and computed tomography with histopathological confirmation of the diagnosis.

Cystic Appearance on Imaging Methods (Bosniak III-IV) in Histologically Confirmed Papillary Renal Cell Carcinoma is Mainly Characteristic of Papillary Renal Cell Carcinoma Type 1 and Might Predict a Relatively Indolent Behavior of Papillary Renal Cell Carcinoma

AIM

The aim of this study was to determine the proportion of cystic tumors according to preoperative CT (Bosniak III, IV) among surgically treated patients with histologically confirmed papillary renal cell carcinoma (pRCC) and to assess progression rates among patients with and without cystic appearance on imaging.

METHODS

A total of 138 patients with pRCC histology surgically treated in the period of January 2007-March 2017 were included. Clinical and radiological characteristics, type of surgery, histopathology results, and follow-up data were recorded and statistically evaluated.

RESULTS

Forty-one cases (29.7%) of cystic lesions (10× BIIF, 14× BIII, 17× BIV) were detected by CT. Patients with pRCC1 significantly more frequently presented with cystic appearance on CT (33/78; 42.3%) in comparison to other papillary types (8/60; 13.3%; p = 0.0002). During a median follow-up time of 49.4 months, only 2 patients with cystic lesions progressed after surgery.

CONCLUSIONS

Cystic appearance on imaging methods is mainly a characteristic of pRCC1 (42.3%). Cystic morphology on imaging might predict a relatively indolent behavior of all pRCC types. Preoperative scoring systems including tumor growth patterns (cystic vs. solid) are needed for further classification.

Brain metastases from adenocarcinoma of the lung with truly cystic magnetic resonance imaging appearance

Metastatic disease represents over half of all malignancies in brain parenchyma, and carcinoma when metastatic will often spread to the brain, with lung and breast tumors being the most common culprits. The suggestive features of metastatic disease on magnetic resonance imaging include peritumoral, vasogenic edema and avid postcontrast enhancement. We present the case of a 50-year-old male with an established diagnosis of metastatic adenocarcinoma of the lung treated with erlotinib who developed multiple cystic brain lesions on surveillance MRI. These cysts demonstrated T2 prolongation, suppressed completely on FLAIR, lacked surrounding edema, and featured a complete lack of enhancement. Due to the ambiguous imaging findings, brain biopsy was performed to establish the diagnosis. The pathology revealed a single layer of malignant cells lining brain parenchyma and focal areas of glandular growth. The intracranial lesions responded well to total brain radiation. This case is unique for the imaging findings most characteristic of simple cysts in biopsy-proven metastatic disease and may relate to the effects of erlotinib on metastatic brain tumors.

Eosinophilic solid and cystic renal cell carcinoma mimicking epithelioid angiomyolipoma: series of 4 primary tumors and 2 metastases

Eosinophilic solid and cystic renal cell carcinoma (ESC-RCC) is a novel entity of rare tumors with rather unique morphology and immunohistochemical profile. Until recently these tumors were characterized by indolent behavior. Herein, we describe a series of six primary and metastatic ESC-RCCs morphologically and immunophenotypically mimicking epithelioid angiomyolipoma (eAML). Retrospective review of unclassified RCCs with oncocytic phenotype yielded several candidate cases, 4 of which fulfilled diagnostic criteria after additional work-up. Three female patients and one male (median age 46) presented with unifocal tumors ranging from 1.5 cm to 20.5 cm (median 5 cm). On follow-up (median 32 months), 2 younger patients had no signs of tumor recurrence, but older patients presented with advanced disease. A 50 year-old female developed numerous bone metastases and tumor progression despite aggressive treatment. Two of these metastases were analyzed showing morphology and immunoprofile similar to the primary tumor. 50 year-old male had locally aggressive tumor invading adrenal gland and retroperitoneum. All cases exhibited ESC-like architecture of solid sheets, tight nests and variably sized cysts with hobnailed lining, as well as foci of diffuse growth with poorly cohesive brightly eosinophilic cells. Characteristic cytoplasmic stippling and coarse granularity was present in all cases including compact cytoplasmic "Leishmaniasis-like" globules. Due to high suspicion of eAML, immunostaining panels included melanocytic markers, cytokeratins and RCC-specific markers. All ESC-RCC were positive for CK20 and melanocytic markers Melan-A, Cathepsin-K or HMB45, as well as PAX8, whereas EMA, pan-cytokeratin, CK7, CKIT, CD10, CAIX were negative. Comparison with 5 eAML cases including 2 malignant tumors showed similar morphology and immune reactivity except for more frequent expression of HMB45 and lack of PAX8 positivity. In conclusion, we report 2 cases of aggressive ESC-RCC course including widespread bone metastases in addition to 2 typical indolent tumors. ESC-RCC and eAML could present with overlapping morphology and immunophenotype causing diagnostic difficulty and expanding our understanding of these rare tumors.

Pituitary xanthogranulomas: clinical features, radiological appearances and post-operative outcomes

BACKGROUND

Xanthogranulomas are inflammatory masses most commonly found at peripheral sites such as the skin. Sellar and parasellar xanthogranulomas are rare and present a diagnostic challenge as they are difficult to differentiate from other sellar lesions such as craniopharyngiomas and Rathke's cleft cysts pre-operatively. Their radiological imaging features are yet to be clearly defined, and clinical outcomes after surgery are also uncertain. This study reviews clinical presentation, radiological appearances, and clinical outcomes in a cohort of patients with pituitary xanthogranulomas.

METHODS

A prospectively maintained pituitary surgery database was screened for histologically confirmed pituitary xanthogranulomas between May 2011-December 2016. Retrospective case note assessments were then performed by three independent reviewers. Patient demographics, clinical presentations, imaging, and clinical outcomes were analysed.

RESULTS

During the study period 295 endoscopic endonasal pituitary surgeries were performed. Six patients had confirmed pituitary xanthogranulomas (2%). Patients most commonly presented with visual field deficits and/or endocrine dysfunction. Common imaging features included: a cystic consistency, hyperintensity on T1-weighted MR images, and contrast enhancement either peripherally (n = 3) or homogenously (n = 3). The most common pre-operative endocrine deficits were hyperprolactinaemia and hypoadrenalism (at least one of which was identified in 4/6 patients; 66%). Thirty-three percent (2/6) of patients presented with diabetes insipidus. The most common post-operative endocrinological deficits were adrenocortical dysfunction (66%) and gonadotropin deficiency (66%). Visual assessments normalised in all six patients post-operatively. Gross total resection was achieved in all patients, and at median follow up of 33.5 months there were no cases of tumour recurrence.

CONCLUSIONS

The prevalence of pituitary xanthogranulomas in our series is higher than that suggested in the literature. Surgery restored normal vision to all cases, however four patients (67%) required long-term hormonal replacement post-operatively. Imaging features such peripheral rim enhancement, a suprasellar tumour epicentre, and the absence of both calcification or cavernous sinus invasion were identified as potential indicators that together should alert clinicians to the possibility of pituitary xanthogranuloma when assessing patients with cystic sellar and parasellar tumours.

Identification of Small Proteins and Peptides in the Differentiation of Patients with Intraductal Mucinous Neoplasms of the Pancreas, Chronic Pancreatitis and Pancreatic Adenocarcinoma

BACKGROUND

There are a limited number of studies investigating the type of serum proteins capable of differentiating intraductal papillary mucinous neoplasms from benign or malignant diseases of the pancreas.

AIMS

To select proteins able to differentiate intraductal papillary mucinous neoplasms from benign and malignant pancreatic disease using semiquantitative proteomics.

METHODS

Serum samples were obtained from 74 patients (19 with type II intraductal papillary mucinous neoplasms, 8 with type I/III intraductal papillary mucinous neoplasms, 24 with chronic pancreatitis, 23 with pancreatic ductal adenocarcinomas) and 21 healthy subjects. Small proteins and peptides were assayed by matrix-assisted laser desorption/ionization for the detection of differentially abundant species possibly related to tumor onset. Serum pancreatic amylase, lipase, carcinoembryonic antigen and carbohydrate antigen 19-9 (CA 19-9) were also assayed.

RESULTS

Twenty-six of 84 peaks detected were dysregulated (7 more abundant and 19 less abundant in the type II intraductal papillary mucinous neoplasms, p < 0.05). Of the differentially abundant peaks, 17 were commonly dysregulated (3 peaks more abundant and 13 less abundant in type II intraductal papillary mucinous neoplasms, and one at  m/z = 9961 at variance), indicating a protein fingerprint shared by types I/III and type II intraductal papillary mucinous neoplasms and pancreatic ductal adenocarcinomas.

CONCLUSIONS

These results suggest that our approach can be used to differentiate type II intraductal papillary mucinous neoplasms from type I/III neoplasms, and type II intraductal papillary mucinous neoplasms from pancreatic ductal adenocarcinomas.

Cystic Craniopharyngiomas: Microsurgical or Stereotactic Treatment?

BACKGROUND

Prognosis and treatment of cystic craniopharyngiomas are poorly defined.

OBJECTIVE

To analyze progression-free survival (PFS) and safety profile of cystic craniopharyngiomas undergoing resection or minimally invasive drainage procedures. We compared further outcome measurements for cystic and solid tumors undergoing resection to elucidate the impact of the initial tumor composition on both PFS and the toxicity profile.

METHODS

All patients with craniopharyngiomas consecutively treated between 1999 and 2014 were included. A treatment decision in favor of microsurgery or stereotactic treatment was made interdisciplinarily. For stereotactic drainage, a catheter was implanted, allowing both permanent upstream (into ventricular spaces) and downstream (into prepontine cistern) drainage. Study endpoints were tumor progression, functional outcome, and treatment toxicity. Functional endocrinological and visual outcome analyses referred to data obtained preoperatively and 6 weeks after treatment. The Kaplan-Meier method was used for survival analysis. Prognostic factors were obtained from proportional hazard models.

RESULTS

Seventy-nine patients were included. The distribution of clinical and tumor-related data was well balanced among patients with solid (n = 35) and cystic (n = 44) tumors and those undergoing microsurgical or stereotactic treatment. Cystic tumors had shorter PFS (5-year PFS: 53.6% vs 66.8%, P = .10) and needed significantly more therapeutic interventions, which was independent of the initial treatment mode. The endocrinological deterioration rate was high for both solid and cystic tumors after microsurgery (59.4% and 85.7%, respectively), whereas it was significantly lower for cystic tumors undergoing stereotactic treatment (23.1%, P < .001).

CONCLUSION

Stereotactic bidirectional drainage of cystic craniopharyngiomas is effective and provides a better endocrinological outcome than conventional microsurgery.

Mature Cystic Teratoma of Dorsal Spinal Cord in Adult: An Unusual Lesion

Teratomas are a type of multipotential cell tumor that contain a mixture of multiple germinal layers formed by normal organogenesis and reproductive tissues the incidence of intracranial teratomas is low, approximately 0.5-2.2% of all intracranial tumors. The occurrence of teratomas in the spine is extremely rare. Except for in the sacrococcygeal region, teratomas constitute <0.5% of all intraspinal tumors. According to the literature this is only 8^th case of dorsal spinal mature cystic teratoma reported till date.

Stereotactic Radiosurgery for Cystic Vestibular Schwannomas

BACKGROUND

The optimum treatment for cystic vestibular schwannoma (VS) remains controversial. Anecdotally, many treating physicians feel that cystic VSs do not respond to stereotactic radiosurgery (SRS) as well as noncystic tumors.

OBJECTIVE

To present outcomes after treatment of predominantly cystic VS with SRS.

METHODS

A prospectively maintained clinical database of patients undergoing Gamma Knife (Elekta Instruments, Stockholm, Sweden) radiosurgery (GKRS) for VS at a single tertiary academic referral center was retrospectively reviewed. Patients diagnosed with cystic VS who were treated with GKRS between 1997 and 2014 were analyzed. Size-matched solid tumors treated with GKRS during this period were selected as controls.

RESULTS

Twenty patients (12 women; median age at treatment, 56 years; range, 36-85 years) with cystic VS met inclusion criteria. The median radiologic follow-up within the cystic group was 63 months (range, 17-201 months), and the median change in tumor size was -4.9 mm (range, -10.4 to 9.3 mm). Sixteen tumors (80%) shrank, 2 (10%) remained stable, and 2 (10%) enlarged, accounting for a tumor control rate of 90%. The median radiologic follow-up in the noncystic control group was 67 months (range, 6-141 months), and the median change in size was -2.0 mm (range, -10.4 to 2.5 mm). Tumor control in the solid group was 90%. Comparing only those tumors that decreased in size showed that there was a trend toward a greater reduction within the cystic group ( P = .05).

CONCLUSION

The present study demonstrates that tumor control after SRS for cystic VS may not differ from that of noncystic VS in selected cases.

Cystic lymphangioma of the lesser omentum in a pregnant woman: a case report and review of the literature

Lymphangiomas are rare benign tumors which are generally seen in pediatric population and the etiopathogenesis has not yet been understood. They occasionally occur in the head and neck or axillary region with only 5% of them being located in the abdominal or mediastinal cavity. These tumors may be asymptomatic or may cause acute abdominal symptoms due to the location and extention. In the English literature, only 4 cases of lymphangioma were reported to have occurred in the pregnancy period. Herein, we report a case of cystic lymphangioma of the lesser omentum detected incidentally on the ultrasonogram of a 21 year-old, 26-week pregnant woman. The patient was followed up uneventfully during pregnancy. Caesarean section was performed due to transverse presentation of the fetus, and the tumor was completely resected during the same session. The patient is recurrence-free after 1 year of postoperative follow-up.

A rare case of giant multicystic solitary fibrous tumor of the orbit

Solitary fibrous tumor (SFT) is a rare spindle cell tumor of the orbit of mesenchymal origin. Though these tumors are mostly solid, partial or complete cystic changes can rarely occur. Only six such previous cases of cystic fibrous tumor of the orbit have been mentioned in the literature. We report a case of an elderly male who presented with a huge left sided medial orbital mass. Magnetic resonance imaging showed a predominant cystic orbital mass separated by septae and suggested a diagnosis of Hydatid cyst. The patient underwent complete excision of the mass and histopathology and immunohistochemistry were suggestive of cystic SFT. Cystic degeneration in SFT is extremely rare and can be a harbinger of malignancy, and pose risk of recurrence. Close follow up and monitoring is required for all such cases.

Endoscopic Management of Pancreatic Cysts

Management of pancreatic cystic lesions relies on patients' clinical presentation, imaging, and endoscopic ultrasound. Current research in basic science, radiology, and endoscopy is evolving and making progress in this condition which is relatively common in the general population. This review focuses on the recent endoscopic ultrasound approaches to the diagnosis of these pancreatic disorders.

A primary intraosseous cystic meningioma: Case report

INTRODUCTION

This is a very rare case of intraosseous cystic meningioma. There have been no reports of similar cases in the last 30 years.

PRESENTATION OF CASE

A 62-year-old man, suffering from a swelling of the lateral wall of the left orbit was admitted to our hospital. MRI and CT scan showed a large intradiploic lesion involving the lateral wall of the orbit and the greater wing of the sphenoid. The lesion was cystic with a mural nodule. We operated the patient and removed completely the mural nodule and the fibrous wall of cyst. Histological examination showed that the mural nodule was a benign meningothelial meningioma.

DISCUSSION

Primary intraosseous meningiomas represent a subtype of primary extradural meningiomas; they comprise about 2% of all meningiomas and are therefore rare entities. Cystic meningiomas are rare, their incidence compared to all other types of meningiomas is of 2-4%. The presence of a meningioma with both characteristics: cystic and intraosseous, like in our case, is an exceptional occurrence.

CONCLUSION

The surgical management of tumor was easy; its rarity means that the case is interesting.

Mesenteric Teratoma in Elderly Female: A Rare Case Report

Dermoid cysts rarely present as mesenteric cysts. Mesenteric cysts are rare pathologic entities, with a reported incidence of approximately 1 of 27 000 to 1 of 100 000 admissions. Mesenteric cyst was first described by Florentine anatomist Benevieni in 1507, while performing an autopsy on an eight-year-old boy. Most commonly, teratoma occurs in the early age group. Mature mesenteric teratoma in adulthood is extremely rare. Teratoma are germ cell tumours commonly composed of multiple cell types derived from one or more of the 3 germ layers. We present the case of a 69-year-old elderly female who presented with abdomen pain for nine months with right lumbar and right iliac fossa mass. Computed Tomography (CT) abdomen revealed bilocular cystic lesion with possibility of mucinous cystadenoma with no definitive organ of origin. She underwent explorative laparotomy and total excision of the cystic mass. Histopathologic examination confirmed diagnosis of mature cystic teratoma of mesentery. This case report highlights the need to maintain high index of suspicion while evaluating abdominal mass.

Solid-Cystic Hypoglossal Nerve Schwannoma with Fluid-Fluid Level: A Rare Case Report

Schwannomas (neurinoma, neurilemmoma) are benign slow-growing encapsulated tumours originating from well-differentiated myelin-producing Schwann cells or nerve fiber sheet cells at the glial-Schwann cell junction. Hypoglossal nerve schwannoma mostly develops in the intracranial and extra-cranial segment or in both intracranial and extra-cranial segment forming a dumbbell shape tumour. The peripheral hypoglossal schwannomas are very rare. We present a case of right hypoglossal nerve schwannoma in a 46-year-old female who presented with headache and neck pain since 2 weeks with deviation of tongue to right side since 1 week. Patient was investigated with Computed Tomography (CT) scan of head and Magnetic Resonance Imaging (MRI) of brain, which showed a dumb-bell shaped solid-cystic mass lesion with fluid-fluid level in right cerebello-pontine angle cistern.

Totally cystic intradural schwannoma in thoracic region

Spinal schwannomas are benign intradural extramedullary tumors arising from spinal nerve root sheath. They are usually solid or heterogeneously solid. Totally cystic schwannomas are rare entities. Herein, we report a 60-year-old male presenting with backache radiating along the chest wall and weakness of both lower limbs. He had spastic paraparesis. Magnetic resonance imaging revealed a cystic mass in the thoracic region. At operation, the cystic mass was seen to be attached to D4 dorsal rootlets. It was excised in toto and histopathology confirmed it to be a schwannoma. The relevant literature is reviewed.

Nodular Cystic Basal Cell Carcinoma of the Trunk: a Diagnostic Dilemma in an Unsuspecting Youth

Basal cell carcinoma (BCC) commonly affects the elderly and is mostly confined to the head and neck region. Only 10% of all cases occur on the trunk. We presented a case of bullous lesion on the abdomen in a young male, initially diagnosed by clinicians as a vascular nevus. Histopathological examination and immunohistochemistry (IHC) revealed it to be Nodular cystic variant of BCC. This rare variant of BCC morphologically resembles benign skin adnexal tumor of Eccrine syringofibroadenoma. Ber Ep4 positivity on IHC established the correct diagnosis. This case highlights that nodular cystic variant of BCC can be a diagnostic dilemma for clinicians and pathologists.

Multi-recurrent invasive ameloblastoma: A surgical challenge

Introduction

Ameloblastomas are rare head and neck tumors, and yet the most common odontogenic neoplasms. They account for 1% and 11% of all head and neck and odontogenic tumors respectively. Embryologically, they originate from remnants of odontogenic epithelium. Their aggressive, destructive nature, as well as their anticipated high rate of recurrence, even after en bloc resection, poses a surgical predicament.

Presentation

We present a case of a 56 year-old Asian female with a multi-recurrent invasive ameloblastoma. Initially, the lesion was mandibular in location for which she underwent a mandiblectomy. Later on, she presented with a maxillary ameloblastoma with invasion of both the anterior wall of the maxillary sinus and the floor of the orbit. The patient was operated twice and histopathology confirmed a cystic type recurrent ameloblastoma. A year later, she came with recurrent maxillary ameloblastoma and a maxillectomy was done. However, histopathology revealed a follicular ameloblastoma. Three years later, she presented with a retro-orbital ameloblastoma with infiltration to the temporal muscles. The patient was operated and the histopathologic examination revealed a partially cystic lesion with no malignant transformation.

Conclusion

This case discusses available treatment options and emphasizes on the importance of long-term patient follow-up due to the biological behavior of ameloblastoma.

Cystic and necrotic papillary renal cell carcinoma: prognosis, morphology, immunohistochemical, and molecular-genetic profile of 10 cases

Conflicting data have been published on the prognostic significance of tumor necrosis in papillary renal cell carcinoma (PRCC). Although the presence of necrosis is generally considered an adverse prognostic feature in PRCC, we report a cohort of 10 morphologically distinct cystic and extensively necrotic PRCC with favorable biological behavior. Ten cases of type 1 PRCC with a uniform morphologic pattern were selected from the 19 500 renal tumors, of which 1311 were PRCCs in our registry. We focused on precise morphologic diagnosis supported by immunohistochemical and molecular-genetic analysis. Patients included 8 men and 2 women with an age range of 32-85 years (mean, 62.6 years). Tumor size ranged from 6 to 14 cm (mean, 9.4 cm). Follow-up data were available in 7 patients, ranging from 0.5 to 14 years (mean, 4 years). All tumors were spherical, cystic, and circumscribed by a thick fibrous capsule, filled with hemorrhagic/necrotic contents. Limited viable neoplastic tissue was present only as a thin rim in the inner surface of the cyst wall, consistent with type 1 PRCC. All cases were positive for AMACR, OSCAR, CAM 5.2, HIF-2, and vimentin. Chromosome 7 and 17 polysomy was found in 5 of 9 analyzable cases, 2 cases demonstrated chromosome 7 and 17 disomy, and 1 case showed only chromosome 17 polysomy. Loss of chromosome Y was found in 5 cases, including 1 case with disomic chromosomes 7 and 17. No VHL gene abnormalities were found. Papillary renal cell carcinoma type 1 can present as a large hemorrhagic/necrotic unicystic lesion with a thick fibroleiomyomatous capsule. Most cases showed a chromosomal numerical aberration pattern characteristic of PRCC. All tumors followed a nonaggressive clinical course. Large liquefactive necrosis should not necessarily be considered an adverse prognostic feature, particularly in a subset of type 1 PRCC with unilocular cysts filled with necrotic/hemorrhagic material.

Cystic meningioma: radiological, histological, and surgical particularities in 43 patients

BACKGROUND

The presence of cysts is a rare occurrence for intracranial meningiomas in adults. We report our experience in a large consecutive series of cystic meningiomas.

METHOD

We prospectively collected data for a dedicated database of cystic meningioma cases between January 2004 and December 2011 in two tertiary neurosurgical centers. Studied data included preoperative imaging, surgical records, and pathology reports.

RESULTS

Among 1214 surgeries for intracranial meningioma, we identified 43 cases of cystic meningioma, corresponding to an incidence of 3.5 %. The most common localization was the hemispheric convexity (17/43 cases). Twenty-eight patients had intratumoral cysts, nine peritumoral, and five mixed intra and extratumoral. In 29 patients with available diffusion imaging, ADC coefficients were significantly lower in grade II-III tumors compared to grade I (p = 0.01). Complete resection of the cystic components was possible in 27/43 patients (63 %); partial resection in 4/43 (9 %); in 6/43 (14 %) cyst resection was not possible but multiple biopsies were performed from the cystic walls; in another 6/43 (14 %) the cystic wall was not identified during surgery. Cells with neoplastic features were identified within the cyst walls at pathology in 26/43 cases (60 %). All patients were followed-up for 24 months; long-term follow-up was available only in 32 patients for an average period of 49 months (range, 36-96 months). No recurrence requiring surgery was observed.

CONCLUSIONS

Cystic meningiomas are rare. Cells with neoplastic features are often identified within the cyst walls. Complete cyst resection is recommendable when considered technically feasible and safe.

Giant cystic pheochromocytoma: A silent entity

Pheochromocytoma is a catecholamine secreting tumor that originate from chromaffin cells. Usually, it is solid neoplasm of the adrenal medulla, however cystic pheochromocytoma is a rare neuro-endocrine tumour that is frequently asymptomatic and often diagnosed incidentally on imaging or intra-operatively. Only a few cases of cystic pheochromocytomas have been reported in the world literature. We present a case of giant cystic pheochromocytoma in a 65 years old lady who presented with a large retroperitoneal lump, which is probably the world's third largest pheochromocytoma as per the available indexed literature.

MR Imaging of Mediastinal Masses

The high soft tissue contrast of MR imaging enables superior tissue characterization of mediastinal masses, adding diagnostic specificity and often changing and benefiting clinical management. MR imaging can better discern cystic from solid content and can detect microscopic fat, hemorrhage, and fibrous content within lesions. In many cases, mediastinal MR imaging may prevent unnecessary diagnostic intervention. In other cases, MR imaging may indicate the optimal site for biopsy or the correct compartment for resection. Awareness of the efficacy of MR imaging with regard to mediastinal mass characterization and judicious MR imaging utilization should further improve patient care.