H. R. Harnsberger

Intralabyrinthine Schwannomas: Imaging Diagnosis and Classification

BACKGROUND AND PURPOSE: ILS is a rare lesion that has a different management from the more common “acoustic” schwannoma. To date, only 137 cases have been reported. We present a classification scheme based on labyrinthine anatomy to describe and localize these lesions. Treatment and prognosis hinge on the appropriate localization of these tumors; thus, a concise terminology that can be used by both the otolaryngologist and radiology communities is desirable. MATERIALS AND METHODS: After approval of the institutional review board, a retrospective study of all patients with the diagnosis of ILS imaged between 1996 and 2010 was performed. Clinical and imaging data were collected. Patients were imaged with thin-section high-resolution T2 and contrast-enhanced MR imaging. RESULTS: There were 45 patients with a diagnosis of ILS. Forty-three had complete histories. There were 18 male and 25 female patients with an age range of 21–78 years with a mean age of 53 years. The most common presenting symptom was progressive sensorineural hearing loss. Lesions were characterized on the basis of their location. Intracochlear was most common (14/45) followed by transmodiolar (13/45), intravestibular (7/45), vestibulocochlear (5/45), transmacular (4/45), and transotic (2/45). Sixteen patients underwent surgical resection. The remaining patients were followed clinically and by serial MR imaging. CONCLUSIONS: ILS is an uncommon but under-reported tumor. We characterized the MR imaging appearance of these tumors by using high-resolution techniques. In addition, an anatomically based classification system is presented that will help the radiologist accurately describe ILS within the inner ear and help the surgeon determine which tumors are potential surgical candidates.

Craniopharyngeal Canal and Its Spectrum of Pathology

BACKGROUND AND PURPOSE: The craniopharyngeal canal is a rare, well-corticated defect through the midline of the sphenoid bone from the sellar floor to the anterosuperior nasopharyngeal roof. We reviewed a series of craniopharyngeal canals to determine a system of classification that might better our understanding of this entity, highlight the range of associated pathologic conditions, and optimize patient treatment. MATERIALS AND METHODS: Available MR imaging, CT, and clinical data (from 1989–2013) of 29 patients (10 female, 15 male, 4 unknown; median age, 4 years; age range, 1 day–65 years) with craniopharyngeal canals were retrospectively examined. Qualitative assessment included orthotopic or ectopic adenohypophysis and the presence of a tumor and/or cephalocele. The midpoint anteroposterior diameter was measured. Clinical and imaging data were evaluated for pituitary dysfunction and accompanying anomalies. RESULTS: Craniopharyngeal canals were qualitatively separated into 3 types: incidental canals (type 1); canals with ectopic adenohypophysis (type 2); and canals containing cephaloceles (type 3A), tumors (type 3B), or both (type 3C), including pituitary adenoma, craniopharyngioma, dermoid, teratoma, and glioma. Quantitative evaluation showed a significant difference (P < .0001) in the anteroposterior diameters of type 1 canals (median, 0.8; range, 0.7–1.1 mm), type 2 canals (median, 3.9, range, 3.5–4.4 mm), and type 3 canals (median, 9.0; range, 5.9–31.0 mm) imparting small, medium, and large descriptors. Canals with cephaloceles all contained an ectopic adenohypophysis. The craniopharyngeal canals were associated with pituitary dysfunction (6/29) and congenital anomalies (8/29). CONCLUSIONS: Accurate diagnosis and classification of craniopharyngeal canals are valuable to characterize lesions requiring surgery, identify patients with potential pituitary dysfunction, and avoid iatrogenic hypopituitarism or CSF leak during surgical resection of nasopharyngeal masses.

Carotid Body Detection on CT Angiography

BACKGROUND AND PURPOSE: Advances in multidetector CT provide exquisite detail with improved delineation of the normal anatomic structures in the head and neck. The carotid body is 1 structure that is now routinely depicted with this new imaging technique. An understanding of the size range of the normal carotid body will allow the radiologist to distinguish patients with prominent normal carotid bodies from those who have a small carotid body paraganglioma. MATERIALS AND METHODS: We performed a retrospective analysis of 180 CTAs to assess the imaging appearance of the normal carotid body in its expected anatomic location. RESULTS: The carotid body was detected in >80% of carotid bifurcations. The normal size range measured from 1.1 to 3.9 mm ± 2 SDs, which is consistent with the reported values from anatomic dissections. CONCLUSIONS: An ovoid avidly enhancing structure at the inferomedial aspect of the carotid bifurcation within the above range should be considered a normal carotid body. When the carotid body measures >6 mm, a small carotid body paraganglioma should be suspected and further evaluated.

Imaging characteristics of primary laryngeal lymphoma.

BACKGROUND AND PURPOSE: The larynx is a rare site for primary NHL. Fewer than 100 cases have been reported in the literature, with the largest imaging review involving only 4 patients. We describe the findings of laryngeal lymphoma on CT, PET, and MR imaging and identify features that may distinguish laryngeal lymphoma from the far more common laryngeal squamous cell carcinoma. MATERIALS AND METHODS: Multi-institutional retrospective chart review revealed 20 patients with histopathologically proved laryngeal lymphoma. Pretreatment CT, PET, and MR images were reviewed by a head and neck radiologist, focusing on extent of tumor, cervical lymph node involvement, and enhancement patterns. RESULTS: Patients ranged from 30 to 90 years of age with a mean of 63 years at the time of initial diagnosis and a 2:1 female predominance. The average tumor size was 37 ± 19 mm. In all patients, laryngeal lymphoma involved the supraglottis but also extended into the glottis (65%) and hypopharynx (60%). The subglottis was less frequently involved (35%). Laryngeal cartilage invasion and cervical lymphadenopathy were each seen in 20% of patients. Lymphoma was consistently FDG-avid (100%) and usually enhanced uniformly with iodinated contrast (73%). Necrosis and calcification were not seen in any cases. CONCLUSIONS: Although laryngeal lymphoma is rare, particular imaging features suggest this diagnosis. A large uniformly enhancing supraglottic tumor without central necrosis and without cervical lymphadenopathy is a characteristic finding of lymphoma. Similar to squamous cell carcinoma, lymphoma may extend into the subglottis, pharynx, and laryngeal cartilages.

Giant arachnoid granulations just like CSF?: NOT!!

SUMMARY: “Giant” AGs (>1 cm) are uncommon and can be misdiagnosed as venous sinus pathology such as a neoplasm or thrombosis. Seventeen patients with a total of 19 venous sinus AGs of >1 cm were collected from contributing authors. MR imaging was available for all AGs; CT, for 5/19; and DSA, for 7/19. Intra-AG fluid was compared with CSF in subarachnoid spaces. Nonfluid AG tissue was compared with gray matter. Diagnosis was based on imaging findings. Fluid within giant AGs did not follow CSF signal intensity on at least 1 MR image in nearly 80% (15/19) of AGs. Nine of these 15 AGs had CSF-incongruent signal intensity on ≥2 MR images. CSF-incongruent signal intensity was seen in 8/8 AGs on FLAIR, 7/10 on precontrast T1WI, 13/19 on T2WI, and 8/14 on contrast-enhanced T1WI. Nonfluid signal intensity was present in 18/19 AGs and varied from absent/hypointense (intra-AG flow voids) to gray matter isointense (stromal tissue).

Extraosseous Chordoma of the Nasopharynx

BACKGROUND AND PURPOSE: Chordoma is a relatively rare tumor of the skull base and sacrum thought to originate from embryonic remnants of the notochord. Chordomas arising from the skull base/clivus are typically locally aggressive with lytic bone destruction. When chordomas occur in an extraosseous location, they may mimic other lesions of the nasopharynx. We present 5 cases of primarily extraosseous chordoma involving the nasopharynx in an effort to improve the preoperative diagnosis of this rare tumor. In addition, we review regional notochordal embryology to explain this variant tumor location. MATERIALS AND METHODS: We reviewed the clinical and imaging data of 5 pathologically proved cases of extraosseous chordoma of the nasopharynx seen or reviewed at our institution during the last decade. All cases had both CT and MR imaging. The study had institutional review board approval. RESULTS: The primary clinical complaint in the 5 patients with extraosseous nasopharyngeal chordoma was nasal obstruction. The extraosseous chordomas were centered in the nasopharynx. Bony lytic changes along the anterior surface of the clivus were seen on 5 of 5 CT studies. A midline sinus tract was seen in 3 of 5 patients. MR imaging showed heterogeneous hyperintense T2 signal intensity (5/5). CONCLUSIONS: Extraosseous nasopharyngeal chordoma is a rare but important lesion to be considered in the differential diagnosis of nasopharyngeal masses. When a midline nasopharyngeal mass is found with an associated clival sinus tract, extraosseous chordoma moves to the top of the differential diagnosis list. Complete removal of the soft-tissue tumor and the clival sinus tract is the treatment of choice in such cases.

Sinonasal polyposis: investigation by direct coronal CT.

To demonstrate the typical clinical and CT features of sinonasal polyposis, we reviewed the clinical records and preoperativ direct coronal CT scans of 35 patients with surgically proven disease. Symptoms included progressive nasal stuffiness (100%), rhinorrhea (69%), facial pain (60%), headache (43%) and anosmia (17%). We found associations with rhinitis (46%), asthma (29%) and aspirin sensitivity (9%). Coronal CT features included polypoid masses in the nasal cavity (91%), partial or complete pansinus opacification (90%), enlargement of infundibula (89%), bony attenuation of the ethmoid trabeculae (63%) and nasal septum (37%), opacified ethmoid sinuses with convex lateral walls (51%) and air-fluid levels (43%). The latter feature correlated with symptoms and signs of acute sinusitis in only 40% of patients. Recognition of sinonasal polyposis is important to the endoscopic surgeon since it can be the most troubling sinonasal inflammatory disease to manage due to its aggressive nature and tendency to recur despite appropriate treatment.

Spontaneous Lateral Sphenoid Cephaloceles: Anatomic Factors Contributing to Pathogenesis and Proposed Classification

Imaging findings in 26 patients with spontaneous lateral sphenoid cephaloceles were studied. The authors were able to classify these lesions into those involving the lateral recess of the sphenoid sinus that typically manifested as CSF leaks and headaches, and a second type that involved the lateral sphenoidal wing without extension into the sinus and presented with a variety of findings including seizures, headaches, meningitis, or neuropathy, or were incidental. All patients showed sphenoid arachnoid pits and 61% had an empty or partially empty sella. SUMMARY: Spontaneous lateral sphenoid cephaloceles arise from bony defects in the lateral sphenoid, in the absence of predisposing factors such as trauma, surgery, mass, or congenital skull base malformation. We reviewed CT and MR imaging findings and clinical data of 26 patients with spontaneous lateral sphenoid cephaloceles to better understand anatomic contributions to pathogenesis, varying clinical and imaging manifestations, and descriptive terminology. Two types of spontaneous lateral sphenoid cephaloceles were identified. In 15 of 26 patients, a type 1 spontaneous lateral sphenoid cephalocele was noted, herniating into a pneumatized lateral recess of the sphenoid sinus, and typically presenting with CSF leak and/or headache. In 11 of 26 patients, a type 2 spontaneous lateral sphenoid cephalocele was noted, isolated to the greater sphenoid wing without extension into the sphenoid sinus, presenting with seizures, headaches, meningitis, cranial neuropathy, or detected incidentally. All patients had sphenoid arachnoid pits, and 61% of patients had an empty or partially empty sella, suggesting that altered CSF dynamics may play a role in their genesis.

CT and MRI of the normal and diseased perivertebral space

The perivertebral space is in the midline, in the deep tissues of the neck, and can be identified from the skull base above to the mediastinum below. It is a discrete space completely enclosed by the deep layer of deep cervical fascia. The fascial attachments of the perivertebral space divide it into two areas, the anteriorprevertebral and posteriorparaspinal portions. We made a retrospective analysis of the radiologic and clinical records of 52 patients with lesions in the perivertebral space, to identify the imaging features that mark a lesion as originating in the perivertebral space and define the spectrum of pathology which occurs in the space. Mass lesions present in the prevertebral or paraspinal portions. In the former they usually involve the vertebral body, displacing the prevertebral muscles anteriorly. Epidural extension from lesions in the perivertebral space proper is common. Masses in the paraspinal perivertebral space usually displace the paraspinal muscles away from the spine. We found 9 inflammatory lesions, 29 malignant and 6 benign tumors, and 8 miscellaneous lesions.

Oncocytoma: the vanishing parotid mass.

This is a small retrospective study of a rare lesion, so why include it here? The report describes a previously unknown imaging feature of parotid gland oncocytomas, which appears to be specific for these tumors. All were hypointense with respect to the surrounding gland on precontrast T1 images, but became invisible on postcontrast fat-suppressed T1- and T2-weighted sequences (thus the title of the article). The illustrations are convincing but because this is a retrospective analysis, I wonder how many oncocytomas will show this imaging behavior. SUMMARY: Parotid gland oncocytoma is an uncommon, benign salivary neoplasm composed of mitochondria-rich oncocytes. The purpose of this study was to correlate MR imaging and histopathology of parotid gland oncocytomas and to define the features that may distinguish these neoplasms from other benign and malignant parotid gland tumors. The MR imaging features in 9 patients with a pathologic diagnosis of oncocytoma were retrospectively reviewed. The imaging features were strikingly similar for 8 of the 9 patients. All lesions appeared T1 hypointense but isointense to the native parotid gland on fat-saturated T2 and postcontrast T1 imaging. On MR imaging, parotid gland oncocytomas share specific imaging characteristics that have not been described for benign or malignant parotid gland tumors. Oncocytomas are isointense to native parotid gland on fat-saturated T2 and T1 postcontrast MR images. Preoperative identification of correct histology may help surgical planning.