Salivary gland tumors: evaluation with two-phase helical CT

Distinguishing benign from malignant parotid gland tumours: low-dose multi-phasic CT protocol with 5-minute delay

Objectives

To explore the percentage enhancement wash-out ratio (PEW) and relative PEW (RPEW) of low-dose multi-phasic computed tomography (CT) in distinguishing benign from malignant parotid gland tumours.

Methods

This study was approved by the ethics committee, and informed patient consent was obtained. 51 patients with parotid tumours proven by histopathology received CT, including 18 with pleomorphic adenomas, 14 with Warthin’s tumours and 19 with malignant tumours. Size and attenuation of parotid tumours were measured. Compared with 5-min attenuation, the 30-s and 90-s PEW (PEW_30, PEW₉₀) and RPEW (RPEW₃₀, RPEW₉₀) were calculated.

Results

There was a significant difference in PEW₃₀, RPEW₃₀, PEW₉₀ and RPEW₉₀ in the parotid neoplasms groups (P < 0.01), and statistical significance existed simultaneously in pleomorphic adenomas vs malignant tumours and Warthin’s tumours vs malignant tumours according to SNK-q test. The optimal diagnosis results of malignancy with 100% specificity (32/32) was obtained by using a combination of the following criteria: −70% > PEW₃₀ < 36%, −30% > PEW₃₀ < 19%, PEW₉₀ > 12%, and the sensitivity (74%) for diagnosis of malignancy was yield.

Conclusions

Wash-out ratio may assist in differentiating the benign from malignant parotid gland tumours. Combining the percentage of enhanced wash-out ratios of CT protocols can yield diagnostic results for malignancy.

CT features of parotid gland oncocytomas: a study of 10 cases and literature review

Oncocytomas of the salivary glands are rare benign epithelial tumors which occur most commonly in the parotid gland. The aim of our study was to characterize the clinical-radiologic-pathologic spectrum of parotid oncocytomas in a series of 10 cases seen in our institution between January 2003 and November 2008. The CT features of parotid oncocytomas in the largest imaging series of this rare but important benign lesion include a well-defined enhancing tumor with a "deformable" appearance when large, and a non-enhancing curvilinear cleft or cystic component. These CT findings are potentially helpful in distinguishing these benign lesions from other parotid tumors in clinical scenarios that preclude surgical resection or when biopsy results are non-diagnostic. Further studies are advocated to validate the specificity and positive predictive value of these imaging features.

Myopericytoma involving the parotid gland as depicted on multidetector CT

Myopericytoma is a newly proposed subgroup of perivascular tumors in the World Health Organization classification of soft tissue tumors. In this study, we report a case of a benign myopericytoma with detailed multidetector CT (MDCT) findings in the parotid gland, a location that has not been described for this type of tumor previously. The clinical presentation, imaging features, histopathological and immunohistochemical findings, and the differential diagnosis with other tumors in the parotid gland are described and reviewed.

Pleomorphic adenoma of parotid gland: delayed enhancement on computed tomography

OBJECTIVES

To assess the efficacy of multiphasic CT with 8 min delayed acquisition in the differential diagnosis between pleomorphic adenomas and other parotid neoplasias.

METHODS

Between January 2004 and April 2007, 62 patients with parotid enlargement were enrolled in this prospective study. The CT protocol applied included the following four acquisitions: without contrast medium and 30 s, 120 s and 8 min after intravenous injection of contrast medium. We considered the degree of the enhancement of the lesions (rated as "low", "moderate" and "strong") and the degree of enhancement homogeneity (rated as "not homogeneous", "mildly homogeneous" and "uniform"). These parameters were compared with Hounsfield values of the lesions computed in each phase. The diagnosis was confirmed in all patients after surgery.

RESULTS

On histological examination, 36 tumours were classified as pleomorphic adenomas and 26 as non-pleomorphic adenomas. On the basis of a statistical comparison, the third phase proved to be the most effective in the differential diagnosis between pleomorphic adenoma and non-pleomorphic adenomas, both for the assessment of the degree of the enhancement (in this phase, strong enhancement showed a sensitivity of 61.11%, specificity of 100%, positive predictive value (PPV) of 100% and negative predictive value (NPV) of 53.33%) and, above all, for the homogeneity of the enhancement (in this phase, indeed, uniform enhancement showed sensitivity, specificity, PPV and NPV of 100%).

CONCLUSIONS

Our results seem to indicate that multiphasic CT with 8 min delayed acquisition allows the differential diagnosis between pleomorphic adenomas and other parotid neoplasias.

Myoepithelioma of the parotid gland: CT imaging findings

BACKGROUND AND PURPOSE

Myoepitheliomas (MEs) are rare tumors of the parotid gland. Only a few case reports describing CT imaging features of ME have been published. The aim of this study was to describe and characterize the CT findings of MEs of the parotid gland.

MATERIALS AND METHODS

We retrospectively reviewed CT images of ME with pathologic correlation in 10 cases (4 men and 6 women; age range, 30-70 years) collected between August 2003 and October 2007 from our pathologic database. All of the CT images were retrospectively evaluated with respect to the location, size, marginal morphology, enhancement, and enhancement pattern by 2 experienced radiologists.

RESULTS

Nine tumors were located in the superficial lobe of the parotid gland, and 1 was located in the tail of parotid gland. All of the tumors abut on the capsule of the gland. Nine tumors had well-defined margins with lobulations in 5 patients. Two cases showed homogenous enhancement. In the other 8 cases, the enhancement was inhomogeneous because of enhancing nodules and nonenhancing areas of linear bands, slitlike-shaped or of cystic configuration.

CONCLUSION

CT imaging findings of MEs were well circumscribed, enhancing the mass lesion with smooth or lobulated margins, located chiefly in the superficial lobe and abutted on the capsule of the gland. They may contain enhancing nodules and nonenhancing areas of linear bands, slitlike-shaped or of cystic configuration. Although MEs are a rarity, they should be suspected when a tumor shows all of the characteristics noted here.

Solitary fibrous tumor of the orbit: CT and MR imaging findings

BACKGROUND AND PURPOSE

Solitary fibrous tumor (SFT) is a rare spindle-cell neoplasm originating from mesenchymal fibroblast-like cells. The purpose of this study was to describe the CT and MR imaging features of SFTs in the orbit.

MATERIALS AND METHODS

We retrospectively reviewed CT and MR images in 6 patients (2 men and 4 women), aged 18 to 51 years, with SFT proved on histologic examination located in and around the orbit. All patients underwent CT (including dual-phase CT in 3), and MR imaging was obtained in 3. We evaluated the imaging findings with emphasis on the location, size, margin, internal architecture, and pattern of enhancement of the lesion.

RESULTS

All 6 lesions were found as a solitary, well-defined mass, ranging in size from 18 to 30 mm (mean, 24 mm). Three were located in the postseptal orbit, 2 in the lacrimal sac, and 1 on the lower eyelid. Compared with the cerebral cortex, all 3 lesions examined by MR imaging showed homogeneous isointense signal intensity on T1-weighted images and heterogeneous mixed isointense and hyperintense signal intensity on T2-weighted images. On visual inspection, all 6 lesions showed marked homogeneous (n = 4) or heterogeneous (n = 2) enhancement on postcontrast CT and MR images. In 3 patients examined with dual-phase CT, all lesions demonstrated rapid enhancement with early washout of contrast material.

CONCLUSION

SFT might be included in the differential diagnosis of soft tissue masses in the orbit, if one sees a markedly enhancing mass showing the similar characteristics to those of the internal carotid artery on postcontrast CT or MR images.

Myoepitheliomas of the soft palate: helical CT findings in two patients

We describe the enhancement patterns of myoepithelioma in two patients with a soft palate mass. In the first case, helical CT revealed a faintly enhancing mass. Histologically, the tumor was composed of plasmacytoid cells in a background of rich myxoid stroma. Immunostaining for CD34 showed scanty blood vessels. In the second case, helical CT revealed an intensely enhancing mass. Histologically, the mass was a cellular tumor with fibrous stroma. Immunostaining for CD34 also showed frequent blood vessels.

Epithelial-myoepithelial carcinoma of the parotid gland, unusual malignancy radiologically simulating a benign lesion: case report

Background

Ultrasound (US), Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) are widely used in the clinical diagnosis of parotid gland tumors and their efficacy in identifying benign lesions is well documented. However, problems arise when facing some malignant lesions. Only few cases of salivary gland low grade malignant tumors have been previously reported in the literature complete with the radiological features.

Case presentation

We here describe a case of epithelial-myoepithelial carcinoma (EMC) of the parotid gland, a low grade malignant tumor, with spread to an intraparotid lymph node and with CT and MRI findings mimicking a benign lesion.

Conclusion

All the images revealed sharply outlined profiles and a homogeneous enhancement of the nodule, suggesting a benign tumor and demonstrating that a radiological evaluation of the lesion alone may be unsatisfactory and misleading in the diagnosis of salivary gland tumours, especially in the case of low grade malignant tumors, such as EMC.

Dynamic multislice computed tomography findings for parotid gland tumors

OBJECTIVE

Our aim was to research the enhancement features of parotid gland masses in detail and characterize if the masses were Warthin tumors, adenomas, or malignant tumors.

METHODS

The prospective study included 25 parotid tumors in 21 patients. Neck computed tomography (CT) was performed using a multislice CT unit. A full-neck CT examination was done at 30 seconds after completion of contrast injection, and then tumor-level images were obtained at 90 seconds and at 5 and 25 minutes. Computed tomography number (lesion density in Hounsfield units) was determined at each phase, and differences within and among tumor groups were statistically analyzed. Diagnoses were confirmed by histopathology.

RESULTS

There were 11 Warthin tumors, 8 pleomorphic adenomas, 5 malignant tumors, and 1 basal cell adenoma. Ten Warthin tumors showed rapid contrast enhancement at 30 seconds and rapid reduction of enhancement from the first to the fourth phase. The basal cell adenoma showed also a peak enhancement at 30 seconds. Seven pleomorphic adenomas showed increased enhancement through the first 3 phases. Four malignant tumors showed peak enhancement at 90 seconds. Statistically significant differences within and among tumor groups were determined.

CONCLUSIONS

The data suggest that peak tumor enhancement at 30 and 90 seconds, respectively, might identify Warthin and malignant tumors. Increased enhancement through all phases might be an indicator for diagnosing pleomorphic adenomas.

Basal cell adenomas of the parotid gland: CT scan features

Basal cell adenoma (BCA) is a rare tumor of the parotid gland, and except for a few case reports, the imaging features of this pathological entity are not well described. We describe the computed tomography (CT) features of 14 cases of histologically proven BCA, the largest series to date. In all cases, the tumor appeared as a round or oval, sharply marginated mass. Three cases showed homogenous enhancement. In the other 11 cases, the enhancement was inhomogeneous, due to either cystic areas, linear bands or stellate-shaped areas of non-enhancement. The latter two patterns have not been previously described in BCA or other parotid tumors, and may therefore aid in distinguishing BCA from other benign parotid neoplasms on CT.

Basal Cell Adenoma of the Parotid Gland

OBJECTIVE

The goal of this study was to report the radiologic characteristics of basal cell adenoma of the parotid gland, which is a relatively rare neoplasm.

METHODS

A radiology and otolaryngology specialist reviewed the 2-phase helical computed tomography (CT) (n = 6) and/or magnetic resonance (MR) imaging (n = 2) scans of 7 patients with basal cell adenoma. The authors evaluated the imaging characteristics, including tumor size, location, contour and margin, internal density or signal intensity, contrast enhancement pattern, and presence of calcification. The imaging features were then analyzed and correlated with the pathologic findings.

RESULTS

All the tumors presented as small (less than 3 cm), well-encapsulated, round or oval masses on CT or MR imaging. On the 2-phase CT scan, the mostly solid-looking tumors (n = 4) showed marked contrast enhancement on the early phase, and there was a subsequent decrease in attenuation on the delayed phase. These tumors were classified as the solid subtype on histologic examination. Meanwhile, the tumors with large cystic areas (n = 2) showed gradual and additional enhancement on the delayed phase and were classified as the tubular or trabecular subtype on pathologic evaluation. There were small spots of low attenuation in the tumors of the solid subtype, which were proved to be intratumoral microcysts in the pathologic correlation. Calcification was found in a tumor.

CONCLUSIONS

Basal cell adenomas of the parotid gland present as small well-marginated tumors and appear as masses with central large cysts or solid masses with microcysts on CT and MR imaging scans. Basal cell adenomas of the parotid gland had at least 2 different enhancement patterns on the 2-phase helical CT scans, and the enhancement patterns and imaging architecture were related to the histologic subtype of the tumors.

Basal cell adenoma of the parotid gland: dynamic CT and MRI findings

Imaging findings in basal cell adenoma (BCA) of the parotid gland have been rarely reported. We report dynamic CT and MRI findings of BCA in the parotid gland in a 78-year-old woman. Dynamic CT study demonstrated strong multinodular contrast enhancement in the early phase which decreased gradually in the later phases. The mass was isointense on T(1) weighted and hyperintense on T(2) weighted MR images with a central haemorrhagic-necrotic component. The microscopic findings were consistent with membranous type BCA.

Interpretation of the origin of a submandibular mass by CT and MRI imaging

OBJECTIVE

To clarify the useful findings for determining whether the submandibular mass is intraglandular or extraglandular.

STUDY DESIGN

Forty-eight patients with swelling of the submandibular region were reviewed. The relationship between the lesion and the submandibular gland and the displacement of the anterior facial vein were analyzed.

RESULTS

The accuracy of the predictions based on the relationship between the lesion and the submandibular gland (SMG) was 87% on contrast-enhanced CT (CECT), 85% on CT sialography (CTS), and 91% on MRI. Although the displacement of the facial vein outside the lesion suggested an intraglandular lesion, and inside the lesion suggested an extraglandular lesion, these were not sufficient to differentiate the lesions in 7 out of 23 CECT cases and 4 out of 11 MRI cases.

CONCLUSION

The finding of a relationship between the lesion and the SMG is the most important finding of this study.

Characteristic sonographic findings of Warthin's tumor in the parotid gland

PURPOSE

The aim of this study was to define the characteristic sonographic features of Warthin's tumors in the parotid gland, thus enhancing the ability to make a preoperative diagnosis of this disease process.

METHODS

We retrospectively evaluated the sonograms of Warthin's tumors of the parotid gland that had been confirmed by histopathologic examination of surgically excised specimens from patients treated at our institution over a 2-year period. We recorded the echogenicity, shape, margin, and internal structure of the tumors and categorized them into 2 groups on the basis of size (< 5 cm versus > or =5 cm in the largest diameter).

RESULTS

Eighteen patients (16 men and 2 women) with a mean age of 57 years (range, 29-82 years) were included in the analysis. One patient had 2 tumors (1 in each parotid gland); the other 17 patients each had only 1 tumor. Our review of the sonographic findings revealed that all 19 tumors were hypoechoic compared with the normal parenchyma of the affected parotid glands. Most of the tumors were ovoid, had well-defined margins, and contained multiple irregular, small, sponge-like anechoic areas. Tumors that were 5 cm or greater in diameter had a higher proportion of cystic content than smaller lesions had and in some cases were composed almost entirely of cystic material.

CONCLUSIONS

Our evidence suggests that the sonographic appearance of a Warthin's tumor in the parotid gland is distinctive: a well-defined round or ovoid hypoechoic mass containing microcystic anechoic areas. These sonographic features constitute useful criteria in the preoperative diagnosis of Warthin's tumor in the parotid gland, although sonographically guided fine-needle aspiration biopsy may be needed to confirm the diagnosis.

Orbital lymphoma and subacute or chronic inflammatory pseudotumor: differentiation with two-phase helical computed tomography

OBJECTIVE

The differentiation between orbital lymphoma and subacute or chronic inflammatory pseudotumor (SCIPT) may be difficult clinically and radiologically. The aim of this study was to evaluate the enhancement characteristics of orbital lymphoma and SCIPT with two-phase helical computed tomography (CT) and delayed coronal CT and to determine whether attenuation measurements on CT can be used to differentiate between the 2 diseases.

METHODS

Nineteen histopathologically proven orbital lymphomas and 9 SCIPTs were examined with two-phase helical CT. After injecting 90 mL contrast material at a rate of 3 mL/s, early- and late-phase axial CT scans were obtained with scanning delays of 30 and 90 seconds, respectively. Delayed coronal scans were obtained with delays of 4-9 minutes. Attenuation of the lesions at each phase was measured quantitatively. Relative percentages of contrast enhancement (CE) were calculated to determine the cutoff value for differentiating SCIPT from lymphoma.

RESULTS

The CT attenuation change over time was significantly different between orbital lymphoma and SCIPT (P < 0.05). Increased CT attenuation between early- and late-phase axial scans was seen in 42% (n = 8) of lymphoma cases, and decreased CT attenuation was seen in 58% (n = 11). In 17 lymphomas (90%), the CT attenuation decreased between late-phase axial and delayed coronal scans. Conversely, in 7 SCIPTs (78%), the CT attenuation increased gradually over time from early-phase axial to delayed coronal scans. The relative percentage of CE at the delayed coronal scan had a cutoff value of -6.97%, a sensitivity of 84%, and a specificity of 100%.

CONCLUSION

Different characteristics of attenuation change on two-phase helical CT and delayed coronal CT can be helpful in differentiating between orbital lymphoma and SCIPT.