Hyun Wook Lim

Pilomatricomas in children: imaging characteristics with pathologic correlation

BackgroundAlthough pilomatricoma commonly occurs in children, there is still a poor understanding of the imaging characteristics of pilomatricoma and lack of agreement regarding its imaging findings and histopathologic features.ObjectivesTo characterize the radiologic appearance of pilomatricomas on US, CT, and MR and to correlate the imaging findings with histopathologic features.Materials and methodsThe imaging findings of 47 pilomatricomas on US (n = 17), CT (n = 31), and MR (n = 5) were retrospectively evaluated. Pathologic specimens of all cases were reviewed and compared with imaging findings.ResultsAll lesions were well-circumscribed, subcutaneous nodules with partial attachment to the overlying skin. On US, the lesions were mostly hyperechoic with posterior acoustic shadowing and hypoechoic rim. On CT, they appeared as enhancing soft-tissue masses with varying amounts of calcification. MR findings were internal reticulations and patchy areas on T2-weighted images and contrast-enhanced T1-weighted images, corresponding to edematous stroma on pathology. Peritumoral inflammatory changes and connective capsule on pathology were well correlated with imaging findings.ConclusionPilomatricoma should be considered when US or CT shows a well-defined hyperechoic or calcific nodule in subcutaneous fat attached to the skin in children. MR images may be helpful in diagnosis. Pathologic findings are well correlated with imaging findings.

Ultrasonographic Findings of Medullary Thyroid Carcinoma: a Comparison with Papillary Thyroid Carcinoma

Objective This study was designed to evaluate the ultrasonographic (US) findings of medullary thyroid carcinoma (MTC) as compared to findings for papillary thyroid carcinoma (PTC). Materials and Methods The study included 21 cases of MTC that were surgically diagnosed between 2002 and 2007 and 114 cases of PTC that were diagnosed in 2007. Two radiologists reached a consensus in the evaluation of the US findings. The US findings were classified as recommended by the Thyroid Study Group of the Korean Society of Neuroradiology and Head and Neck Radiology (KSNHNR) and each nodule was identified as suspicious malignant, indeterminate or probably benign. The findings of medullary and papillary carcinomas were compared with use of the chi-squared test. Results The common US findings for MTCs were solid internal content (91%), an ovoid to round shape (57%), marked hypoechogenicity (52%) and calcifications (52%). Among the 21 cases of MTC nodules, 17 (81%) were classified as suspicious malignant nodules. The mean size (longest diameter) of MTC nodules was 19 ± 13.9 mm and the mean size (longest diameter) of PTC nodules was 11 ± 7.4 mm; this difference was statistically significant (p < 0.05). An ovoid to round shape was more prevalent for MTC lesions than for PTC lesions (p < 0.05). Conclusion The US criteria for suspicious malignant nodules as recommended by the Thyroid Study Group of the KSNHNR correspond to most MTC cases. The US findings for MTC are not greatly different from PTC except for the prevalence of an ovoid to round shape.

Emphasis on the MR imaging findings of brown tumor: a report of five cases

ObjectiveBrown tumors are focal reactive osteolytic lesions that are encountered in patients with primary or secondary hyperparathyroidism, and these tumors have nonspecific magnetic resonance (MR) imaging findings. However, there are only a few reports on MR imaging of brown tumors. The purpose of this study is to describe the spectrum of MR imaging findings of brown tumors.Materials and methodsThe MR imaging features of five patients with clinical and pathological evidence of brown tumor were retrospectively reviewed by two radiologists. The patients had primary hyperparathyroidism, which was confirmed as parathyroid adenoma (n = 2) and parathyroid carcinoma (n = 3). The MR images were evaluated for the presence of solid or cystic portions, the signal intensity of the lesions, the contrast enhancement pattern and the presence of cortex destruction and fluid-fluid levels.ResultsTwelve bone lesions were detected on the MR images of five patients; three lesions in two patients, four lesions in one patient, and one lesion in two patients. The tumor was solid in three lesions, mixed solid and cystic in four, and cystic in five. All the solid lesions were accompanied by mixed lesions. Discontinuity of the cortex and adjacent soft-tissue enhancement were seen in all the solid lesions. Fluid-fluid levels were seen in two cases within the cystic component of the mixed lesions and cystic lesions.ConclusionsThe five patients with brown tumor demonstrated a wide spectrum of MR imaging findings. There are few lesions that are osteolytic on the radiographs and that show a short T2 on MR imaging, such as brown tumor. Multiple cystic or mixed lesions are the expected findings of brown tumors.

Polyvinyl alcohol embolization adjuvant to oily chemoembolization in advanced hepatocellular carcinoma with arterioportal shunts.

Objective To assess the feasibility and safety of polyvinyl alcohol (PVA) embolization adjuvant to transarterial oily chemoembolization (P-TACE) in advanced hepatocellular carcinoma (HCC) with arterioportal shunts (APS). Materials and Methods Nineteen patients who underwent PVA embolization for APS before a routine chemoembolization (TACE) procedure were retrospectively reviewed. 10 of these 19 patients underwent follow-up TACE or P-TACE after P-TACE (Group A), but nine patients underwent only initial P-TACE because of progression of HCC and/or underlying liver cirrhosis (Group B). Hepatic function tests, APS grades, and portal flow directions were evaluated before and after P-TACE sessions. Complications after procedures and survival days were also evaluated. Results In group A, APS grade was improved in eight patients and five of six patients with hepatofugal flow showed restored hepatopetal flow postoperatively. No immediate complication was developed in either group. Transient hepatic insufficiency developed in eight (42.1%) of 19 patients after P-TACE, and seven (87.5%) of these eight recovered within two weeks under conservative care. The mean and median survival time all study subjects was 280 days and 162 days. Conclusion P-TACE is feasible and safe in advanced HCC patients with APS.

Giant cell tumor with secondary aneurysmal bone cyst: A unique presentation with an ossified extraosseous soft tissue mass

The authors describe a case of giant cell tumor (GCT) with secondary aneurysmal bone cyst (ABC) in a 44-year-old man with chronic, intermittent knee pain. A unique feature is the presentation of GCT with an ossified extraosseous soft tissue mass. Radiograph demonstrates a multiloculated lytic lesion in the distal meta-epiphyseal region of the femur with an adjacent extraosseous soft tissue mass. The soft tissue mass was partially ossified along its margin and internal septa. MRI demonstrates a multiloculated lesion in the distal femur with multiple fluid–fluid levels and cortical penetration of the lesion. Both the intraosseous lesion and extraosseous soft tissue mass have similar MR signal characteristics. At surgery, the intraosseous component was found to be contiguous with the extraosseous soft tissue mass through a cortical perforation. To the best of our knowledge, this is the first case report of GCT with aneurysmal bone cyst initially presenting with an extraosseous soft tissue mass.

Diagnostic accuracy of 64-slice multidetector CT angiography for detection of in-stent restenosis of vertebral artery ostium stents: comparison with conventional angiography.

Background There are very few reports assessing in-stent restenosis (ISR) after vertebral artery ostium (VAO) stents using multidetector computed tomography (MDCT). Purpose To compare the diagnostic accuracy of computed tomography angiography (CTA) using 64-slice MDCT with digital subtraction angiography (DSA) for detection of significant ISR after VAO stenting. Material and Methods The study evaluated 57 VAO stents in 57 patients (39 men, 18 women; mean age 64 years [range, 48–90 years]). All stents were scanned with a 64-slice MDCT scanner. Three sets of images were reconstructed with three different convolution kernels. Two observers who were blinded to the results of DSA assessed the diagnostic accuracy of CTA for detecting significant ISR (≥50% diameter narrowing) of VAO stents in comparison with DSA as the reference standard. The sensitivity, specificity, positive and negative predictive values, and accuracy were calculated. Results Of the 57 stents, 46 (81%) were assessable using CTA, while 11 (19%) were not. No stents with diameters ≤2.75 mm were assessable. DSA revealed 13 cases of significant ISR in all stents. The respective sensitivity, specificity, positive and negative predictive values, and accuracy were 92%, 82%, 60%, 97%, and 84% for all stents. On excluding the 11 non-assessable stents, the respective values were 88%, 95%, 78%, 97%, and 93%. Of the 46 CTA assessable stents, eight significant ISRs were diagnosed on DSA. Seven of eight patients with significant ISR by DSA were diagnosed correctly with CTA. The area under the receiver-operating characteristic curve (AUC) was 0.87 for all stents and 0.91 for assessable stents, indicating good to excellent agreement between CTA and DSA for detecting significant ISR after VAO stenting. Conclusion Sixty-four-slice MDCT is a promising non-invasive method of assessing stent patency and can exclude significant ISR with high diagnostic values after VAO stenting.