Subcutaneous granuloma annulare: MR imaging findings

We present a case of subcutaneous granuloma annulare evaluated with MR imaging. The mass was poorly defined and showed thickened interconnecting strands with low signal intensity on T1- and T2-weighted MR images. When a poorly defined subcutaneous mass with low signal intensity on both T1- and T2-weighted MR images is observed in an otherwise healthy child, subcutaneous granuloma annulare should receive serious consideration. Subcutaneous granuloma annulare should be added to the list of tumors with short T2.     

Complex renal cysts: findings on MR imaging.

OBJECTIVE: We retrospectively evaluated our experience with complex cystic renal masses on MR imaging, using T1-weighted, T2-weighted, and gadolinium-enhanced images, to determine whether imaging features could permit distinction between benign and malignant lesions. MATERIALS AND METHODS: Thirty-seven patients with complex cystic renal lesions were included in this retrospective study. The patients selected had undergone T1-weighted, T2-weighted, and gadolinium-enhanced MR imaging examinations using 1.5-T scanners, with at least one of the following findings: cyst fluid of heterogeneous signal intensity, mural irregularity, septa, mural masses or nodules, increased mural thickness, or intense mural enhancement. The diagnosis was established by histology in 19 patients and by follow-up studies in the remaining 18 patients. RESULTS: Fifty-five complex renal cystic lesions were present in the 37 patients. Among the 55 lesions, of 37 that contained fluid of a heterogeneous signal intensity, eight were malignant (22%); of 16 with irregular walls, 10 were malignant (63%); of four with septa, two were malignant (50%); of four with mural masses or nodules, three were malignant (75%); of 14 with a thick wall (>2 mm), 10 were malignant (71%); and of 32 with intense mural enhancement, 14 were malignant (44%). As independent variables, mural irregularity, mural masses or nodules, increased mural thickness, and intense mural enhancement each were highly associated with malignancy (p = .0003-.0022). The combination of mural irregularity and intense mural enhancement had the highest correlation with malignancy (p = .0002). CONCLUSION: The combination of mural irregularity and intense mural enhancement is a strong predictor of malignancy in renal cystic lesions. However, the appearance of benign and malignant lesions may overlap, suggesting that distinct separation of these entities is not currently possible in all cases with MR imaging.     

Human papillomavirus-associated plantar epidermoid cysts: MR and US imaging appearance

Epidermoid cysts are epithelial cysts that present as slow-growing intradermal or subcutaneous lesions. While recent epidemiological studies have isolated human papillomavirus (HPV) from plantar epidermoid cysts, imaging findings in HPV-associated epidermoid cysts have not been previously reported. We describe imaging findings in two patients with HPV-associated plantar epidermoid cysts. Magnetic resonance (MR) imaging and ultrasonography (US) showed linear arrangement of several adjacent globular cysts. This appearance is hypothesized to result from HPV-associated eccrine duct metaplasia leading to cyst formation and later traumatic rupture leading to formation of multiple adjacent cystic components. It may be useful to suggest assessing the presence of HPV antigen in plantar lesions having these imaging findings.     

Sonographic and MR imaging findings of testicular epidermoid cysts

OBJECTIVE: The purpose of this study is to analyze the sonographic and MR imaging findings of testicular epidermoid cysts. CONCLUSION: Sonographic findings of a markedly heterogeneous intratesticular mass with or without alternating hypo- and hyperechoic layers surrounded by a hypoechoic or echogenic rim and the absence of flow on color Doppler sonography suggest the preoperative diagnosis of testicular epidermoid cysts. T2-weighted MR imaging findings of a high-signal-intensity mass with or without low-signal-intensity foci surrounded by a low-signal-intensity rim and the absence of enhancement on contrast-enhanced T1-weighted MR images can strengthen the preoperative diagnosis. These imaging findings can offer a basis for surgeons to attempt testis-sparing surgery instead of orchiectomy.     

Testicular cysts: US findings

Testicular cysts have been considered rare. However, of 307 men who underwent high-resolution ultrasonography (10 MHz) of the scrotum, 30 (9.8%) had testicular cysts. Thirty-three testes were involved, 23 with single cysts, eight with clusters of multiple tiny cysts, and two with more than one focus of cyst. One cyst was aspirated intraoperatively, and one cyst of the tunica albuginea was proved at surgery. Eighty cadaveric testes were scanned also, and cysts were found in one. In two cases, the pathologic report, reviewed retrospectively, failed to mention the cyst, but these cysts could have been overlooked. Further work is needed to determine when or if these testicular lesions need follow-up and what significance they have, if any.     

Pineal cysts: MR imaging

MR brain scans of 672 consecutive patients were examined prospectively to determine the incidence of high-signal pineal glands on T2-weighted images. The scans were obtained on either a 0.15-T or 0.5-T unit. This finding was present in 29 patients, none of whom had hydrocephalus or symptoms of a pineal mass. A CT scan was available in 17 of these cases and none of these demonstrated a solid pineal mass. Because of the frequency of this observation (4.3%) and the absence of associated findings, it was concluded that benign pineal cysts are the most likely explanation for this high signal. It is important for the radiologist to consider benign cysts in the differential diagnosis of a bright pineal gland on T2-weighted MR images.     

MR imaging findings of Rathke's cleft cysts: significance of intracystic nodules

BACKGROUND AND PURPOSE: Rathke's cleft cysts often may be difficult to differentiate from other intrasellar or suprasellar masses on radiologic studies. The purpose of this study was to describe the significance of intracystic nodules, a diagnostic characteristic found in Rathke's cleft cysts, on MR images. METHODS: A retrospective review of MR studies was conducted for 13 patients who, after pathologic analysis, were diagnosed as having Rathke's cleft cyst. These patients underwent unenhanced and contrast-enhanced T1- and T2-weighted axial and coronal spin-echo sequential imaging. The signal intensity and incidence of the intracystic nodules on T1- and T2-weighted images were analyzed. The signal intensity of the nodule was compared with that of white matter and surrounding cyst fluid. The signal intensity of cyst fluid was compared with the intraoperative appearance of the cyst fluid. Biochemical and pathologic analyses of the intracystic nodules were conducted in two cases. RESULTS: An intracystic nodule having high signal intensity on T1-weighted images and low signal intensity on T2-weighted images was observed in 10 (77%) of the cases. At surgery, intracystic nodules were yellow, waxy, solid masses. Pathologic analysis showed this nodule to be a mucin clump. Biochemical analysis of the intracystic nodules showed cholesterol and proteins as the main constituents. In the Rathke's cleft cyst with intracystic nodules, cyst fluid revealed low signal intensity to isointensity relative to the intensity of the nodules on T1-weighted images, and isointensity to high signal intensity on T2-weighted images. Intracystic nodules were clearly visible on T2-weighted images. CONCLUSION: Because cyst fluid of Rathke's cleft cysts shows variable intensities on MR images, the specific diagnosis is often difficult when based on MR signal intensity values alone. The presence of an intracystic nodule with characteristic signal intensities on MR images may be indicative of the diagnosis of Rathke's cleft cyst.     

Primary hyperaldosteronism (Conn syndrome): MR imaging findings

PURPOSE: To describe the magnetic resonance (MR) imaging features of the adrenal glands in primary hyperaldosteronism and assess MR imaging in the detection and characterization of aldosterone-producing adenoma (APA). MATERIALS AND METHODS: The authors retrospectively reviewed the cases of 20 patients (13 female and seven male patients; age range, 14-67 years; median age, 46 years) with primary hyperaldosteronism who underwent 1.5-T MR imaging between 1995 and 1998. All patients underwent transverse T1- and T2-weighted imaging, and chemical shift imaging was performed in 17 patients. Imaging results were correlated with findings at biochemical testing, venous sampling, or surgery. RESULTS: Among the 20 patients, 10 (50%) had APA and 10 (50%) bilateral adrenal hyperplasia (BAH). In the detection of APA, MR imaging had a sensitivity of 70%, specificity of 100%, and accuracy of 85%. APAs (mean size, 20 x 16 mm) were iso- or hypointense relative to the liver on T1-weighted images and slightly hyperintense on T2-weighted images. With chemical shift imaging, the signal intensity decreased on the out-of-phase images in six of seven (86%) patients with APA and in eight of nine (89%) patients with BAH. CONCLUSION: MR imaging has a high specificity in the detection of APA. As with nonhyperfunctioning adenoma, APA and BAH show evidence of intracellular lipid at chemical shift imaging.     

Glioependymal cysts: CT and MR findings.

Four patients with intracranial glioependymal cysts were evaluated in our institution in the last 7 years. All underwent surgical drainage and biopsy of the cyst wall. Cranial CT revealed a uniformly hypodense lesion with no contrast enhancement in all cases. Magnetic resonance imaging studies revealed a well defined cyst that was isointense to CSF on T1-weighted images and iso- or mildly hyperintense to CSF on proton density and T2-weighted images. In one case, a fluid-fluid level was demonstrated within the cavity, indicating the presence of fluid with a high protein content. A diagnosis of glioependymal cysts can be suggested based on CSF-like intensity patterns on T1-weighted images and iso- or mild hyperintensity on T2-weighted images.     

Multiple intracranial hydatid cysts: MR findings

Multiple intracranial hydatid cysts are uncommon and usually localized in the supratentorial compartment. We report a case studied by CT and MR of multiple intracranial hydatid cysts scattered in various anatomic sites: supratentorial, infratentorial and also intraventricular. Correspondence to: J. M. Pumar Cebreiro     

Intraspinal synovial cysts: MR imaging

Juxtaarticular intraspinal synovial cysts are unusual lesions of the spine associated with facet arthropathy. These lesions can cause radicular symptoms and may masquerade clinically as other, more common entities. Synovial cysts have been detected at myelography and have been well characterized at computed tomography as posterolateral epidural masses, typically at L4-5. Six synovial cysts of the lumbar spine were demonstrated on magnetic resonance (MR) images. The signal-intensity patterns of these lesions are variable. MR imaging can be used to document the presence of hemorrhage within the cyst, which may relate to the exacerbation of symptoms. Air-filled synovial cysts may be difficult to detect and distinguish from facet arthropathy.     

Sacroiliitis: MR imaging findings

Magnetic resonance (MR) imaging was performed in seven asymptomatic volunteers and 17 patients with clinical and radiologic evidence of sacroiliitis. MR imaging findings were compared with those at computed tomography (CT) to determine the MR imaging appearance of the sacroiliac joint when normal and in sacroiliitis. The normal articulation was well depicted with MR imaging. Findings of sacroiliitis were identified in 20 sacroiliac joints (12 patients). MR imaging findings characteristic of sacroiliitis included abnormal cartilage signal intensity (95% of joints) and erosions (75% of joints) on T1-weighted images. Areas of increased intensity in the articulation (80% of joints) or in erosions (60% of joints) were seen on T2-weighted images. MR imaging was superior to CT for evaluation of cartilage and detection of erosions. Four sacroiliac joints (20%) and two patients (17%) with MR imaging findings of sacroiliitis were negative at CT. The authors conclude that MR imaging is a valuable method for detecting sacroiliitis, particularly when results of other imaging techniques are inconclusive.     

Subcutaneous granuloma annulare: MR imaging and literature review

Subcutaneous granuloma annulare (SGA) is little known to radiologists. Better knowledge of this lesion may prompt accurate diagnosis. A typical case is presented with plain radiography, ultrasound and MR imaging, and is confirmed by histology. When an otherwise healthy child presents with a rapidly growing, solitary, nontender, subcutaneous soft tissue mass, located on the scalp or extensor aspect of the limbs, that radiologically presents as an indistinct radiodense and hypoechoic mass, isointense to muscle on T1- and slightly hypointense to fat on T2-weighted MR images, without calcifications, bone involvement or extracompartmental invasion, SGA should be suspected. Received 5 June 1997; Revision received 29 October 1997; Accepted 8 January 1998     

Bilateral microphthalmos with orbital cysts: MR findings

We present magnetic resonance features of a case of bilateral microphthalmos with orbital cysts, a rare congenital anomaly resulting from defects in closure of the embryonic fissure of the optic disk.