Nerve Sheath Myxoma in the Lower Extremity: A Rare Case with Description of Magnetic Resonance Imaging and Sonographic Findings.

BACKGROUND This report is of a nerve sheath myxoma presenting as a slow-growing mass in the back of the left ankle of a 36-year-old man that was investigated by ultrasound and magnetic resonance imaging (MRI) before the diagnosis was confirmed by histopathology. CASE REPORT We report a nerve sheath myxoma of the ankle in a 36-year-old man. The palpable abnormality was falsely assumed to be a ganglion cyst prior to advanced imaging. Magnetic resonance imaging demonstrated a lobular mass with high T2 and intermediate T1 signal as well as moderate enhancement. T2 sequences also demonstrated distinctive internal septae. These internal septae were also noted on sonographic evaluation prior to biopsy. The patient was treated with surgical excision, and pathologic analysis showed myxoid nodules with loose arrangements of spindled cells separated by fibrous septae. S-100 protein and glial fibrillary acidic protein positivity by immunohistochemistry staining was demonstrated. Follow-up imaging at 12 months showed no evidence of tumor recurrence. CONCLUSIONS This case highlights that while nerve sheath myxomas are rare tumors, they should be considered in cases of cutaneous soft-tissue masses with myxoid imaging features. Ultrasound and magnetic resonance imaging features of thin internal septae may be present and correspond well with the unique histopathological characteristics of these lesions. This report shows the importance of imaging of peripheral soft-tissue masses, including ultrasound and MRI, which can identify localized and benign features and the solid, cystic, and myxoid areas, which were characteristic in this case of benign nerve sheath myxoma.

Teaching Neuroimages: a pediatric patient with headache and neck stiffness.

A 14-year-old right-handed boy presented with sudden onset of severe headache and neck stiffness. Physical examination showed arm asymmetry with smaller size and muscle bulk (present since childhood) and increased deep tendon reflexes on the right, but normal strength. Brain CT and lumbar puncture ruled out subarachnoid hemorrhage or infection. MRI and angiography (figure) identified an unruptured type III spinal arteriovenous malformation at the C3-C4 level, supplied by the right vertebral artery.(1) Subtle physical examination findings can indicate underlying pathology and should not be overlooked in the proper context. Vascular studies should be considered for severe headache with negative initial workup.(2.)

Experimental and theoretical investigation of the scope of enantioselective ketone allylations employing Nakamura's allylzinc-bisoxazoline reagent.

The scope of enantioselective allylations employing Nakamura's allylzinc-bisoxazoline reagent was examined by performing allylations of a selection of readily available ketones. Low-to-moderate ee's were observed, and a computational study was conducted to rationalize the results. Examination of transition structures of previously performed allylations that proceeded with high ee revealed the importance of both local and global control elements in these successful reactions. The ability of density functional theory methods to estimate the enantioselectivity of these asymmetric ketone allylations was established. All allylations that were studied computationally exhibited low (<5 kcal/mol) activation barriers, a result that is consistent with the highly reactive nature of Nakamura's reagent.