Role of ultrasonography in detection of renal artery pseudoaneurysm caused by retroperitoneal malignant peripheral nerve sheath tumor in a patient with neurofibromatosis type 1.

Malignant peripheral nerve sheath tumors (MPNSTs) are extremely uncommon neoplasms, predominantly seen within the deep soft tissues of the extremities, in close proximity to the nerve trunks. Retroperitoneal MPNSTs are exceedingly rare, usually seen in association with neurofibromatosis type 1 (NF-1), and often result from malignant degeneration of a plexiform neurofibroma. These tumors are highly malignant and the prognosis is worsened if they occur in association with NF-1. Metastasis is not uncommon, but local invasion by these tumors is rarely reported. Renal artery pseudoaneurysms are mostly iatrogenic and rarely result from invasion by retroperitoneal neoplasms. Ultrasonography is a valuable tool in early diagnosis of these neoplasms and vascular complications, particularly in emergency cases requiring immediate operative intervention. To the best of our knowledge, no case of renal artery pseudoaneurysm caused by retroperitoneal MPNST has been reported to date. We present a case of a middle-aged female with Von Recklinghausen disease, complaining of sudden onset of severe abdominal pain, where ultrasound accurately diagnosed renal artery pseudoaneurysm caused by a large retroperitoneal MPNST, and who was later treated by radical excision of the tumor and nephrectomy.