Neurosurgical Management of a Painful Subcutaneous Nodule of the Knee

Abstract

Abstract BACKGROUND AND IMPORTANCE: Angioleiomyoma (ALM) is a rare, benign smooth muscle tumor that can occur anywhere in the body. Diagnosis is usually delayed due to the unfamiliar location and presentation of the lesion. This tumor is not frequently discussed in neurosurgical publications as part of the differential diagnosis of painful subcutaneous lesions. To our knowledge, this is the first report of a neurosurgical presentation of ALM within an extremity. CLINICAL PRESENTATION: A 42-year-old woman presented with more than 2 years of severe right knee pain. The patient had undergone several treatments, including a knee arthroscopy, all without significant relief. Magnetic resonance imaging performed with a fiducial marker placed directly on the point of tenderness demonstrated an 8-mm subcutaneous nodule. The patient underwent complete excision of the lesion, guided by the placement of the fiducial marker and its correlation with the preoperative magnetic resonance imaging. Intraoperatively, the lesion was not found to be associated with a nerve; however, there was a small vessel adjacent to the lesion. Pathology demonstrated this lesion to be an ALM. The patient's symptoms had completely resolved without any new neurological parasthesias or deficits on follow-up. CONCLUSION: Neurosurgeons should keep ALM in the differential diagnosis of painful extremity lesions. Localization using a fiducial marker directly overlying the area of suspicion is useful for the neurosurgeon and also for the radiologist so that the lesion may not be overlooked. Unnecessary interventions for the patient may be avoided with appropriate diagnosis, and surgical resection provides complete cure of the symptoms.