Cellular myxoma of the lumbar spine
Here, we report a 57-year-old Caucasian female, with an unremarkable past medical history, who was referred to our neurosurgical department after she presented with an incidentally found lesion on magnetic resonance imaging (MRI) of her lower spine. On physical examination the patient did complain about discomfort in her pelvic area when sitting, left greater than right. However, she did not have any related neurologic complains such as back pain or leg pain, nor did she display any weakness, numbness or tingling sensation or other signs of radiculopathy. The mass was incidentally discovered on lumbar MRI, which was obtained for evaluation of her atypical pelvic pain.\nRoutine MRI was obtained demonstrating a right-sided sharply demarcated, poorly and heterogeneously contrast enhancing paraspinal lesion at the junction of the lumbar and sacral spine. The mass was localized immediately adjacent to the posterior elements (lamina and spinous process) and was deeply seeded in the right multifidus muscle adjacent to the L5 inferior articular process. It measured approximately 3.0 × 3.0 × 3.5 cm in size on T1 postcontrast images \n[]. Based on radiographic criteria alone, the differential diagnosis included: Schwannoma, lipoma or liposarcoma, fibroma, myoma, sarcoma or metastatic disease among rare other entities. A full systemic work up was performed and included a contrast enhanced computed tomography (CT) of the chest, abdomen, and pelvis as well as a mammogram and were negative for any other focus of systemic disease. As the lesion was concerning for a neoplasm, the patient was counseled and advised to pursue a histopathological diagnosis to direct further treatment options. She opted for an open surgical approach aiming for an excisional biopsy and she was consented and taken electively to surgery.\nPreoperative repeat MRI was performed within a 4 week window after initial presentation and revealed an unchanged right-sided paraspinal lesion at the level of the lower posterior lumbosacral spine. The lesion measured again approximately 3.5 cm in diameter and remained heterogeneously contrast enhancing and appeared somewhat lobulated. It continued to display sharp demarcation to the surrounding soft tissue. It did not show signs of erosion or invasion of the osseous parts of the L5 posterior elements.\nSurgery was performed under general anesthesia. The patient was positioned prone on a Wilson frame and a standard midline incision was performed after application of local anesthesia. The subcutaneous layers were split and the thoracolumbar fascia was divided. Dissecting into the soft tissue, we immediately identified a well encapsulated lesion deep in the paraspinal muscles, but the mass was adherent to the periostium of L5 and S1. An unremarkable dissection was performed and the lesion was resected in toto with a small soft tissue margin. Intraoperative fresh frozen analysis revealed a myxoid spindle cell tumor without significant atypia. Since the mass was abutting the osseous posterior elements of L5 and S1, we carefully coagulated the surface of the entire bony area that had been contacted to diminish the chances for any local recurrence. The wound was closed in layers and the patient had an unremarkable postoperative course. She was discharged to home the second postoperative day.\nThe entire specimen with a small clean margin was received for pathological examination and measured ca. 5 cm. Cut surfaces revealed a thinly encapsulated, well-circumscribed lesion with a soft white, gelatinous appearing cut surface. The specimen was entirely submitted for histopathological examination. Routine hematoxylin and eosin stains were performed on formalin-fixed, paraffin-embedded sections and showed a relatively well-circumscribed tumor composed of prominent myxoid stroma with a distinct presence of stellate-shaped bland cells with pyknotic nuclei and virtual absence of blood vessels []. In approximately 20% of the tumor specimen, areas of increased cellularity and vascularity were noted []. However, no mitotic activity, necrosis, or increase in nuclear atypia was noted in these foci. The tumor cells stained negatively for S100, actin, desmin, EMA, and cytokeratin cocktail. Based on the histopathological and immunophenotypical profile, a diagnosis of cellular myxoma was made.\nAs recurrence is very uncommon for such tumors after complete excision, no other therapeutic intervention was recommended. Due to the rather rare diagnosis of cellular myxoma in this locale – with overall dearth of evidence-based clinical recommendations – a close and frequent follow-up surveillance imaging schedule was established for this patient in spite of this entity being described as a benign tumor. To date, 42 months after the surgery, the patient remains neurologically intact, feels well and no recurrence has been observed on sequential imaging [Figure ].