Extensive vertebral scalloping in a case of giant cystic spinal schwannoma: more than just a radiological diagnosis.

To the Editor,A 44 year old female presented to us with complains ofnew onset lower extremity weakness and numbnessinvolving bilateral lower extremities. She had prior his-tory of T12- S1 laminectomy and resection of intraduralschwannoma about 15 years back and external beamradiation treatment for recurrence of the tumor 10 yearsago. She sustained weakness due to the tumor but hasbeen ambulatory with some sensory deﬁcits. Magneticresonance imaging (MRI) of the spine at last follow updemonstrated residual tumor which had been treatedexpectantly over the past few years in light of no newneurological deﬁcits. Physical exam demonstrated weak-ness in the lower extremities, with new onset proximalweakness on baseline distal weakness and decreasedreﬂexes and sensation throughout with difﬁculty inambulation. Contrast MRI of the lumbar spine revealed alarge heterogeneously enhancing solid cystic mass com-pletely ﬁlling the lumbar spinal canal centered on L2–L4leading to severe scalloping of the posterior cortex of L3and L4 vertebral bodies and extension into the neuralforamen and erosion of pedicles at multiple levels.Computed tomography (CT) was performed to assess thebony anatomy and plan the surgical strategy consideringsigniﬁcant evidence of bone destruction on the MRIwhich clearly demonstrated extensive vertebral scallopingleading to almost completely destruction of the L3 ver-tebral body secondary to scalloping with erosion ofbilateral pedicles at multiple levels (Fig. 1). She wasinitially treated with steroids with subtle improvement.Considering the newer deﬁcits with interval enlargementof the tumor, surgical resection was offered with resec-tion of the tumor and multilevel instrumentation andreconstruction of the spine as there was erosion of thevertebral bodies and pedicles precluding simple recon-struction. Understanding the risk involved, the patientelected to pursue non operative care and was transferredto a rehabilitation facility.Schwannomas are benign encapsulated tumors thatoriginate from myelinated peripheral and cranial nervesheaths [1, 2]. While spinal schwannoma can undergohemorrhage, calciﬁcation, and ﬁbrosis; cystic changes inspinal schwannoma is uncommon [1]. MRI is the pre-ferred imaging modality of choice to delineate theoverall pathology [1]. One of the features on radiologyquite typical of these tumors is the posterior vertebralscalloping sign deﬁned as an exaggeration of normalconcavity of posterior surface of vertebral bodies [3]. Itis commonly caused by increased intraspinal pressuresecondary to an expanding mass and often a sign of along standing benign slow growing lesion such as aspinal schwannoma or other intradural tumors [3]. Duralectasia, small spinal canal, congenial skeletal disordersand soft tissue hypertrophy are the various pathogeneticmechanisms implicated in the development of vertebralscalloping [3]. Though often a common radiologicalﬁnding indicating a benign nature of the disease, severevertebral scalloping as depicted in the presented case canhave severe clinical consequences and has not beendescribed earlier. The present case highlights themalignant nature of severe vertebral scalloping leading toalmost complete vertebral destruction involving the L3vertebral body and erosion of the bilateral pediclesinvolving multiple levels. The presence of these vertebral