Clival Incidentaloma

CASE HISTORY

A 62-year-old male had experienced atypical dysuria and penile pain for 6 months. He had already seen a urologist and a neurologist. The urological and neurological evaluations had not identified the cause of his pain. He felt well and had no other complaints. His medical history was remarkable only for kidney stones for which he had undergone lithotripsy. The patient's physical and neurological examinations were completely normal. Magnetic resonance imaging (MRI) of the thoracic and lumbar spine, obtained previously, was also normal.

Computed tomography (CT) of the head showed a well-defined focus of bone erosion in the clivus slightly to the right of midline and opening into the midline through the posterior clivus. MRI of the brain showed a nonenhancing, sharply demarcated mass located in the midclivus, extending toward the prepontine cistern (Fig. [1]). The mass was hypointense on T1-weighted images and hyperintense on T2-weighted images.

Figure 1 (A) Axial CT (bone window) shows a focus of bone loss in the clivus that opens toward the pons. (B) Sagittal noncontrast T1-weighted MRI shows a well-circumscribed nodule in the clivus. (C) The mass, which is bright on this axial T2-weighted MRI, appears to extend into the subarachnoid space.

ACTUAL MANAGEMENT The patient underwent a left retrosigmoid craniotomy for resection of the tumor. Intraoperative MRI-based image guidance (Stealth, Medtronic) was used. The cerebellopontine angle was accessed. The tumor was exposed by working between the vestibulocochlear and cranial nerve IX, X, XI complex. The mass was grayish-white with a stalk extending from the clivus. It was firm and partially calcified. The mass was completely resected and a margin of adjacent tissue and bone was removed. Final pathological examination revealed a modestly cellular mass with clusters and strands of cells with myxoid stroma, which tested positive for keratin AE1/AE3 and S-100, consistent with a diagnosis of chordoma. Postoperatively, the patient complained of bilaterally decreased hearing, which resolved by the time he returned to the office for suture removal. The patient was discharged to home on postoperative Day 6. Early follow-up MRI showed no residual mass. The patient was referred for gamma knife radiosurgery to the tumor bed.

REFERENCES

• 1 Currarino G. Canalis basilaris medianus and related defects of the basiocciput.  AJNR Am J Neuroradiol. 1988;  9 208-211
• 2 Martinez C R, Hemphill J M, Hodges III F J et al.. Basioccipital meningocele.  AJNR Am J Neuroradiol. 1981;  2 100-102