Fibromyxoma of the lateral skull base in a child: case report

Abstract

Purpose Fibromyxomas and myxomas are benign tumors of mesenchymal origin usually found outside the nervous system, most commonly in the atrium of the heart. They can also arise in the mandible or maxilla, but it is exceedingly rare to find them within the skull base. The history, histologic features, and the literature, with emphasis on other pediatric cases, are reviewed for this uncommon skull base neoplasm. Methods We describe the case of a 13-year-old girl who presented with a 1-year history of facial weakness, numbness, and hearing loss. A large locally destructive tumor centered in the petrous bone was found on magnetic resonance imaging. Results A mastoidectomy combined with a middle fossa craniotomy was performed for gross total resection. The child is disease free 12 months after surgery. Conclusion Diagnosis could not be made solely on radiographic studies because of the lack of pathognomonic imaging features. Radical resection provided the patient the best chance of cure. Long-term surveillance is necessary to monitor for tumor recurrence.

Keywords: benign; child; fibromyxoma; mesenchymal; myxoma; pediatric; petrous; skull base; tumor.

Fig. 1

(A) Axial T2-weighted magnetic resonance imaging through the skull base shows an expansile T2 hyperintense mass centered in the right petrous apex with linear internal hypointense septations. (B) Sagittal T1-weighted imaging shows that the mass involved the clivus and was predominantly T1 hypointense. (C) Axial T1-weighted image taken after gadolinium administration shows central areas of enhancement of internal septations. (D) Diffusion-weighted imaging shows no evidence of diffusion restriction.

Fig. 2

(A) Axial bone algorithm computed tomography (CT) showing the intraosseous lesion was expansile and resulted in cortical thinning but without discrete erosion. (B) Fusion image combining CT (orange) with axial T2-weighted image shows sparing of the otic capsule and ossicles.

Fig. 3

Histopathologic specimen showing fibromyxoma (hematoxylin and eosin). Note the alternating dense fibroconnective tissue and relatively hypocellular foci with myxoid matrix and spindle cells.

Fig. 4

(A) Axial T1-weighted magnetic resonance (MR) image shows hyperintense signal in the resection cavity corresponding to fat packing. (B) Axial T1-weighted postgadolinium MR image using fat suppression shows no evidence of solid enhancing tissue within the resection cavity.