Temporal bone chondroblastoma totally invisible on MRI

Area of Science:

• Neuroimaging
• Oncology
• Otorhinolaryngology

Background:

• Chondroblastomas are rare, typically benign cartilage tumors, most common in the epiphyses of long bones.
• Temporal bone chondroblastomas are exceptionally rare, posing diagnostic difficulties due to their location and potential for subtle presentation.

Observation:

• A 64-year-old male presented with vertigo, and CT revealed a destructive lesion in the temporal bone involving the temporomandibular joint, middle cranial fossa floor, and superior semicircular canal.
• Calcific foci were noted on CT. However, the tumor was isointense/hypointense on T1 and T2 weighted MRI sequences and showed no contrast enhancement, rendering it "invisible" on all MRI sequences.
• The tumor's complete signal void on MRI, despite CT evidence of destruction and calcification, highlights a unique imaging characteristic.

Findings:

• Computed tomography (CT) successfully identified a destructive temporal bone lesion with calcifications.
• Magnetic resonance imaging (MRI) failed to detect the chondroblastoma, showing a complete signal void across all sequences (T1, T2, pre- and post-contrast).
• The chondroblastoma was surgically resected via a transpetrosal-transzygomatic approach.

Implications:

• This case underscores the critical role of CT in diagnosing temporal bone lesions when MRI may be inconclusive due to "invisible" tumors.
• It highlights the importance of considering chondroblastoma in the differential diagnosis of destructive temporal bone lesions, even with atypical imaging findings.
• The successful resection demonstrates the feasibility of surgical management for such challenging cases using advanced surgical approaches.