Calvarium and dura mater as delayed sites of distant metastasis from papillary thyroid carcinoma

Abstract

Khalid Hussain AL-Qahtani,1 Mutahir A Tunio,2 Mushabbab Al Asiri,3 Hanadi Fatani,4 Yasser Bayoumi5 1Department of Otolaryngology-Head and Neck Surgery, College of Medicine, King Saud University, 2Radiation Oncology Department, King Fahad Medical City, 3Radiation Oncology Department, 4Histopathology Department, Comprehensive Cancer Center, King Fahad Medical City, Riyadh, Saudi Arabia; 5Radiation Oncology Department, National Cancer Institute, Cairo, Egypt Background: Skull calvarium and dura mater are rare sites of distant metastasis, and mostly have been reported in lung, breast, and prostate malignancies. However, the calvarial and dural metastases from papillary thyroid cancer (PTC) are rare entities and pose diagnostic and therapeutic challenges. To date, only seven cases of calvarial metastasis with intracranial extension from PTC have been reported in literature. However, true dural metastasis from PTC has not yet been reported. Case presentation: A 65-year-old Saudi woman presented with 6 months history of painful posterior scalp lump, 7 years after initial diagnosis of PTC. Computed tomography and magnetic resonance imaging showed occipitoparietal calvarial lesion with massive intracranial extension. Another para-sagittal lesion was found at the top of corpus callosum mimicking a meningioma. Histopathology of para-sagittal lesion and the biopsy of calvarial mass confirmed the diagnosis of metastatic PTC. After surgical resection, residual tumors were treated with postoperative intensity-modulated radiation therapy. At 13 months of follow-up, patient was alive and without any signs of recurrence. Conclusion: Calvarial and dural metastases from PTC are extremely rare clinical entities. Surgical resection followed by postoperative radiotherapy is the treatment of choice. However, for such cases, multidisciplinary approach can prolong the treatment outcome and survival. Keywords: papillary thyroid carcinoma, calvarial metastasis, intracranial extension, true dural metastasis