Diffuse spinal cord metastasis after resection of SMARCB1 sinonasal carcinoma manifesting with a right foot drop-a case report.

Introduction: The sinonasal carcinoma are rare tumors of the head and neck. The undifferentiated sinonasal carcinoma subtypes are constantly being explored and new mutations, with different prognosis markers and biological behaviors are being described. The SMARCB1 negative sinonasal carcinoma subtypes have been recently described with few reports of leptomeningeal and spinal cord invasion.

Case Presentation: This study presents the case of a 59-year-old woman, with no previous disease, presenting initially with epistaxis that evolved to cranial nerve deficits and a left eye complete oftalmoplegia. After diagnostic investigation, she had a diagnosis of a left ethmoid sinus sinonasal carcinoma. Following resection of the tumor, she evolved with a right foot drop that eventually has been linked to diffuse spinal cord impairment. The histopathological diagnosis confirmed a SMARCB1 negative sinonasal carcinoma. Due to the diffuse metastasis, she underwent palliative care and died eight months after the surgery.

Discussion: Spinal cord metastasis may manifest with different clinical signs. Our case shows a rare manifestation of SMARCB1-deficient sinonasal carcinoma, a new subtype of sinonasal carcinoma, summarizing the importance of a high grade of suspicion of spinal cord invasion on these patients. SMARCB1 sinonasal carcinomas are rare new tumors of the head and neck, whose biological behaviors are yet to be explored. To the best of our knowledge, this is one of the few case reports describing simultaneous spread of this tumor to the central nervous system and spinal cord.