Extra-Axial Mass in the Foramen Magnum Causing Cervical Compressive Myelopathy as a Complication of Rosai-Dorfman Disease

Dear Editor, Sinus histiocytosis with massive lymphadenopathy, or Rosai-Dorfman disease (RDD), is a rare histiocytic proliferative disorder characterized clinically by massive adenopathy and systemic symptoms. The extranodal manifestations that occur in 43% of all RDD patients most frequently affect the skin, respiratory tract, paranasal sinuses, orbits, and bone.1 CNS involvement is extremely rare (in <5% of cases), and usually consists of an extra-axial durabased lesion; the most common locations are the convexity and the base of the skull.1 We present a case of RDD with extranodal involvement at the foramen magnum extending toward the cervical spinal canal and resulting in compressive cervical myelopathy. To the best of our knowledge, only three cases of RDD displaying spinal cord compression secondary to craniocervical junction involvement have been reported since the disease was first described in 1969.2-4 Our patient was a 28-year-old man who had been diagnosed with RDD in childhood. In September 2012, he was seen in the neurology department due to a 1-week history of loss of strength in his right arm. The neurological examination showed mild tetraparesis (4+/5 in the left limbs, with more severe right arm involvement: 3/5 proximally and 1–2/5 distally), symmetrical 2/4 deep tendon reflexes, and tactile hypoesthesia and hypoalgesia in the right C5–C8 territories. Brain MRI revealed extensive nasal and sinus involvement (Fig. 1A). A cervical MRI scan revealed an extra-axial lesion in the posterior region of the craniocervical junction and extending from the foramen magnum to the base of the odontoid process. This mass was causing severe foramen magnum stenosis and compressive cervical myelopathy (Fig. 1B and C). After assessment by the neurosurgery department, he underwent suboccipital craniectomy and complete tumor resection. Cytology study of the excised tissue revealed that the spinal cord parenchyma was infiltrated by histiocytes exhibiting emperipolesis (lymphophagocytosis). Immunohistochemical staining was positive for the markers CD68 and S-100 and negative for CD1a (Fig. 1D-I). The postoperative results were favorable, with the neurological symptoms resolving completely. After 4 years of follow-up, our patient is still being treated with oral corticosteroids and has presented no additional extranodal lesions in the foramen magnum. CNS involvement is rare in RDD, and it usually presents in the form of a well-defined, solitary, extraparenchymal supratentorial dura-based lesion resembling a meningioma in neuroimaging scans.3 Lesions located in the posterior fossa and extending to the cervical spinal canal, as in our case, are rare. Accompanying focal neurological signs depend mainly on the location of the primary lesion; these signs may be subacute, chronic, or recurrent. In all three previously reported cases Sira Carrasco-García de León José Manuel Flores Barragán Fernanda Relea Calatayud Osvaldo Balcazar Rojas