[Renal failure as a first sign of tethered cord syndrome in the adult].

where we were surprised by several images indicative of ependymal implants in both anterior horns of the lateral ventricles, hyperintense in T1 sequence and hypointense in T2 (Fig. 1) without contrast enhancement, which did not correspond to blood-borne deposits in the sequence of magnetic susceptibility. In the control dorsal MRI, there were signs of myelopathy with traces of haemosiderin; at the boundary between D9 and D10 segments, we found a 1 cm lesion located in the right posterolateral region of the spinal cord. Not captured by IVC, it was hyperintense in T1 and hypointense in T2, with radiological semiology characteristic of melanin (Fig. 1). The ependymal implants had doubled in size in the brain MRI after 1 month of evolution (Fig. 1), a fact that strengthened the diagnosis of rapidly progressing meningeal melanocytoma with seeding or a multifocal origin. Despite this, the patient remained clinically stable with not only her spinal cord lesion but also in her cognitive deficit during the 3 months that she stayed at our centre. In the end, she was sent to the oncology department of her reference hospital to be assessed for other treatment options. Melanotic cells are derived from the neural crest during embryonic development; they are present in a healthy adult and are the origin for pigmented leptomeningeal tumours. Among these, melanocytoma originates in the spinal cord half the time.1 Although these tumours generally have a good prognosis when treated with a complete resection or incomplete surgery plus adjuvant radiotherapy, according to the series of cases with evolution at 5 years, the percentage of local relapses is not negligible; neither is the leptomeningeal progression and seeding, which are less frequent.2 In cases described on seeding, the primary location is in the posterior fossa, with implants at a spinal level.3,4 This can occur after a complete tumour resection and a period of clinically-stable years. This possibility was considered in the case presented, but it seemed improbable due to the short time of evolution between the surgery and the detection of cerebral lesions. Despite the fact that in this case the pathological anatomy did not reveal malignancy, we saw rapid tumour progression, with a possible multifocal origin. This has been published on very few occasions; consequently, the prognosis is uncertain in this case. In references that have been found, it is attributed to a possible aggressive course and a bad prognosis.5,6 Finally, we would like to stress that we had previously considered a histological review of this tumour in order to modify the various treatment regimens and improve the outcome.