Chordoma of the posterior mediastinum accompanied by synchronous lesion

1. Hospital Casa de Portugal, Rio de Janeiro, RJ, Brazil. 2. Instituto Estadual do Cérebro Paulo Niemeyer, Rio de Janeiro, RJ, Brazil. Mailing address: Dr. Tiago Medina Salata. Rua do Bispo, 72, Rio Comprido. Rio de Janeiro. RJ, Brazil, 20261-064. E-mail: tiago_salata@yahoo.com.br. imaging with absence of typical movement disorder symptoms (hemichorea-hemiballism). J Radiol Case Rep. 2013;7:1–9. 8. Machado VS, Silva Junior NA, Queiroz LS, et al. Central nervous system involvement in sarcoidosis. Radiol Bras. 2015;48:334–5. 9. Dultra AHA, Noro F, Melo ASA, et al. Primary intercavernous lymphoma of the central nervous system. Radiol Bras. 2015;48:337–8. 10. Ribeiro BNF, Lima GA, Ventura N, et al. Chronic kernicterus: magnetic resonance imaging findings. Radiol Bras. 2016;49:407–8. 11. Langer FW, Suertegaray G, Santos D, et al. Hemichorea-hemiballism: the role of imaging in diagnosing an unusual disorder in patients with nonketotic hyperglycemia. Radiol Bras. 2016;49:267–8. 12. Ribeiro BNF, Salata TM, Borges RS, et al. Posterior reversible encephalopathy syndrome following immunoglobulin therapy in a patient with Miller-Fisher syndrome. Radiol Bras. 2016;49:58–9. 13. Campos LG, Trindade RAR, Faistauer A, et al. Rhombencephalitis: pictorial essay. Radiol Bras. 2016;49:329–36. 14. Georgeto SM, Zicarelli CAM, Gariba MA, et al. T1-weighted gradientecho imaging, with and without inversion recovery, in the identification of anatomical structures on the lateral surface of the brain. Radiol Bras. 2016;49:382–8.

Colorectal perforation is a serious complication of a barium enema. Although its exact occurrence is difficult to establish, some studies indicate a mean incidence of 0.02-0.23% among the exams performed, with a mortality rate of up to 50% (1,2) . The sites most commonly affected are the sigmoid colon and the rectum.
Etiologically, colorectal perforations cause by enema administration can be divided into those that are iatrogenic and those that are secondary to weakness of the colorectal wall. Iatrogenic perforations can occur as a result of forced introduction of the catheter into the anterior rectum wall, balloon hyperinflation, or excessive hydrostatic pressure during contrast injection. Perforations secondary to colorectal wall weakness occur in patients with a history of inflammatory bowel disease, acute diverticulitis, or obstructive colorectal processes, as well as in those who have recently undergone a surgical procedure, are of advanced age, or are on corticosteroid therapy, any of which make these patients more susceptible to perforation during the administration of the enema (3) . In such high-risk cases, the use of water-soluble contrast should be considered.
The symptoms of colorectal perforation are variable, depending on the location and size of the lesion, and can initially manifest as abdominal pain progressing to peritonitis, sepsis, and shock. However, in fewer than 10% of cases, patients are asymptomatic in the first days after the examination, and the radiologist can be the first to suggest perforation, as was the case in the patient described here (3,4) .
In cases of colorectal perforation in which the patient is stable, the puncture is small, and there is no fecal matter in the gastrointestinal tract or retroperitoneum, conservative treatment is adopted. Otherwise, exploratory laparotomy is necessary (5) .
Although barium enema is a routine examination, it should be performed with caution. In cases of perforation resulting from the examination, treatment should be initiated early and should be tailored to the type of injury, as well as to the clinical status of the patient, thus reducing the morbidity and mortality associated with the condition.

Dear Editor,
A 53-year-old male patient with a 3-month history of back pain presented with progressive paraparesis, although without loss of sphincter control. Magnetic resonance imaging (MRI) of the dorsal spine ( Figures 1A and 1B) showed an expansile lesion with lobulated contours, involving the posterior mediastinum and extending to the vertebral canal, thus reducing the amplitude of the vertebral canal and compressing the medulla.
A synchronic lesion of similar appearance, affecting the 12th dorsal vertebra, was observed. The histopathological study revealed large cells with vacuolated cytoplasm and partially vesicular nuclei (some demonstrating prominent nucleoli), with the appearance of physaliferous cells (from the Greek physallis, or bubble), consistent with a diagnosis of chordoma ( Figure 1C).
Recent studies in the radiology literature of Brazil have highlighted the importance of imaging methods in improving the diagnosis of intrathoracic alterations (1)(2)(3)(4)(5) . Chordomas are slow-growing malignancies derived from primitive remnants of the notochord. They typically occur in the fifth and sixth de-   life (6,7) , with a slight predilection for males and preferential involvement of the sacrococcygeal region (50%), followed by the spheno-occipital region (35%), cervical spine, and lumbar spine, occurring only rarely in the dorsal spine and posterior mediastinum (6)(7)(8) . Symptoms often appear only after the lesion has reached large proportions, with local invasion affecting neurovascular structures. Local recurrence is common when complete resection was not possible.
The differential diagnoses of chordoma include metastases, chondrosarcoma, multiple myeloma, neurogenic tumors, among others. Although imaging methods help delineate the lesion, the diagnosis is made on the basis of the histopathological analysis (7) .
On MRI, most chordomas show isointense or hypointense signals in T1-weighted sequences, whereas they show hyperintense signals in T2-weighted and short-tau inversion-recovery sequences, reflecting their high water content, some lesions containing fibrous septa and therefore showing low signal intensity in T2-weighted sequences (6)(7)(8) . Gadolinium contrast enhancement tends to be moderate and heterogeneous (6,8) . Lesions are often accompanied by bone erosion, which was not observed in the case reported here. Recent studies have highlighted the use of diffusion-weighted imaging in the differentiation between chordomas and chondrosarcomas, reporting that the latter show higher apparent diffusion coefficients (9,10) .
In addition to an unusual site of involvement, our patient presented the peculiarity of a synchronous lesion. Although some authors have reported similar cases (7,8,11,12) , there is no specific criterion for differentiating between a multicentric chordoma and metastatic dissemination. We believe that our case could represent dissemination to the cerebrospinal fluid, because there was involvement of the vertebral canal.
The treatment of choice for chordoma is surgical resection with adjuvant radiotherapy, resulting in a disease-free period approximately 2.5 years longer than that achieved after surgical treatment alone (7) . Because chordoma is resistant to conventional radiotherapy, other modalities, such as stereotactic radiosurgery, are used. Chordoma does not respond well to chemotherapy, antitumor activity having been observed, in small studies, only with the use of imatinib mesylate (13) .
Albeit rare, a diagnosis of chordoma should be considered in patients with lesions affecting the posterior mediastinum. In addition, the possibility of synchronous lesions should be investigated in such patients.