INTRODUCTION: Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is a powerful tool for the assessment of mediastinal lymphadenopathy. We present a patient who was initially diagnosed with metastatic carcinoid tumor. On the basis of immunohistochemical staining of mediastinal lymph node biopsy obtained via EBUS-TBNS, the correct diagnosis was made.
CASE PRESENTATION: A 25-year-old woman was referred to our institution for management of metastatic tumor. She had presented to an outside hospital with abdominal pain of two weeks duration. A CT scan of the abdomen revealed an 8 x 9 x 7 cm liver mass. She reported chronic coccygeal pain worsening over several years that she attributed to a presumed coccyx fracture. Physical examination revealed a hard, fixed, tender mass at the base of the coccyx. Percutaneous liver biopsy was reported as consistent with carcinoid tumor, as supported by clusters of bland cells with hyperchromatic nuclei. The results of immunohistochemical stains were equivocal. An octreotide scan was negative, suggesting an alternative diagnosis. A CT scan of the chest was performed at our institution due to complaints of dyspnea and cough, revealing massive mediastinal lymphadenopathy and innumerable small pulmonary nodules suggestive of metastatic disease. The patient was referred for EBUS-TBNA as the constellation of clinical findings was unusual for carcinoid tumor. Lymph node histology demonstrated clusters of large mildly pleomorphic malignant epithelioid cells with focal fibrillary cytoplasmic processes, perivascular pseudorosette formation, mitotic activity, and tumor necrosis. Based on the unusual histology, multiple immunohistochemical stains were performed on the aspirate cell block. The tumor cells were extensively positive for vimentin, GFAP, CD56, and NSE, focally positive for EMA, CD99, AE1/3, and S100, and negative for CAM5.2, synaptophysin, and chromogranin. The histologic features and staining pattern supported a diagnosis of metastatic extraspinal ependymoma or myoepithelial carcinoma rather than a carcinoid tumor. The original liver biopsy was restained at our institution and found to have the same staining pattern as the mediastinal lymph node biopsy. In addition, the mass adjacent to the coccyx was surgically excised and was consistent with an extraspinal ependymoma. The coccygeal mass, liver mass, and mediastinal lymph nodes all demonstrated uniform histologic and immunohistochemical features.
DISCUSSION: To our knowledge, this is the first report of utilizing EBUS-TBNA in the diagnosis of extraspinal ependymoma. Primary extraspinal ependymoma is a rare malignancy with approximately 100 cases reported in the literature. The majority occur in the sacrococcygeal region, often being mistaken for benign pathology such as a pilonidal cyst. Fewer than 20% of cases metastasize, and have been reported in the lungs, pleura, bone, regional lymph nodes, and skin.(1) This case demonstrates that material obtained via EBUS-TBNA from mediastinal lymph nodes is adequate to be analyzed by modern microscopical and immunohistochemical techniques to make specific diagnoses of malignant processes arising in distant locations from the lung.
CONCLUSIONS: Accurate diagnosis of disseminated malignancy requires a correlation of clinical, radiologic, and pathologic information. EBUS-TBNA is a relatively noninvasive yet powerful tool for histologic examination and staining with multiple tumor markers. Careful attention to immunohistochemical staining of such biopsies may assist in the diagnosis of unexpected and uncommon malignancies.
Reference #1 Ma YT, Ramachandra P, Spooner D. Primary subcutaneous sacrococcygeal ependymoma: a case report and review of the literature. Br J Radiol 2006; 79: 445-447.
DISCLOSURE: The following authors have nothing to disclose: Joshua Farkas, Llewellyn Foulke, Anwar Haque, Marc Judson, Mark Napier
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