Extraosseous Benign Notochordal Cell Tumor Originating in the Lung

Abstract

Benign notochordal cell tumors (BNCTs) are tumors originating in the axial skeleton, where chordomas occur. Although very rare, some cases of extraosseous chordoma, such as in the soft tissue and lungs, have been reported. We report a case of a primary tumor showing the notochordal characteristics of BNCTs within the axial skeleton.An asymptomatic 57-year-old woman presented with an abnormal shadow on her chest radiograph; chest computed tomography revealed a well-defined round nodule. The resected sample tissue contained a jelly-like small nodule. Histologically, it was identified as a BNCT, based on minimal nuclear atypia, extremely low mitotic activity within the tumor cells lying in a sheet-like arrangement, and focal immunopositivity for brachyury.This is the third case report of BNCT originating in the lungs; BNCTs are considered asymptomatic tumors that are identified by using highly developed chest imaging technology; however, our findings also suggest that these notochordal tumors may potentially originate from extraosseous sites that lack ideal precursor cells. Our case suggests that notochordal tumors can arise from organs that are unrelated to known notochordal development.

Benign notochordal cell tumor of the lung: Report of a case

“…The present tumor showed characteristic clinical and pathological findings that were similar to those of previously reported cases of pulmonary BCNT 10–14 . Many other pulmonary neoplasms, such as chondroma, hamartoma, pleomorphic adenoma, myoepithelioma, perivascular epithelioid cell tumor (‘clear cell tumor’), metastatic carcinoma, metastatic chordoma, extraskeletal myxoid chondrosarcoma, and a recently reported entity, pulmonary myxoid sarcoma with EWSR1‐CREB1 fusion, 15 were considered in the differential diagnosis, but these were ruled out on the basis of pathological or clinical findings, and the immunoreactivity for brachyury established the notochordal differentiation of tumor cells 16 …”

“…First, a small number of entrapped alveolar epithelial cells were found in the peripheral area of the tumor. This finding, which was noted by Takahashi et al ., 14 suggests that the growth pattern of pulmonary BNCTs, although they appear sharply demarcated and have a round and smooth margin, is not necessarily expansile but infiltrative, incorporating the adjacent alveolar epithelium into the tumor. In this regard, we should note that Yamaguchi et al .…”

“…In the case of chordoma, blood vessels are mostly restricted to the fibrous septa separating the lobules of neoplastic cells and very rare within the tumor lobules 1,18 . BNCT, regardless of its location, mostly lacks intra‐tumoral blood vessels 6,14 . We suspect that this lack of vasculature suppresses the growth of BNCT (almost all reported cases of pulmonary BNCT are smaller than 2 cm in diameter).…”

“…Tumors showing histopathological and immunohistochemical features similar to those of chordoma or BNCT infrequently occur in the extra‐axial skeleton, 8 soft tissue 9 or viscera. It is interesting that the occurrence of notochordal neoplasms in the viscera has almost been confined to the lung to date 10–14 . However, there remain some problems to be resolved concerning the clinical behavior, pathological features, histogenesis and nosologic positioning of these rare pulmonary lesions, and the accumulation of further cases is required to overcome these problems.…”

Multiple primary chordomas of the lung

“…However, such gene abnormalities have not been reported in humans. Interestingly, four cases of pulmonary benign notochordal cell tumors (BNCT) have been reported recently [ [5] , [6] , [7] ]. Although it has not yet been documented that chordomas arise from BNCTs in the lungs, pulmonary BNCT is considered a potential precursor of classic chordoma [ 5 , 6 ].…”