Primary lung chordoma: a case report

Abstract

Background: Chordoma, a rare malignant tumor arising from notochordal tissue, usually occurs along the spinal axis. Only a few published reports of primary lung chordomas exist. Herein, we present a case of primary lung chordoma and discuss important considerations for diagnosing rare chordomas.

Case presentation: We report a case of primary lung chordoma in a 39-year-old male with a history of testicular mixed germ-cell tumor of yolk sac and teratoma. Computed tomography revealed slow-growing solid lesions in the left lower lobe. We performed wedge resection for suspected germ-cell tumor lung metastasis. Histologically, large round or oval cells with eosinophilic cytoplasm were surrounded by large cells with granular, lightly eosinophilic cytoplasm. Tumor cells were physaliphorous. Immunohistochemistry was positive for brachyury, S-100 protein, epithelial membrane antigen, vimentin, and cytokeratin AE1/AE3, suggesting pulmonary chordoma. Re-examination of the testicular mixed germ-cell tumor revealed no notochordal elements. Although some areas were positive for brachyury staining, hematoxylin and eosin (HE) staining did not show morphological features typical of chordoma. Complementary fluorescence in situ hybridization (FISH) of the lung tumor confirmed the absence of isochromosome 12p and 12p amplification. Thus, a final diagnosis of primary lung chordoma was established.

Conclusions: In patients with a history of testicular mixed germ cell tumors, comparison of histomorphology using HE and Brachyury staining of lung and testicular tumors, and analyzing isochromosome 12p and 12p amplification in lung tumors using FISH is pivotal for the diagnosis of rare lung chordomas.

Keywords: Brachyury; FISH; Isochromosome 12p; Lung chordoma; Testicular mixed germ-cell tumor.

Fig. 1

The pulmonary nodule, located in the left lower lobe on computer tomography, is a round, solid nodule with a well-defined border. a 13 years, b 8 years, c 3 years, and d 2 weeks before surgery. e Intraoperative findings of the pulmonary nodule

Fig. 2

The tumor is 8 × 5 × 8 mm, well demarcated, white, and jelly-like

Fig. 3

Microscopic examination revealing (a) solid sheets of neoplastic cells (× 40). The tumor is composed of (b) large round or oval cells with eosinophilic cytoplasm surrounded by (c) large cells with granular lightly eosinophilic cytoplasm (× 400). d The tumor exhibits pleural invasion and (e) Elastica van Gieson (EVG) staining confirms pleural disruption (× 100). f The tumor exhibits lymphatic invasion, and (g) Podoplanin (D2-40) staining confirms the presence of tumor cells in the lymphatic vessels (× 100). h Immunohistochemical staining shows the tumor cells, positive for brachyury (× 400). i Alcian blue-periodic acid-Schiff staining shows a myxoid intercellular matrix, positive for Alcian blue, surrounding the tumor cells (× 400)

Fig. 4

Microscopic findings of a testicular mixed germ-cell tumor of the yolk sac and teratoma (× 100). a In the yolk sac component of the tumor, small cells proliferate in cystic, luminal, and microcystic forms and Schiller-Duval body, which has a central vessel surrounded by tumor cells, is seen. b Both the yolk sac and teratoma components are seen. The squamous and glandular epithelium of the teratoma component are seen. c In another teratoma component, cartilage, adipocytes, and epithelium, such as gastrointestinal epithelium, are seen. d An area positive for brachyury. e HE staining of the same area as (d). These epithelioid cells are findings derived from teratoma, not chordoma. None of the areas positive for brachyury show notochordal cells with hematoxylin and eosin staining (× 400)

Fig. 5

FISH analysis of the lung chordoma. Green signals represent the centromere of chromosome 12, while red signals correspond to the short arm of chromosome 12. The ratio of red to green signals was 1:1. FISH analysis showed no appearance of isochromosome 12p