Giant cell tumor of bone - lung metastasis
This woman presented with a persistent chesty cough following a presumed viral illness. A chest x-ray show several scattered sub-pleural nodules, which were subsequently removed surgically via lung wedge excisions. Upon questioning the clinical team, a previous history of primary giant cell tumor of the bone became known.
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The sections from each lung wedge showed similar features, with each containing a well circumscribed, solid lesion with a diffuse patternless architecture and composed of relatively monomorphic mononuclear cells along with somewhat evenly distributed multi-nucleated giant cells. Mononuclear and multinucleated cells display similar nuclear morphology. Mitotic figures are present in small numbers. There is mild focal hemorrhage and no necrosis. The surrounding alveolated lung parenchyma shows no significant abnormality.
40x H&E: Low-power view showing sharp circumscription from otherwise normal-appearing alveolated lung parenchyma. The tumor is solid and displays a diffuse, patternless architecture.
100x H&E: Medium-power view showing patternless pattern and mononuclear cells with relatively evenly distributed multinucleated cells.
200x H&E: High-power view showing relatively monophorphous appearance to cells. At this power, the similarity in nuclear features between mononuclear and multinucleated cells can be appreciated. There is no significant nuclear pleomorphism.
Whilst primary giant cell tumors (GCT) of bone are often considered benign in nature (albeit locally aggressive), distant metastases occur in a small minority (between 1-9%, depending on the study), with pulmonary metastases being the most common site.
Unlike most other distant metastatic diseases, metastatic GCT is not necessarily associated with a poor prognostic outcome, with metastasectomy (where possible) being curative in many patients.
In the setting of known primary GCT this diagnosis is relatively straightforward, however, in the absence of such a history, a wider differential diagnosis must be considered.
- 1. Viswanathan S and Jambhekar NA, Metastatic Giant Cell Tumor of Bone: Are There Associated Factors and Best Treatment Modalities?; Clin Orthop Relat Res. 2010 Mar; 468(3): 827–833 Pubmed complete article