[79] Skeletal Metastases: An Analysis of Patients with Unknown Primary Site

Cora Uram-Tuculescu, Gregory Domson, William C Foster, Ema Dragoescu. Virginia Commonwealth University, Richmond, VA

Background: Pathologic evaluation of bony metastases in cases with prior history malignancy is usually straightforward. However, when a patient does not have a known malignancy, nor a complete radiologic work-up, pathologic evaluation of bony metastases is more challenging, becoming a process of elimination of potential primary sites. In our study we aim to investigate if there are certain common features characteristic for this subset of bony metastases. Having knowledge of the malignancies more likely to produce bony metastases before manifesting at the primary site helps the pathologist to be more efficient in the work-up of these cases.
Design: All cases of bony metastases diagnosed at our center between 2005-2010 were retrieved. Hematologic malignancies were excluded. Site of involvement, clinical and radiologic data, history of malignancy, and pathologic diagnosis were recorded. Sites of involvement were: central (axial skeleton), proximal (above elbows/knees), and distal (below elbows/knees). Information collected on patients with bony metastases and unknown primary site was compared to that of patients with bony metastases and known malignancy.
Results: 119 bone metastases were identified and 40 cases (33.6%) had no known primary tumor at the time of presentation. Our data suggests that skeletal metastases in this group are more likely to be adenocarcinomas and central in location.

Table 1. Skeletal metastases with unknown primary site versus known primary site
  Cases with unknown primary site (40)Cases with known primary site (79)
SiteCentral21 (52.5%)31 (39.2%)
 Proximal13 (32.5%)42 (53.2%)
 Distal6 (15%)6 (7.6%)
Pathologic fracturePresent15 (37.5%)33 (41.8%)
 Absent25 (62.5 %)46 (58.2%)
Pathologic diagnosisAdenocarcinoma22 (55%)34 (43.1%)
 Squamous cell carcinoma6 (15%)9 (11.4%)
 Poorly differentiated carcinoma3 (7.5%)5 (6.3%)
 Renal cell carcinoma5 (12.5%)13 (16.4%)
 Thyroid carcinoma1 (2.5%)6 (7.6%)
 Other3 (7.5%)12 (15.2%)

The most likely primary sites were lung (30%) and kidney (12.5%). However, in 37.5% cases a primary site could not be determined based on pathology alone. Bony metastases in cases with prior history of malignancy were from lung (26.6%), breast (25.4%), kidney (16.4%), prostate (8.8%), thyroid (7.6%), or other (15.2%).
Conclusions: In patients with skeletal metastases and unknown malignancy at presentation the two most likely primary sites are lung and kidney, however in a large proportion of cases the primary site cannot be determined by pathologic evaluation alone.
Category: Bone & Soft Tissue

Monday, March 19, 2012 1:00 PM

Poster Session II # 39, Monday Afternoon


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