대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Metastasis of Osteosarcoma

Radiologic Findings

The chest radiograph reveals a dense consolidation in BLL, and several calcified nodules are scattered in both of the lung. Note the density of the consolidation is similar to that of the rib. On CT, the right and left paratracheal and subpulmonic lymph nodes are enlarged with the contained dense calcification. The multiple nodules in both lung display a dense internal calcification. Some nodules in the right lower lobe are conglomerated. Note the subcutaneous mass at the right anterior chest wall - it also has a distinctive ossification. Additionally, a round ossified metastatic lesion is detected at the left renal parenchyma which looks like renal stone.

This patient complained neuralgia in his left thigh one month ago while walking, and the mass was detected from the left proximal femur on MRI. The mass shows an ill-defined intramedullary bone tumor with the periosteal reaction on Gd-enhanced fat suppressed T1-weighted coronal scan. It was confirmed as the osteosarcoma. He is taking now a radiation therapy and a chemotherapy.

Brief Review

Osteosarcom is the most comon malignant bone tumor in children. It initially metastasizes hematogeneously as other sarcoma. So, most metastases are involved wtih the lungs, although recent studies have suggested a higher rate of extrapulmonary metastases in patients treated by surgery and adjuvant chemotherapy. At autopsy, the most frequent metastatic sites are the lungs (95%), bones (50%), and kidneys (12%) (1).

According to Kim et al (2), 45 out of the 134 patients had metastasis from osteosarcoma. Thirty-two of them had only lung metastasis and 13 had extrapulmonary metastasis. Among 13 patients with extrapulmonary metastasis, 6 had metastatic lesions in another bone other than the primary site and 4 patients had lymph node metastasis. Other metastatic sites included the pleura (n=2), liver (n=2), pancreas (n=1), kidney (n=1), small bowel (n=1), peritoneum (n=1), muscle (n=1), subcutaneous fat layer (n=1), and the pulmonary artery (n=1).

Seo et al. (3) reported that calcification or ossification can occur in metastatic nodules from an osteosarcoma or chondrosarcoma, even though calcification of a pulmonary nodule is usually suggestive of its benign nature such as granuloma or hamartoma. Metastatic nodules from a synovial sarcoma, giant cell tumor of the bone, and carcinomas of the colon, ovary, breast and thyroid may calcify. Calcification can also be seen in treated metastatic choriocarcinomas.

Several mechanisms are responsible for tumoral calcification: (a) bone formation in an osteosarcoma or chondrosarcoma; (b) dystrophic calcification in a papillary carcinoma of the thyroid, giant cell tumor of the bone, synovial sarcoma, or treated metastatic tumor; and (c) mucoid calcification in a mucinous adenocarcinoma of the gastrointestinal tract and breast.

References

1. Price CH, Jeffree GM. Metastatic spread of osteosarcoma. Br J Cancer 1973;28:515-524

2. Kim SJ, Choi J-A, Lee SH, et al. Imaging findings of extrapulmonary metastases of osteosarcoma. Clin Imaging. 2004;28:291-300

3. Seo JB, Im J-G, Goo JM, et al. Atypical Pulmonary Metastases: Spectrum of Radiologic Findings. Radiographics 2001;21:403-417

Keywords

Lung, Chest wall, Malignant tumor,