J Korean Soc Radiol.  2018 May;78(5):340-344. 10.3348/jksr.2018.78.5.340.

Retroperitoneal Extraskeletal Osteosarcoma without Calcification Mimicking Pancreas Tumor: CT Imaging of a Case Report

• Kim JW
• Bae KE
• Park KM
• Kim JH
• Jeong MJ
• Kim SH
• Kim JY
• Kim SH
• Kang MJ
• Lee JH
• Kim TG

• KMID: 2410723
• DOI: http://doi.org/10.3348/jksr.2018.78.5.340

Abstract

Retroperitoneal extraskeletal osteosarcoma is a rare tumor. Typical imaging findings include a soft tissue mass accompanied with internal calcifications. The authors encountered a case involving a 44-year-old woman with a large retroperitoneal extraskeletal osteosarcoma, without calcification, that mimicked a pancreatic tumor. The present report highlights computed tomography features of retroperitoneal extraskeletal osteosarcoma, followed by a brief literature review. It is challenging for radiologists to diagnose retroperitoneal masses. However, in patients who present with large retroperitoneal masses, combined with clinical information including the elevation of serum alkaline phosphatase levels, retroperitoneal extraskeletal osteosarcoma should be considered in the differential diagnosis, even if the mass does not exhibit a gross calcification on the imaging.

MeSH Terms

Adult
Alkaline Phosphatase
Diagnosis, Differential
Female
Humans
Osteosarcoma*
Pancreas*
Retroperitoneal Space
Tomography, X-Ray Computed
Alkaline Phosphatase

Figure

• 

  Fig. 1 Retroperitoneal extraskeletal osteosarcom without calcification mimicking pancreas tumor in a 44-year-old woman. A-D.Abdominopelvic computed tomography with contrast enhancement. A.No gross radiopaque calcification in the mass is apparent in the pre-contrast image. B, C, D.On postcontrast scan, the mass is located in the left retroperitoneal space and obscures the pancreas body and tail. Persistent heterogeneous enhancement is apparent, especially in the peripheral portion. The central portion of the mass is non-enhancing and low density. E.Endoscopic ultrasonography revealing a mass > 7 cm in size, with a heterogeneous echotexture composed of solid and cystic portions. The pancreas body to tail portion is not visible. F. Gross cross-section specimen (upper) revealing a cystic and solid tumor. On microscopy (lower, hematoxylin and eosin, × 100), infiltration of the neoplastic spindle or plump cells with neoplastic bone formation is apparent (arrow), accompanied by non-neoplastic osteoclast-type giant cells (arrowhead).

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