Cytogenetic Evaluation of Osteolipoma: A Study of 3 Unique Cases.
Karen J Fritchie, Kathleen W Rao, Jordan B Renner, Robert J Esther. Cleveland Clinic, OH; University of North Carolina Hospitals, Chapel Hill
Background: Osteolipoma is a rare variant of lipoma consisting of a variable admixture of mature adipose tissue and mature lamellar bone. While typical lipomas are usually not a diagnostic challenge, osteolipomas are rare and may be misclassified by pathologists as benign osseous/cartilaginous lesions or even atypical lipomatous tumors. Translocations involving 12q13-15 are the most common alterations seen in lipomas, and as such, the identification of translocations involving 12q13-15 may aid in the correct diagnosis of osteolipoma.
Design: We examined the clinical and radiologic findings, histologic features and karyotypes of three mature lipomatous tumors with bone formation. These tumors were initially classified as lipoma, atypical lipomatous tumor and juxta-articular chondroma.
Results: Two lesions encased the patellar tendon, while the third abutted the extensor carpi radialis longus and brevis. No connection to bone was noted in any of the lesions. The lesions measured 5.2 cm, 4.0 cm and 3.4 cm. Histologic examination revealed mature lipomatous tumors with varying amounts of chondroid and osseous elements without cytologic atypia. Cytogenetic analysis reveal a t(3;12)(q27;q13-15) in all three cases, with the following abnormal karyotypes: 46,XX,t(3;12) (q27;q15) , 46,XX,t(3;12) (q27;q13)  / 46,XX, and 46,XY,t(3;12) (q27;q14-15)  / 46,XY.
Conclusions: Osteolipomas are uncommon benign lipomatous tumors that may present a diagnostic challenge for pathologists unfamiliar with this entity. Cytogenetic analysis utilizing fresh tissue can aid in the diagnosis of these tumors and prevent misclassification.
Category: Bone & Soft Tissue
Monday, February 28, 2011 1:00 PM
Poster Session II # 18, Monday Afternoon