PMC3658261_01
The (A) plain radiograph and (B) computed tomography scan shows unexpectedly large sized, bony structured (radiodense) loose bodies (black arrow and blue arrows) at the lateral compartment of the knee. (C) Magnetic resonance imaging examination shows osteocartilaginous structures (unusual large sized loose bodies, two small and one large) joining with the lateral meniscus.. Note: The lateral meniscus has lost its healthy appearance and has been overshadowed (orange arrows) by osteocartilaginous structures.
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The plain radiograph and computed tomography scan showed unexpectedly large and bony (radiodense) structures as loose bodies (a main large one and two small ones) at the lateral compartment of the knee (Figure 1A and B). Magnetic resonance imaging showed that there were no irregularities or thickening of the cartilaginous cap greater than 1 cm (Figure 1C).
A histologic preparation of a synovial solitary osteochondroma (H&E, x 10 obj) revealed the characteristic pattern of an osteochondroma covered by a thick cartilaginous cap formed with columnar arrangement of chondrocytes typical for osteochondroma (black arrows [A]). The fibrous capsule was adjacent to the fibrocartilaginous meniscus tissue (yellow arrows [B]). At the chondro-osseous junction, an osteoid matrix with osteocytes forming bony trabecula is apparent at the base of the cap (blue arrows [C]).
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At the chondro-osseous junction, endochondral ossification, forming bony trabecula, was found (Figure 2).