Kransdorf M J, Meis J M
Department of Radiologic Pathology, Armed Forces Institute of Pathology, Washington, DC 20306-6000.
Radiographics. 1993 Jul;13(4):853-84. doi: 10.1148/radiographics.13.4.8356273.
Extraskeletal osseous and cartilaginous tumors and tumorlike conditions of the extremities can often be differentiated radiologically; for those that cannot, knowledge of the spectrum of lesions will allow a suitably ordered differential diagnosis. Of the osseous lesions--myositis ossificans, fibro-osseous pseudotumor, fibrodysplasia ossificans progressiva, soft-tissue osteoma, and extraskeletal osteosarcoma--all but myositis ossificans are relatively rare. Myositis ossificans has a distinct mineralization pattern that can be observed radiologically as a peripheral rim of lamellar bone. Fibro-osseous pseudotumor typically occurs in the digits of the hand and lacks the well-defined zoning pattern of myositis ossificans. The cartilaginous entities include the true tumors, soft-tissue chondroma and extraskeletal chondrosarcoma, and the tumorlike process, synovial osteochondromatosis. The tumors are relatively rare; synovial osteochondromatosis commonly affects middle-aged men, especially in the knee, and is associated with osteoarthritis. The differential diagnosis for these extraskeletal osseous and cartilaginous lesions includes soft-tissue sarcoma, benign mesenchymoma, malignant mesenchymoma (rare), calcified tophi in gout, melorheostosis (rare), pilomatricoma (rare), and tumoral calcinosis (rare).
四肢的骨外骨和软骨肿瘤及肿瘤样病变通常可通过放射学进行鉴别；对于那些无法鉴别的病变，了解病变谱将有助于进行合理有序的鉴别诊断。在骨病变中——骨化性肌炎、纤维骨性假瘤、进行性骨化性纤维发育不良、软组织骨瘤和骨外骨肉瘤——除骨化性肌炎外，其他均相对罕见。骨化性肌炎具有独特的矿化模式，放射学上可观察到为板层骨的周边边缘。纤维骨性假瘤通常发生于手部手指，且缺乏骨化性肌炎明确的分区模式。软骨性病变包括真正的肿瘤，即软组织软骨瘤和骨外软骨肉瘤，以及肿瘤样病变滑膜骨软骨瘤病。这些肿瘤相对罕见；滑膜骨软骨瘤病通常累及中年男性，尤其是膝关节，且与骨关节炎相关。这些骨外骨和软骨病变的鉴别诊断包括软组织肉瘤、良性间叶瘤、恶性间叶瘤（罕见）、痛风中的钙化痛风石、骨密质增生症（罕见）、毛母质瘤（罕见）和肿瘤性钙化（罕见）。
