概述
Enchondroma is a benign indolent intramedullary hyaline cartilage neoplasm。Accounts for 10% of all benign osseous tumors。Limited growth, most lesions are less than 5 cm in maximal dimension。
一般沒癥狀，除非發生病理性骨折。大約50%發生在手或足上，而這其中大部分發生在指/趾骨上。肱骨及股骨近端是最常見的長骨發病部位。中軸骨（骨盆、脊柱、肋骨）等不常見，但該部位的腫瘤常常具有惡性傾向（軟骨肉瘤）。
分型
Solitary Enchondroma
Multiple Enchondromas (Enchondromatosis/Ollier's Disease)
Maffucci Syndrome (Multiple Enchondromas and Soft Tissue Hemangiomas)
影像學特征
髓腔內生軟骨瘤表現為溶骨性。腫瘤上層皮質骨變薄，一旦出現病理性骨折，皮質骨仍保存完整，也不會出現軟組織腫塊。若皮質骨受到侵蝕或變厚，出現軟組織團塊，往往是內生軟骨瘤惡變的征象。
組織學特征
內生軟骨瘤由分化良好的透明軟骨組成。長骨內生軟骨瘤表現為軟骨細胞減少和無細胞非典型增生，豐富的藍染軟骨樣基質，很少能找到雙核細胞。和內生軟骨瘤相比，手足和骨膜等處的軟骨瘤表現為細胞非典型增生，但仍不能診斷為惡性。在長骨的軟骨瘤，基質粘液樣改變高度提示惡變；但在手足的小塊骨，小幅度基質粘液樣變不能斷定是軟骨肉瘤。惡性腫瘤可以穿透骨小梁，良性腫瘤不會穿透骨小梁破壞皮質骨。
鑒別診斷
The main differential is with a low grade (Grade 1) chondrosarcoma
Can be very difficult to differentiate from a Grade 1 Chondrosarcoma from an enchondroma based on histology
It is easy to differentiate from a grade 2 or 3 chondrosarcoma by means of histology which are hypercellular, pleomorphic and demonstrate mitotic figures
Radiographs and clinical history are important for differentiation
Biopsies are not useful for differentiating an enchondroma from a low grade chondrosarcoma
Features consistent with chondrosarcoma
Pain attributable to lesion
Age greater than 50
Cortical destruction and a soft tissue mass
Periosteal reaction and thickening
Endosteal erosion>2/3 cortical thickness on a CT scan
Size greater than 5 cm
Bone Scan: Lesion that is hotter than ASIS
治療
內生軟骨瘤應行刮除術，必要時骨移植修復骨缺損。如果腫瘤生長活躍或患者感覺疼痛，活檢和刮除術應同時應用。如果刮除干凈，術后腫瘤復發率極低。因為腫瘤很少侵犯皮質骨，所以只需刮除腫瘤即可，有時手術邊界可擴展到周圍1~2mm皮質骨。
Enchondromas are benign, indolent (not growing) tumors
Indications for surgery:Digits: Impending or actual pathological fracture，Intralesional curettage and bone graft or cement；Long bones: Rare to fracturea，usually observe
If grows it is considered chondrosarcoma and would recommend surgery accordingly
預后
Recurrence rate following curettage is <5%。
Recurrence of an enchondroma suggests malignancy。
There are rare cases where enchondromas can dedifferentiate into a chondrosarcoma or dedifferentiated chondrosarcoma (low grade chondrosarcoma with an osteosarcoma, fibrosarcoma or malignant fibrous histiocytoma arising adjacent to it)。
參考文獻：
1、http://www.tumorsurgery.org/
2、王正義 主編《足踝外科學》人民衛生出版社，2006年
