History: A 12-year-old girl without a history of trauma presents with left tibial pain and swelling over the past three weeks.
病史：12岁女孩，无外伤史，左胫骨疼痛、肿胀3周。
Frontal and lateral radiographs of the tibia and fibula are shown below.
胫腓骨正侧位片如下所示。
MRI with and without gadolinium was attained for further evaluation.
进一步行MRI平扫+增强
Findings
Radiographs: Frontal and lateral radiographs of the left tibia and fibula demonstrate a lucent, cortically based lesion in the anterior cortex of the midtibial diaphysis with adjacent sclerosis and cortical thickening. No periosteal reaction or pathologic fracture is present. No soft-tissue component is seen.
MRI: The radiolucent portion of the lesion is well-circumscribed, with homogeneous T1 and T2 hyperintensity, and enhancement on postgadolinium image. No central nidus is present. The adjacent cortex is expanded, but there are no areas of cortical destruction. There is mild adjacent marrow edema, but no medullary extension. No soft-tissue component is present.
Differential diagnosis
Osteofibrous dysplasia
Osteofibrous dysplasia-like adamantinoma
Adamantinoma
Fibrous dysplasia (intracortical)
Diagnosis: Osteofibrous dysplasia
影像表现：
平片：左胫腓骨正侧位片示胫骨骨干中段前部骨皮质内可见一透亮灶，邻近皮质增厚、硬化；未见骨膜反应或者病理性骨折，未见软组织成分。
MRI：病灶的透亮部分边界清楚，T1WI、T2WI均呈均匀高信号，增强扫描明显强化，未见中心瘤巣，邻近骨皮质膨胀，未见骨质破坏区。病变周围轻度骨髓水肿，未见病变向骨髓扩展，未见软组织成分。
鉴别诊断：
骨性纤维结构不良
骨纤维结构不良型釉质上皮瘤
釉质细胞瘤
纤维结构不良（皮质内型）
最后诊断：骨性纤维结构不良
Key points
Osteofibrous dysplasia (OFD)
骨性纤维结构不良
Pathophysiology
Benign, fibro-osseous cortical lesion, most commonly involving the mid-diaphysis of the tibia.
On pathology, composed of woven trabecular bone within a fibrous stroma.
Part of a spectrum of conditions including adamantinomas (more aggressive and has risk of metastasis), and osteofibrous dysplasia-like adamantinoma (OFD/LA).
Idiopathic condition of unknown etiology.
Location:
Tibia is the most commonly involved.
Other sites include the fibula, radius, and ulna.
Natural history:
Benign physiology, but can be locally destructive and result in pathologic fracture.
Growth tends to stabilize, and spontaneous regression occurs once patients become older than 10 years old.
There are high rates of local recurrence after surgery. Some cases of aggressive recurrence were subsequently found to contain components of adamantinoma.
Cases of possible transformation to adamantinoma have been reported, but are very rare.
病理生理学：
骨性纤维结构不良是一种良性的纤维骨皮质病变，最常累及胫骨骨干中段。病理上，主要表现为纤维基质内可见网状松质骨成分。部分报道认为OFD和釉质细胞瘤（更具侵袭性，可转移）、骨纤维结构不良型釉质上皮瘤属于同一类谱系的疾病，部分报道认为OFD为先天性，病因不明。
发病部位：
胫骨最常累及，其它常见部位有腓骨、桡骨和尺骨。
自然病程：
良性肿瘤生理特点，但可见局部骨质破坏，能导致病理性骨折。肿瘤生长较缓慢，一旦患者年龄大于10岁，肿瘤会自行消退并康复。术后的局部复发率较高，一些易复发的侵袭性病变内可发现釉质细胞瘤的成分。有报道称该病可转化为釉质细胞瘤，但非常罕见。
Epidemiology
Majority of patients are younger than 5 years of age at diagnosis (in contrast to adamantinomas, which occur at a mean age of 30 years). There is a male gender predilection.
Clinical presentation
Symptoms:
Pain and swelling
Pathologic fracture, which can progress to pseudoarthrosis
流行病学：大部分患者诊断此病时的年龄小于5岁（釉质细胞瘤平均发病年龄为30岁），男性多见。
临床特点：症状：疼痛、肿胀；病理性骨折，可发展为假性关节。
Imaging features
General:
Differentiation of osteofibrous dysplasia from adamantinoma is difficult on imaging, and histopathology remains necessary for distinction. Osteofibrous dysplasia is usually smaller than adamantinomas.
OFD typically smaller: mean 6-7 cm
Adamantinomas: mean 13 cm
Radiographs:
Intracortical location
Lucent or ground-glass density
Narrow zone of transition with sclerotic margins
Pseudotrabeculations within lesion
No periosteal reaction
Anterior bowing deformity
MRI:
Has homogeneous hyperintensity on T2-weighted images.
Can extend into the medullary cavity, but a large medullary component should raise suspicion for adamantinoma, which often have complete medullary canal involvement.
No soft-tissue component.
No cortical destruction.
影像表现：
一般：骨性纤维结构不良和釉质细胞瘤的影像鉴别非常困难，需要依靠组织病理学；病灶大小上，前者小于后者，典型的骨性纤维结构不良平均大小约6-7cm，釉质细胞瘤平均大小约13cm。
平片：病变位于皮质内，透亮或磨玻璃密度，边缘移行区较窄，可见硬化边，病灶内可见假性骨小梁，无骨膜反应，受累骨向前弯曲畸形。
MRI：T2WI上呈均匀高信号；病变可扩展至骨髓腔内，但骨髓腔内病变较大时需考虑釉质细胞瘤的可能，其多表现为整个骨髓腔受累。病变无明显软组织成分，无骨皮质破坏。
Treatment
Biopsy: Needle biopsy results can be inaccurate in up to 21% of cases.
Surgery is reserved for large size or aggressive behavior.Resection is necessary to reduce recurrence rates (high recurrence rates with curettage and bone grafting).
治疗：活检：细针穿刺活检的病理结果的不准确率高达21%。病变体积较大或有侵袭行为时需手术治疗，手术切除可降低复发率（刮除术及骨移植均有较高的复发率）。
OFD影像图解
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