Can anyone identify the bone tumor? Treatment?

An 17 year old boy presenting with swelling in lower thigh which was progressively increasing in size, having pain since 10 days.
Discussion:

OSTEOCHONDROMA (EXOSTOSIS) Definition: - Cartilage capped bony projection arising on the external      surface of bone containing a marrow      cavity that is continuous with that of the underlying bone. Epidemiology:  - Most common bone tumor. - Osteochondroma may be solitary or multiple, the latter     occuring in the setting of hereditary multiple exostoses.  - Solitary lesions account for 80% of cases, and most      affected patients are diagnosed in their second decade of      life -     Male preponderance with a male to female ratio 1.5-2:1. - Hereditary multiple exostoses (HME) is an autosomal     dominant genetic disorder , and has prevalence of      1 per 50 000 in the general population making it one of      the more common inherited skeletal disease.  - Patients with HME come to medical attention at the      younger age , usually during first decade, because they      cause severe skeletal deformities and are frequently      polyostic. Sites of involvement:  - Generally arise in bones performed by cartilage.  - Most common site of involvement is the metaphyseal     region of distal femur, uppr humerus, upper tibia and fibula. Clinical findings:  - Many, if not most lesions, are asymptomatic and found    incidentally. In symptomatic cases, the symptoms are     often related to the size and location of the lesion. - Most common presentation is that of a hard of long-     standing duration. Imaging:  - Bulbous lesions on X rays, and they a narrow or broad    (sessile) osseous radiosense stalk, which is attached to      the underlying bone. - The characteristic feature is a projection of the cortex in    continuity with the underlying bone.  - Excessive cartilage type flocullent calcification should     raise the suspicion of malignant transformation.  - CT scan or MRI images typically show continuity of the    marrow space into the lesion. A thick cartilagenous cap     rises suspicion of malignant transformation.Gross:  - May be sessile or pedunculated. - The cortex and medullary cavity extends into the lesion.  - The cartilage cap is usually thin.  - A thick an irregular cap (greater than 2 cm) may be      indicative of malignant transformation. Histopathology:  - Lesion has three layers - perichondrium (fibrous layer     covering cartilage), cartilage and bone.  - Outer layer is a fibrous perichondrium that is continuous      with the periosteum of the underlying bone. - Below this is a cartilage cap that is usually less than 2      cm thick (and decreases with age).  - Within the cartilage cap the superficial chondrocytes are      clustered, whereas the ones close to bone resemble     growth plate.  - Loss of the architecture of cartilage, widefibrous bands,     myxoid change, increased chondrocyte cellularity, mitotic.     activity, significant chondrocyte atypia and necrosis are all     features that may indicate secondary malignant    transformation. Genetics:      -    Abberations involving 8q22-24.1, EXT1 gene. Prognosis:  - Excision is usually curative.  - Recurrence is seen with incomplete removal.