A 17 year-old woman applied with the complaints of swelling and pain in her left knee. She had been having a lump in the region for years; but pain had started later, as the lump grew bigger. She also complained from cosmetic disturbance.
Our case is a 17 year-old young woman. She came to our hospital with pain in her left knee. There was also a swelling at the lateral aspect of her left knee joint. She gave a history of years for this swelling. But pain had started recently, as the lesion grew bigger. The growth of the lesion had led to a bulky appearance at the site; and she was also complaining from cosmetic disturbance. Her X-rays were obtained; and they showed an expansile bony mass at the fibular head. The mass was in continuity with the host bone. The transitional zone was sharp and clear-cut. General appearance of the lesion gave a benign impression; in fact the pattern was typical for an osteochondroma or, exostosis. The patient was also examined by magnetic resonance imaging (MR), for a better and detailed viewing. The T1-weighted images clearly outlined the lesion borders, which were sharp, and again, in full continuity with the fibular contours. There was slight enhancement of the lesion after gadolinium administration. No malignant signs, such as aggressive destruction and massive contrast uptake, were encountered. The diagnosis of a solitary osteochondroma was made. The patient was operated, mainly due to the clinical problems of pain and cosmetic disturbance. Pain was due to the impression effects of the mass on nerves and vessels nearby. The lesion was excised; and the pathology result came as osteochondroma. She is now in very well condition, physically and psychologically.
Solitary osteochondroma, or osteocartilaginous exostosis, is a hyperplastic/dysplastic bone disturbance originating from displaced or aberrant cartilage of the growth plate. There is a developmental osseous anomaly resulting in exophytic outgrowth on surface of bone.Growth ends when nearest epiphseal plate fuses. Solitary osteochondroma is the most common benign growth of the skeleton; and it constitutes 45% of all benign tumors and 12% of all bone tumors . It is most frequently seen between the first and third decades; and the male:female ratio is 1:1. But this ratio is reported as 1.8-2.1 in some different sources . The mass itself is usually painless, and present for many years. But there may be pain with impingement on nerves and blood vessels. Bursitis may form over cap. Pain in the absence of fracture, nerve compression, or bursitis is considered malignant until proven otherwise. Osteochondroma is usually a benign lesion with self-limited growth. Malignant transformation may ocuur in 1-2% of solitary lesions. Gd enhanced MR examination may help in the differentiation of a malignant outgrowth by depicting aggressive contrast uptake by the tumor tissue. The radical method of therapy for the lesion is surgical resection. If the entire cartilage cap is removed, recurrence is unlikely (<5%).The common sites of the tumor are the long bone metaphyses of the femur, humerus, proximal radius, tibia (50%about knee); scapula; rib; pelvis; and spine (1-5% commonly thoracic). But it may be encountered in any bone that develops by enchondral calcification. There are mainly two types of the tumor: a) pedunculated form, b) broad-based form. The cartilage may ossify or calcify. As for the microscopic features, there is a cartilage cap containing a basal surface with enchondral ossification. There may be a bursa at the periphery of some osteochondromas, attached to the perichondrium of the cap. The bursa wall is usually lined by synovium. The best diagnostic clue is the presence of an exostosis with continuity of bone cortex and medullary marrow space to host bone. There is a cartilage-covered bony projection (exostosis) on the external surface of the bone. The hyaline cartilage cap is usually calcified. In the pedunculated type, slender pedicle is directed away from the joint; and the lesion grows at right angles to the long axis of the host bone. In the sessile type, there is a broad-based attachment to the cortex. In some osteochondromas, there may be undertubulation of long bones (Erlenmayer flask deformity). Main signs of malignant deformation are the development of thick and bulky cartilaginous cap (thickness>1 cm), the presence of dispersed calcifications within cartilaginous cap, and the development of a soft tissue mass. Parosteal osteosarcoma, periosteal chondroma, chondrosarcoma, juxtacortical myositis osssificans, and subungual exostosis are the main entities in the differential diagnosis list.
Solitary Osteochondroma (Exostosis) of The Fibular Head
A noticeable bony protrusion is seen in the proximal tibia of the patient’s left knee. X-ray images show that both the cortical and medullary portions of the lesion are continuous with the parent bone (tibia). The lesion exhibits exophytic growth, with an oval or irregular shape and a cartilaginous shell. There is no significant evidence of bone destruction. On MRI, the lesion’s marrow space is in continuity with the tibia’s medullary cavity; its T1 signal is comparable to normal bone, and T2 images reveal relatively high signal intensity in the cartilaginous cap, where there may be localized calcification. No obvious swelling or invasion is noted in the surrounding soft tissue, and there are no clear signs of neurovascular bundle compression.
Overall, the lesion presents with typical bone outgrowth imaging findings. It maintains continuity with the host bone and is consistent with common features of a bony outgrowth (osteochondroma).
Considering the patient’s age, typical exophytic bony protrusion imaging, continuity of the medullary cavity with the parent bone, and a visible cartilaginous cap on imaging, the most likely diagnosis is:
Solitary Osteochondroma.
If further imaging or clinical assessments (such as cartilage cap thickness, lesion growth rate, or local persistent pain) raise concerns about malignant transformation, contrast-enhanced MRI or biopsy should be considered to rule out chondrosarcoma or other malignancies.
Because the patient reports enlargement of the lesion, associated pain, and cosmetic concerns, surgical resection can be considered, especially if there is suspicion of malignant change, neurovascular compression, or functional impairment. In surgery, the bony protrusion and cartilaginous cap should be removed completely to reduce the chance of recurrence.
If the lesion is relatively stable, pain is not significant, or it only causes minor interference, periodic follow-up may be sufficient to monitor changes in lesion size and the thickness of the cartilaginous cap.
The rehabilitation process after surgery or during conservative treatment can be divided into the following phases:
Throughout the rehabilitation process, an individualized approach should be adopted, adapting to the patient’s pain levels or functional status to prevent overuse injuries.
Disclaimer: This report is a reference analysis based on the existing imaging and medical history. It is not a substitute for an in-person consultation or professional medical advice. Actual treatment and rehabilitation plans should be made in consideration of the patient’s overall condition, the surgeon’s expertise, and further test results.
Solitary Osteochondroma (Exostosis) of The Fibular Head
