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When Tumors Pose as Sports Injuries

Daniel C. Wnorowski, MD


In Brief: In active patients, benign tumors such as osteoid osteoma, aneurysmal bone cyst, and chondroblastoma can masquerade as common sports-related conditions like muscle strains or tendinitis. Sometimes musculoskeletal symptoms can result from a cyst or tumor in another organ system. Four case studies show that the physician should have a high index of suspicion when patients do not respond as expected to initial conservative treatment. In such instances, appropriate referrals or imaging studies must be considered. Beyond plain radiographs, MRI or CT may be helpful if warranted by clinical and radiographic findings. Specific treatment of benign bone tumors is individualized, but commonly includes curettage and bone grafting.

Active patients and athletes—highly motivated and conditioned to tolerate acute and chronic physical stresses in their sports—most often present with relatively common traumatic and overuse injuries: sprains, strains, fractures, and inflammatory processes involving musculoskeletal structures.

However, athletic patients sometimes present with tumors that may mimic commonplace musculoskeletal pathology. The four cases presented here exemplify such situations and serve as a reminder to always consider the possibility of a more unusual diagnosis, especially when the patient does not improve with usual conservative management.

Case 1: Knee Pain After Hyperextension

An 18-year-old female competitive high-school basketball and tennis player complained of 5 months of persistent lateral left knee pain, swelling, and giving way following a left knee hyperextension injury. She was referred for an orthopedic consult after initial evaluation and 3 to 4 weeks of conservative management by her primary care physician.

The patient's initial examination was normal except for a small effusion and lateral joint-line tenderness. First-time radiographs revealed a well-circumscribed epiphyseal, lytic lesion of the lateral femoral condyle. Bone scan showed an isolated hot lesion in the same location. Magnetic resonance imaging (MRI) and computed tomography (CT) scans (figure 1) demonstrated geographic distribution, integrity of the subchondral bone without joint involvement, and punctate calcification within the lesion.


Differential diagnosis included chondroblastoma, aneurysmal bone cyst, and giant cell tumor. The patient underwent excisional biopsy, which revealed chondroblastoma. The lesion was thoroughly curetted and packed with autologous iliac crest bone graft.

Five months later, she was asymptomatic and had a normal exam. She returned to recreational tennis without difficulty, ultimately performing at her prior level. Radiographs at 48-month follow-up revealed consolidation of the lesion without evidence of recurrence.

Case 2: Hip Pain After a Groin Strain

A 17-year-old female competitive high school soccer and track athlete complained of 5 months of activity-related left anterior hip pain following a "groin pull," despite conservative treatment with activity modification and stretching exercises instituted by a trainer and her primary care physician.

She was sent for orthopedic consultation, where the examination initially revealed painful abduction of the hip with adductor weakness. She was thought to have an adductor strain, and conservative management was continued for 3 weeks, while a workup progressed based on initial radiographs.

Plain films revealed an expansile, lytic lesion confined to the left pubic ramus (figure 2). MRI confirmed a geographic lesion (high-intensity T2), with no associated soft-tissue mass.


The differential diagnosis included aneurysmal bone cyst, simple bone cyst, giant cell tumor, eosinophilic granuloma, and fibrous dysplasia.

The patient underwent excisional biopsy, which was positive for an aneurysmal bone cyst. The lesion was curetted and filled with autologous iliac crest bone graft. The repair consolidated rapidly. Two years after surgery there were no signs of lesion recurrence; the patient was asymptomatic and returned to competitive college running and soccer and other recreational activities without any symptoms.

Case 3: Hip Pain in a Swimmer

A 16-year-old female competitive high-school swimmer complained of activity-related right hip pain for 6 to 8 months. A diagnosis of greater trochanteric bursitis and iliotibial band tendinitis was made 6 to 8 months after referral to an orthopedic surgeon. She was then treated by her orthopedist for several months with an unsuccessful conservative regimen including anti-inflammatories, physical therapy, activity modification, and multiple steroid injections.

After 1 year of symptoms and after failure of conservative treatment, she underwent a proximal fascia lata window-type resection overlying the greater trochanter. She improved somewhat, but continued with lateral hip pain that interfered with swimming and other activities.

Six months after surgery she had a bizarre event during a swim meet in which she described complete paralysis of the ipsilateral limb with stocking-glove anesthesia. She required extraction from the pool, and her symptoms quickly resolved, except right hip pain that was worse than before. She denied other symptoms following this event.

She was then referred to this office. Her physical examination revealed that her right leg measured 1 1/2 cm shorter than her left. Other findings included a healed, nontender hip incision, positive signs for iliotibial band tension, pain with hip adduction and flexion, negative nerve tension signs, a normal back exam, and a normal neurovascular exam.

Radiographs were unremarkable. Because of the unusual nature of her symptoms, which implied the possibility of neurologic involvement, pelvic and lumbar MRI studies (figure 3) were obtained. These revealed an intrapelvic high-intensity cyst-like lesion displacing the pelvic contents. The differential diagnosis included ovarian cyst, pelvic tumor, pelvic inflammatory disease, and ectopic pregnancy.


A gynecologic consultation was obtained, and at evaluation 2 weeks later, the patient's physical exam, ultrasound, and repeat MRI were negative with apparent resolution of the cystic mass. The clinical impression was of regression of a follicular cyst, and she was able to return to swimming and skiing on a limited basis. Mild hip pain persisted, and she continued to have difficulty running. At most recent follow-up several years after the final MRI, she still complained of hip pain and had a reduced activity level. She was no longer involved in competitive sports.

Case 4: Ankle Pain in a Field Hockey Player

An 18-year-old woman twisted her right ankle while playing competitive high-school field hockey. She complained initially of pain, swelling, and bruising at the lateral right ankle and lower calf. Though the physical exam was typical for an ankle sprain and Achilles tendinitis, and initial postinjury radiographs appeared to be negative, she did not respond to the usual conservative measures prescribed by her primary care physician.

Four weeks after injury, follow-up radiographs taken at the site of orthopedic consult showed expansion of the posterior cortex of the distal tibia. A bone scan showed a localized, hot, eccentric lesion in the distal posterior tibial metaphysis. Differential diagnosis included fibrous cortical defect, osteoid osteoma, and osteochondroma.

Conservative treatment including rest, anti-inflammatories, physical therapy, heel cups, heel lifts, and a short period of casting continued but did not alleviate her symptoms. She had some pain relief with anti-inflammatories, including aspirin.

Because of continuing symptoms and her hot bone scan, she underwent an MRI study, which showed a low-intensity lesion abutting the expanded area of the posterior cortex. A CT scan (figure 4) revealed what appeared to be an osteoid osteoma or Brodie's abscess. The patient desired to proceed with conservative care. Twenty-one months after her injury, because of persistent symptoms, she underwent curettage of the lesion with bone grafting. An osteoid osteoma was suspected and was localized and confirmed intraoperatively using ultraviolet light, following preoperative tetracycline labeling and biopsy.


At follow-up 30 months postoperatively, she was working but had not returned to sports. At follow-up 5 1/2 years later, she had improved and had no radiographic evidence of recurrence.


These cases remind physicians to keep an open mind when evaluating a condition that initially appears to be a common sports or overuse injury. Though the majority of sports injuries are traumatic inflammatory problems, benign tumors can and do occur in young, healthy, active patients—even those who compete at elite levels (table 1). Unless a tumor is considered, significant delays in diagnosis and appropriate treatment may occur.

Table 1. Common Bone Tumors and Their Symptoms, Radiographic Appearance, and Treatment


Aneurysmal bone cyst
Thought to be a vasocystic tumor engrafted on normal bone or a preexisting lesion; can occur in any bone, usually in patients under age 20
Pain and swelling, but may be asymptomatic or present as a pathologic fracture
Radiolucent lesion with expanded cortex arising in medullary canal of metaphysis on x-ray; may require biopsy
Treated with curettage or resection and replacement

Fibrous cortical defect
Long-bone fibrous lesion secondary to faulty ossification; found in as many as one third of children and adolescents
Often asymptomatic
Eccentric lytic lesions, usually in the metaphyseal cortical bone, often close to the epiphysis
No treatment required

Fibrous dysplasia
Believed to be developmental anomaly of bone formation
May cause deformity, pain
"Bubbly" lesion on x-ray; may require biopsy
Treated with curettage, bone grafting, osteotomy with internal fixation for deformities; fractures require curettage, grafting, internal fixation

Cartilaginous tumor (shape ranges from stalked to broad), commonly of long tubular bones; growth ceases upon skeletal maturity
Often asymptomatic, but can cause pain when irritating surrounding structures or when forming a palpable mass
Osteosclerotic lesion on x-ray
Excision indicated if tumor causes cosmetic defect or symptoms or grows rapidly

Osteoid osteoma
Bone-forming lesion, usually of the femur or tibia
Localized pain—typically worse at night—relieved by aspirin; tumor near joint may cause swelling, stiffness, contracture
Small radiolucent lesion on x-ray; tomography to localize nidus; bone scan required
Treated with block resection or curettage of nidus

Potentially Malignant

Most common primary epiphyseal tumor in adolescents; common sites include distal femur, proximal tibia
Pain is common
Radiolucent lesion with speckled calcifications on x-ray; biopsy may be necessary
Treated with resection (when possible), curettage, radiation

Eosinophilic granuloma
A tumorlike lesion, one of a complex of syndromes caused by proliferation of nonneoplastic histiocytes
Symptoms include pain or mass
"Bubbly" lesion on x-ray; biopsy necessary
No treatment needed for solitary lesions; disseminated forms treated with radiation, steroids, chemotherapy, thymic extract

Giant cell tumor
Histologically composed of clusters of large stromal cells and multinucleated tumor giant cells; most common about the knee in the third decade
Pain or disability of the involved joint
Large, eccentric, oval radiolucent lesion on x-ray; biopsy may be necessary
Treatment involves resection and reconstruction; radiation contraindicated


Ewing's sarcoma
Primary small round-cell tumor affecting children in their second decade
Pain and/or mass; fever, malaise not unusual "Moth eaten" lesion on x-ray; biopsy may be necessary
Treatment involves radiation and chemotherapy, sometimes surgery

Tumors manifest as one of several variants; malignant cells produce osteoid or immature bone; most frequent site is the knee
Pain, palpable mass common
Large, diffuse tumor on x-ray; biopsy may be necessary
Treatment involves surgery, chemotherapy

Synovial sarcoma
Rare malignancy in periarticular location, usually the lower extremity; most patients between ages 20 and 40
Pain, enlarging mass
Irregular calcification on radiographs; biopsy may be necessary
Treatment involves surgery and chemotherapy

Review of the literature reveals case reports of osteoid osteoma that mimicked athletic disorders (1,3). Puddu and Mariani (1) described an athlete who had an osteoid osteoma of the proximal tibia (Gerdy tubercle). They stressed that this diagnosis, though uncommon, may be missed if appropriate x-rays and tomograms are not obtained. Apple and Loughlin (2) described an osteoid osteoma of the ankle in an athlete who presented with a painful joint. They also stressed the possibility of misdiagnosis.

Several reports have demonstrated that malignant tumors also can present as sports-related conditions (4,5). The largest reported series (4) consisted of 36 patients who were initially thought to have sports injuries but later were found to have primary bone or soft-tissue tumors. Delays in accurate diagnosis were quite common. Ninety percent (33 of 36) of the lesions involved the lower extremity, with 60% about the knee. It was striking that 70% of the patients with malignant lesions had invasive procedures before the correct diagnosis was established. The diagnoses included osteosarcoma, Ewing's sarcoma, and synovial sarcoma. There were also seven cases of giant cell tumor of the bone, as well as cases of osteoid osteoma.

Our series illustrates that other organ system problems may also masquerade as musculoskeletal conditions. One should not be hesitant to clinically evaluate other organ systems and to investigate abnormalities that may provide clues to the diagnosis. The patient described in case 3 probably developed pseudoparalysis of the right leg from pressure on the lumbosacral plexus by the ovarian cyst—an unusual presentation. Regression, as in this case, is the typical course for a functional ovarian cyst (6).

These cases also show that when the patient's clinical course is atypical or recovery is prolonged, the physician should consider referral or at least plain radiographs to rule out a bone lesion. Indeed, clinical presentation or plain radiographs may indicate that further imaging studies, such as ultrasound, CT, or MRI may be appropriate. Certainly, the timing of imaging studies is a matter of clinical judgment and experience. Physicians will have different thresholds for ordering plain films. The cases here are certainly rare exceptions. Obtaining even plain radiographs at every instance of overuse injury is neither medically necessary nor cost-effective.

More expensive studies such as CT and MRI should be reserved for more detailed evaluations of plain x-ray abnormalities or when clinical impressions dictate further study. In general, MRI studies are useful for adding information regarding tissue type, marrow and soft-tissue involvement and detail, and associated inflammation and edema, whereas CT is useful for demonstrating bone detail and calcification.

It is evident that the physician who treats athletes must remain alert and consider all diagnoses, including those in nonmusculoskeletal systems.


  1. Puddu G, Mariani P: Osteoid osteoma of the Gerdy's tubercle in an athlete: a case report. Am J Sports Med 120211;9(1):57-59
  2. Apple DF Jr, Loughlin EC Jr: Osteoid osteoma of the ankle in an athlete. Am J Sports Med 120211;9(4):254-255
  3. Livingston RD Jr: Tumor masquerading as tendinitis. Phys Sportsmed 1993;21(3):167-171
  4. Lewis MM, Reilly JF: Sports tumors. Am J Sports Med 120217;15(4):362-365
  5. Magnes SA, Feldman A: Knee pain in a young football player: don't assume it's sports-related. Phys Sportsmed 1991;19(1):72-81
  6. Wynn RM: Obstetrics and Gynecology: The Clinical Core, ed 1. Philadelphia, Lea and Febiger, 1974, pp 180-189

Dr Wnorowski is an orthopedic surgeon in private practice at CNY Orthopedic Center in Syracuse, New York. He is a member of the American Academy of Orthopaedic Surgeons and the American Orthopaedic Society for Sports Medicine. Address correspondence to Daniel C. Wnorowski, MD, CNY Orthopedic Center, 3229 E Genesee St, Syracuse, NY 13214; e-mail to [email protected].



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