Osteoid osteoma is associated with chronic aching pain. A sclerotic ring and central nidus are the characteristic features on X-ray and CT scan. When these are absent, the diagnosis may be delayed. Juxta-articular lesions in particular may lack typical radiological features and delay in diagnosis may be associated with arthropathy, which may initially be reversible. We report the case of an osteoid osteoma of the elbow, which was exceptional in being associated with severe periscapular pain, as well as an exceptional delay in diagnosis. Both the elbow pain and the periscapular pain were temporarily relieved by aspirin and were permanently abolished with ablation of the elbow lesion. We recommend the use of early radioisotope scan and consideration of aspirin sensitivity, in recognising the diagnosis where typical radiological features are not present.
Osteoid osteoma is a well-recognised cause of chronic aching pain. The pain is unrelated to activity and frequently worsens at night. It is typically relieved by nonsteroidal anti-inflammatory drugs and especially by aspirin. This has in the past often been the basis of diagnosis. 
On the X-ray, it is usually associated with a sclerotic appearance, with a radiolucent nidus. Histologically, the nidus is characterised by calcified trabeculae of osteoid and woven bone with an osteoblastic and osteoclastic lining, residing within a richly vascular fibrous stroma. The amount of calcified matrix influences the radiological pattern, which may be purely lytic, mixed lytic and sclerotic or densely sclerotic. Lack of typical radiological features may delay diagnosis.
We report the case of a juxta-articular osteoid osteoma of the proximal ulna, with increasingly severe pain over an eight-year period, which was repeatedly said to be due to arthritis because of degenerative change in the elbow. It was evident that the main problem was in the elbow, as there was increasing pain and stiffness and severe pain on forced movement of the joint. It was, however, unusual in being strongly associated with periscapular pain, which was abolished with the elbow pain following radiofrequency ablation of the elbow lesion.
Case Report Top
The patient initially developed pain in the posterior aspect of the elbow, which gradually became sufficient to disturb sleep over a period of about 18 months. At that time, there was little to see on X-ray, except a suggestion of a semi-loose body on the back of the capitellum. Advice was sought and examination showed pain on sudden extension. There was no limitation of movement at that time. An arthroscopy was advised on the basis of a posterior impingement in the joint and subsequently a debridement was carried out through a posterior arthrotomy.
An initial improvement soon relapsed. Pain became more troublesome over a further two-year period, during which time, there was some loss of full extension and some loss of the last few degrees of flexion. There was severe pain at times if flexion was forced and on the basis of a possible loose body in the front of the elbow, a further arthroscopy was carried out two years after the initial one. Nothing abnormal was demonstrated.
Over the next year, pain worsened, as did loss of elbow movement. A further opinion was sought, as the patient, an orthopaedic consultant, had considered the possibility of osteoid osteoma, having noted sensitivity of the condition to aspirin and diclofenac. A CT scan was carried out which showed a small lucency adjacent to the joint surface of the proximal ulna, adjacent to the coronoid notch. This was said to be a degenerative cyst as there was no sclerosis.
The pain continued to deteriorate and sleep became disturbed on a regular basis. The pain was of a chronic throbbing nature, which increased with time, until further aspirin was taken. At this time, there was a gradually increasing incidence of periscapular pain, which was particularly evident whilst sitting and was frequently the site of the most severe pain causing waking at night (typically after about four hours sleep). The pain was typically felt in the infraspinatus region and generally around the lower half of the scapula, rather than the upper part. There was no shoulder dysfunction whatsoever.
Rapidly increasing hip arthritis then dictated use of diclofenac for some months and the elbow problem became masked. However, following hip resurfacing, diclofenac was discontinued and the elbow and shoulder pain became a prominent and rapidly increasing problem.
By now, the range of movement in the elbow was only 40 to 95°. There was severe pain on forced flexion, tenderness over the medial aspect of the proximal ulna and difficulty completing a full day’s work without regular aspirin. Increasingly, as the pain worsened in between doses of aspirin, the periscapular pain overcame the elbow pain, except when the elbow was jolted.
Because of nightly loss of sleep, typically at about 4am, further advice was sought, three years after the previous CT scan and nine months after the hip surgery. Again, the advice (following X-ray) was that the problem was due to arthritis and a request for a bone scan to be performed was turned down.
After a further six months, a private MR scan was arranged by the patient. This showed abnormal signal in the proximal ulna. A high definition CT scan was advised and then a gadolinium enhanced MR scan. The CT showed enlargement of the lucency seen on the CT four years previously [Figure – 1] and the MR showed enhancing high signal. Accepting the aspirin sensitivity, radiological advice was given that this might indeed be a juxta-articular osteoma, without the normal associated sclerotic ring.
At the specific request of the patient, a radioisotope scan was finally arranged. This showed major uptake of isotope [Figure – 2].
Referral to a specialist radiologist resulted in biopsy and radiofrequency ablation under regional anesthesia. Interestingly, the ablation of the lesion was excruciatingly painful, even after painless drilling through the normal bone under an apparently fully functional interscalene and axillary block. The biopsy confirmed osteoid osteoma. The symptoms of severe elbow pain were abolished within 12 hours and have not recurred at 20 months from ablation. The periscapular pain was abolished at the same time.
Three months following the procedure, the range of movement had improved, to 30 to 110° flexion, but has not improved more after a further year. Symptoms from the elbow joint arthritis are minimal.
When the lesion involves a joint, the diagnosis of osteoid osteoma can be difficult and is often reached only at a late stage. Whilst a sclerotic surround is usual,  this may not be present in immediately juxta-articular positions. In such cases, a diagnosis of simple monoarticular arthritis may be made, with features of joint stiffness, synovitis and local warmth. Lack of typical features means that plain X-rays and even CT scans may miss the correct diagnosis.
In this case, loss of flexion and severity of pain on forced flexion was disproportionate to the loss of extension and to the severity of degenerative disease on X-ray.
Severe and increasing pain at rest is unusual in osteoarthritis and alternative diagnoses should be considered, particularly with severe night pain. Sensitivity to aspirin is highly suspicious of (but not invariable in) osteoid osteoma.  Credence should be given to particular aspirin sensitivity.
There is evidence that osteomas may give rise to degenerative change of the adjacent joint and contracture  which may be reversible if treatment of the osteoma is undertaken at an early stage. It is therefore important to make a diagnosis at as early a stage as possible.
Although radioisotope scan may fail to localise the nidus of osteoid osteoma, this should nevertheless be carried out where any suspicion of an osteoid osteomas exists in relation to a joint, but is not confirmed on other investigations.
The intense periscapular pain was remarkable and caused considerable confusion at times regarding the diagnosis. The lack of additional scapular lesion on isotope scan was reassuring. The abolition of the periscapular pain following the ablation of the elbow lesion seemed almost miraculous.
We have not been able to locate any other case of periscapular pain resulting from an elbow lesion.