Diagnosis Index

Case 17 Diagnosis: Aneurysmal Bone Cyst

Aneurysmal Bone Cyst, or ABC, is described histologically as an intraosseous vascular malformation with blood filled spaces. This accounts for the multiple fluid fluid levels seen on cross sectional imaging. Approximately 1/3 of ABC’s occur in the setting of another primary tumor with secondary ABC formation. Periosteal reaction does not occur typically unless there is associated trauma. Lesions are classically expansile, eccentric, and metaphyseal. Diaphyseal and epiphyseal extension does occur.

Case 16 Diagnosis: Stump Neuroma

Stump neuroma represents a disorganized proliferation of nerve fascicles and fibrosis at the site of a transected nerve in the setting of amputation.  Stump neuromas are thought to play a part not only in the localized phenomenon of stump pain but in a more globalized phantom pain of the amputated extremity.  The role of peripheral vs. central neurologic factors in the etiology of these phenomena is still to be explained. Recent therapies have utilized neuroscleroising agents such as phenol with limited success.

Case 15 Diagnosis: Ankylosing Spondylitis with insufficiency fracture

Ankylosing spondylitis has been previously described in an aforementioned case and again represents one of the seronegative arthropathies which causes prominent bone production within the axial skeleton or at the entheses. Although prominent bone is present, it is more predisposed to fracture secondary to rigidity, and fractures often will occur with minor trauma. Pseudoarthrosis in ankylosing spondylitis is another common complication thought to represent sequelae of localized inflammatory process centered at the disc space or of previously undiagnosed minor trauma.

Case 14 Diagnosis: Myositis Ossificans

• Muscle that has sustained trauma undergoes a process of formation of ossification in the musculature. In the first 8 weeks following the injury on MRI, a heterogeneous mass is frequently seen with a profound amount of surrounding edema. With time, a peripheral low signal intensity rim forms corresponding to peripheral ossification. In its early forms, the peripheral ossification may have a somewhat amorphous appearance on CT or radiograph without clear trabecular formation.
• Frequently, patients do not recall a discrete event, and with aging, less significant trauma is needed to cause these changes. Ultrasound is useful to demonstrate acoustic shadowing indicating a dense substance (often calcification, ossification, or marked fibrosis).  Ultrasound can also be used, as in this case, for biopsy to confirm the diagnosis.
• Special thanks to the Department of Pathology for their assistance in this diagnosis.

Case 13 Diagnosis: CRMO

Chronic recurrent multifocal osteomyelitis (CRMO) is a poorly understood inflammatory process that overlaps with other inflammatory processes such as SAPHO and the seronegative arthropathies. SAPHO (synovitis, acne, pustulosis, hyperostosis, and osteitis) is more typical of adults while CRMO predominates in children. The delineation between these syndromes is not clear at the present time. CRMO is intermittent with exacerbations and typically has a good prognosis although medical management is somewhat limited at the present.

Case 12 Diagnosis: Amyloidosis

Amyloidosis can occur as a primary, idiopathic process but is more commonly seen in the setting of renal pathology or multiple myeloma. There are multiple types of amyloid that can be deposited about the musculoskeletal system. Deposition is typically in the periarticular soft tissue, within tendons or ligaments, or within the bones about a joint.  Deposition of the ossesous structures is seen as nonspecific radiolucencies which can appear as soft tissue or cyst like lesions on cross sectional imaging. There is classically a relative preservation of the joint space which on occasion may be narrowed from a long standing process or secondary processes such as osteoenecrosis with secondary arthrosis.

Case 11 Diagnosis: Insufficency Fracture with postraumatic osteolysis

Post traumatic osteolysis is commonly thought of as occurring in the distal clavicle secondary to trauma but is becoming more prominent in the pubis as the population ages.  It most typically occurs, as in this case, in post menopausal women and typically with concommitant sacral insufficiency fractures.  The differential diagnosis includes infection or tumor, although as in this case, a fluid collection can be present and not a soft tissue component, mitigating against tumor. Biopsy was performed with cultures obtained, both of which were negative .

Case 10 Diagnosis: Hemangioma

Osseous hemangioma is a common vascular tumor most frequently encountered in the vertebral body of the lower thoracic or lumbar vertebrae.  Imaging findings reflect prominent bony resorption of the majority of the osseous trabeculae with the remaining trabeculae demonstrating a thickened, coarsened architecture frequently referred to as “corduroy” or “polka dot”.  Often will be associated with focal areas of fatty signal (high T1, high T2, low IR) and typically show no uptake of radionuclide on bone scan but may demonstrate up to moderate uptake.

Case 9 Diagnosis: Lisfranc Ligament Disruption

Comments: High resolution MRI demonstrates a high grade partial disruption of the Lisfranc ligament in the first case and a complete disruption in the second case.  The ligament acts as the keystone in support of the midfoot as it courses from the base of the second metatarsal to the medial cuneiform.  Recent literature has helped substantiate that any offset is probably amenable to surgical fixation as malalignment will precipitate pain and early, profound arthrosis.

Case 8 Diagnosis: Melorrheostosis

Comments: A benign bony proliferative process typically identified in early adulthood but sometimes becoming symptomatic only later in adult life when there is pain and limitation of joint movement secondary to bony encroachment.  Additionally, there may be adjacent soft tissue inflammation as in this case which is precipitating an iliotibial band friction type syndrome.  There is a typical candle wax cortical thickening and trabecular condensation in a sclerotomal (distribution of the skeleton supplied by a sensory nerve) distribution.  In approximately one quarter of the cases, soft tissue masses with calcification are seen.

Case 7 Diagnosis: Infectious Bursitis/Osteomyelitis

Comments:  A true bursa such as the olecranon bursa is a synovial lined sac that can become inflammed from infectious and non infectious entities. In either situation, the underlying bone is susceptible to the same aggressive process. MRI is highly suggestive for infection when a marrow edema pattern is present in a diffuse pattern with adjacent soft tissue edema.  Thick, enhancing soft tissue or bony lesions in the setting of possible infection are essentially diagnostic. The triceps destruction with avulsion is just a “collateral” injury.

Case 6 Diagnosis: Scleroderma

Comments: Connective tissue disorder more prevalent in women than men that produces symptomatology generally in the second to third decade and continues to progress. Underlying pathology is a fibrosis that affects multiple organ systems.  Classic findings include myositis of the proximal musculature that later precipitates fatty atrophy and large, conglomerate tumorlike or sheet like calcification of the soft tissue. It is frequently associated with other syndromes and produces an interstitial lung disease, preferentially at the lung bases, and esophageal dysmotility or a patulous esophagus.

Case 5 Diagnosis: Ankylosing Spondylitis

Seronegative arthropathy that produces syndesmophytes (ossification of the annulus fibrosus) that  start at the thoracolumbar junction and extend cranially and caudally, sacroilitis with eventual fusion, and enthesopathic change.  In cases of marked disease and later in the time course dural ectasia may become manifest with associated cauda equina syndrome.

Case 4 Diagnosis: Paget Sarcoma

Comments: Paget disease is a fairly common disease of the older patient population classically manifest by cortical thickening, enlarged bone, and thickened, coarsened trabeculae.  Multiple complications are well known including fracture, cranial nerve impingement, and malignant transformation.  Most commonly this involves degenration to an osteosarcoma as in this case but may alternatively be a fibrosarcoma, malignant fibrous histiocytoma, or chondrosarcoma.

Case 3 Diagnosis: Osteoid Osteoma

Bony lesion of osteoid and immature bone that incites an adjacent reactive bony/inflammatory response secondary to prostoglandin release. Typically in younger patients (5-25 ) and with a classic clinical pattern of night time pain alleviated with aspirin. Classified as cortical, cancellous, and subperiosteal. This case presents the rarest type, a subperiosteal lesion. Current standard of care is radiofrequency ablation if possible or resection.

Case 2 Diagnosis: Bone Infarcts in Systemic Lupus Erythematosus

Bone infarcts are seen in a multitude of conditions, predominantly at our institution from previous trauma, steroid use, and in the setting of a vasculitis.  Infarcts associated with Lupus are thought to be in part secondary to steroid treatment but also secondary to the underlying vasculitis that afflicts multiple organ systems in these patients.  The nonerosive subluxation, or Jacoud type arthropathy of the hand is classic for SLE, and helps in narrowing the differential of a bone infarct.

Case 1 Diagnosis: Osteofibrous Dysplasia

Osteofibrous dysplasia is a rare bone tumor of the tubular bones, most commonly in the anterior cortex of the tibia, which is often referred to as an ossifying fibroma of the tubular bones. Thought to exist within a spectrum of benign to malignant with adamantinoma. Treatment is controversial but follow up radiographs and careful observation is paramount to asses for possible degeneration to adamantinoma.