Subperiosteal aneurysmal bone cyst with associated bone marrow oedema: An unusual appearance

Multimodality imaging features of USP6-associated neoplasms

Since the discovery of USP6 gene rearrangements in aneurysmal bone cysts nearly 20 years ago, we have come to recognize that there is a family of USP6-driven mesenchymal neoplasms with overlapping clinical, morphologic, and imaging features. This family of neoplasms now includes myositis ossificans, aneurysmal bone cyst, nodular fasciitis, fibroma of tendon sheath, fibro-osseous pseudotumor of digits, and their associated variants. While generally benign and in many cases self-limiting, these lesions may undergo rapid growth, and be confused with malignant bone and soft tissue lesions, both clinically and on imaging. The purpose of this article is to review the imaging characteristics of the spectrum of USP6-driven neoplasms, highlight key features that allow distinction from malignant bone or soft tissue lesions, and discuss the role of imaging and molecular analysis in diagnosis.

Diaphyseal aneurysmal bone cysts (ABCs) of long bones in extremities: Analysis of surgical management and comparison with metaphyseal lesions

INTRODUCTION

Aneurysmal bone cysts (ABCs) are benign lesions of long bone metaphysis affecting mostly medullary region in younger age below 20 years of life. These may be originated rarely either in the cortex or in the superficial regions of diaphysis. The study highlighted the differences of diaphyseal lesions from the usual metaphyseal ones in view of their clinical, radiological and biological behavior and also discussed their management in brief.

MATERIAL AND METHODS

We reviewed a total of 84 aneurysmal bone cysts over the past fourteen years (2004-2017) and evaluated their surgical outcomes retrospectively. Total ten lesions were diaphyseal cortical in location (group I), while 74 lesions were conventional metaphyseal type (group II).

RESULTS

We observed that cortical ABCs were occurred commonly in diaphysis of femur, humerus, tibia and radius while presentation was at an older age than metaphyseal type. Radiographically these were eccentric lesion and more prone for pathological fractures than conventional type. These are differentiated radiographically from other benign lesions but also mimicking malignant conditions including low grade surface osteosarcoma and telangiectatic osteosarcoma while resemble similar to these on histopathological examination (HPE).

CONCLUSION

Biological behavior of cortical lesions does not differ significantly than conventional type but these are more prone for pathological fractures so these eccentric cortical ABC lesions should be treated with adequate internal fixation along with curettage and bone grafting. Although incidence of cortical or surface variety of ABCs is rare but surgeons might evaluate its severity in view of aggressive benign or malignant lesions of diaphysis.

Subperiosteal Aneurysmal Bone Cyst with Florid Ossification: A Rare Subtype

Aneurysmal bone cyst (ABC) is a well-characterized benign cystic lesion of the bone with common localization to the medulla of the long bones. Rarely, ABCs may arise within the subperiosteal region, which can be diagnostically challenging for both the radiologist and pathologist due to their aggressive radiologic appearance thus mimicking other malignant neoplasms. Herein, we present a rare case of subperiosteal ABC with prominent soft tissue involvement and florid reactive periosteal ossification and provide a short literature review on subperiosteal ABCs.

Surface Aneurysmal Bone Cyst: Clinical and Imaging Features in 10 New Cases

Aneurysmal bone cyst originating from the surface of the bone, either within the cortex or subperiosteally, is an uncommon anatomic subtype. This article reports the clinical and radiologic evaluations and treatment outcomes of 10 patients with surface aneurysmal bone cysts that were surgically treated between 1982 and 2014. Mean age at the time of surgery was 22.4 years (range, 11-44 years). According to Capanna's radiographic evaluation criteria, 6 of the lesions were classified as type V and 4 were classified as type IV. Radiographically, periosteal shell formation was observed to be complete in 4 patients, partial in 3, and absent in 3, and 6 patients had Codman's angle or buttress formation. In 1 patient, computed tomography scan showed birdcage-like ossification attached to the surface of bone. Magnetic resonance imaging showed fluid-fluid levels in 5 patients. All of the patients had standard curettage and high-speed burr application as an adjuvant. No patient had local recurrence at the end of the follow-up period of 98.4 months (range, 13-288 months). These findings show the importance of careful radiologic evaluation and biopsy to better plan a treatment strategy when surface aneurysmal bone cyst is included in the differential diagnosis. The finding of fluid-fluid levels on magnetic resonance imaging or computed tomography is not pathognomonic for primary aneurysmal bone cyst; however, the absence of this finding does not rule out the diagnosis. The rate of local recurrence after curettage plus high-speed burr is reasonably low, and other adjuvant procedures should be used whenever needed. [Orthopedics. 2016; 39(5):e897-e903.].

Intracortical chondromyxoid fibroma of the tibia

Intracortical chondromyxoid fibroma is an extremely rare benign neoplasm of cartilaginous origin that usually occurs as an eccentric lesion at the medullar metaphyseal region of long bones. We report the clinicoradiologic aspect of a new case located in the metaphyseal region of the upper tibia and discuss about the differential diagnosis.