A RARE CASE OF PROXIMAL ULNA ANEURYSMAL BONE CYST TREATED WITH FIBULLAR

Received: 07 September 2017 Final Accepted: 09 October 2017 Published: November 2017 An aneurysmal bone cyst (ABC) is a rare,benign, destructive, hemorrhagic and expansile lesion accounting for 1% of all bone tumors with a thin wall containing blood filled cystic cavities. The term aneurysmal is derived from the macroscopic appearance of sponge like tumour containing numerous giant cells. This type of lesion predominantly affects the metaphysis of long bone. The present study reports a rare case of ABC of the proximal ulna occurring in a 16-year-old male patient, who presented with swelling over right elbow joint and pain is the main complain. Xrays and MRI of the left elbow revealed a segmented, expansile, multiseptated lesion with fluid-fluid levels and biopsy was performed initially to confirm the diagnosis followed by enbloc excision of cyst was done and fibular stud graft from right side along with cancellous bone graft from left ASIS (anterior superior iliac spine) and fixed with intramedullary Kwire.The present study aims to describe a case of ABC of the proximal ulna a rare site, a condition that often poses a diagnostic challenge, and to underline the importance of radiological and histological examinations for the accuracy of that diagnosis.


ISSN: 2320-5407
Int. J. Adv. Res. 5 (11), 546-549 547 X-rays showed signs of ballooning of cortex over proximal ulna. Routine blood investigations were normal. MRI was done and differential diagnosis was achieved. The lesion was addressed by posterior approach and curettage biopsy was done. After confirmation of the diagnosis, enbloc excision of cyst was done and fibular stud graft from right side along with cancellous bone graft from left ASIS (anterior superior iliac spine) and fixed with intramedullary K-wire. The elbow was immobilised for 6 weeks followed by gradual passive and active mobilisation The gross appearance of the removed tissue was a soft, dusty-red tissue mass. Histopathological examination was subsequently conducted. The microscopic appearance of the resected tissue was capsule-shaped, exhibiting large amounts of dilatation and congestion of the associated small blood vessels, osteoblast proliferation (as indicated by the blue particles corresponding to osteoprogenitor cells that were detected by hematoxylin-eosin staining), fibrous connective tissue and multinucleated giant cell proliferation, with reactive hyperplasia and trabecular bone tissue. A final diagnosis of ABC was established based on the collective clinical information.
The treatment was successful, as no further treatment was required during subsequent follow-ups. K-wire was removed after 4 months after signs of union on consecutive x-rays.final follow up at the end of 6 months was quite satisfactory with almost full range of movements.
pre op x-ray

Discussion:-
ABCs account for 1% of all primary bone lesions that are sampled for biopsy 13 . While the precise pathogenesis of ABC is unclear, the most widely accepted pathogenic mechanism of ABC involves local circulatory disturbance, which results in an increase in venous pressure and the development of enlarged and dilated vascular components within the affected bone 2 . The differentiation among ABC and other giant cell-containing tumors of the bone, such as GCT, GCRG and Brown tumor, is crucial 13 . GCT is composed of mononuclear and osteoclast-like multinucleated giant cells, which have the potential to be locally aggressive 14,15. In GCT, the tumor is always eccentrically located in the epiphysis and metaphysis of the bone, and exhibits lytic expansion 16 . GCRG is a rare, benign, intraosseous reactive lesion, histologically characterized by a predominance of giant and mononuclear cells in areas of hemorrhage 17 . Brown tumors have been reported to occur in 1.5-1.7% of patients with chronic renal deficiency and to have a considerably more lobulated architectural growth pattern; at differential diagnosis, hyperparathyroidism can be ruled out on the basis of serum calcium, parathyroid and phosphorus hormone levels 18,19. ABC, on the other hand, is known to be histologically composed of blood-filled cystic spaces separated by fibrous septae 20. Computed tomography and MRI scans may be helpful in the diagnosis of ABC, since T2-weighted MRI could detect a deformity in the involved metatarsal bone as a segmented, expansile, multiseptated lesion with a large quantity of fluid present 21. Surgical removal is considered the optimal treatment option for ABC. The lesion is removed by intralesional curettage through a wide cortical window, and bone grafting may be used for replacement of bone defects 22 . Embolotherapy has also been successfully used for the treatment of ABCs 23 . However, patients must be informed that ABC has a high recurrence rate 24 , so that any recurrence or malignant transformation can be detected as early as possible.
In summary, ABC is a destructive, hemorrhagic and tumor-like lesion occurring predominantly in teenaged patients. Radiographs and MRI scans can often confirm the diagnosis of ABC; however, accurate histological evaluation is imperative for diagnosis. Embolotherapy and replacement of bone defects with a autograft are considered safe procedures with minimal recurrence risk 25 . The present study described a rare case of a ABC in prximal ulna and highlighted the importance of radiological and histological examinations for the accuracy of such diagnosis.