Malignant fibrous histiocytoma at the site of a previously treated aneurysmal bone cyst: a case report

Unusual presentation of an aneurysmal bone cyst: A case report and literature review

Aneurysmal bone cysts (ABCs) are non-neoplastic primary bone tumors, typically involving the long bones and vertebrae in the first 2 decades of life. ABCs require prompt diagnosis and intervention due to their rapidly expansile nature and ability to destroy the adjacent normal bone. ABCs rarely affect the rib. We report a case of a 51-year-old female presenting with chronic dry cough and right upper back pain. A chest X-ray and computed tomography scan revealed an expansile, lytic mass affecting the posterior aspect of the third right rib. The third right rib was resected using a posterolateral, Shaw-Paulson approach. Histopathology of the resected mass confirmed the diagnosis of ABC. There were no intra- or perioperative complications, and follow-up X-ray was normal.

Metachronous aneurysmal bone cyst in a 9-year-old boy: case report and review of the literature

Aneurysmal bone cyst (ABC) is a locally aggressive, benign bone tumor that commonly affects children. Metachronous ABCs are rare, and have been described only three times in the literature. Here we present a fourth case in a 9-year-old boy who presented with an ABC of the scapula; 2½ years later he presented with a tibial ABC. We also review the literature and discuss the pathological and clinical characteristics of this lesion.

Late sarcoma development after curettage and bone grafting of benign bone tumors

BACKGROUND AND AIM

Rarely sarcomas develop in previous benign lesions, after a long term disease free interval. We report the experience on these rare cases observed at a single Institution.

PATIENTS AND METHODS

12 cases curetted and grafted, without radiotherapy developed sarcomas, between 1970 and 2005, 6.5-28 years from curettage (median 18, average 19). Age ranged from 13 to 55 years (median 30, average 32) at first diagnosis; tumors were located in the extremities (9 GCT, benign fibrous histiocytoma, ABC, and solitary bone cyst). Radiographic and clinic documentation, for the benign and malignant lesions, were available. Histology was available for 7 benign and all malignant lesions.

RESULTS

To fill cavities, autogenous bone was used in 4 cases, allograft in 2, allograft and tricalcium-phosphate/hydroxyapatite in 1, autogenous/allograft in 1, heterogenous in 1. For 3 cases the origin was not reported. Secondary sarcomas, all high grade, were 8 osteosarcoma, 3 malignant fibrous histiocytoma, and 1 fibrosarcoma.

CONCLUSIONS

Recurrences with progression from benign tumors are possible, but the very long intervals here reported suggest a different cancerogenesis for these sarcomas. This condition is extremely rare accounting for only 0.26% of all malignant bone sarcomas treated in the years 1970-2005 and represents only 8.76% of all secondary bone sarcomas treated in the same years. This incidence is the same as that of sarcomas arising on fibrous dysplasia, and is lower than those arising on bone infarcts or on Paget's disease. This possible event must be considered during follow-up of benign lesions.

Imaging findings, prevalence and outcome of de novo and secondary malignant fibrous histiocytoma of bone

OBJECTIVE

To evaluate the radiographic and magnetic resonance (MR) imaging features of primary and secondary malignant fibrous histiocytoma in bone and determine the demographics, prevalence and outcome of patients with this tumor.

MATERIALS AND METHODS

A retrospective search of files from two institutions identified 28 patients with malignant fibrous histiocytoma (MFH) of bone. Microscope slides were reviewed to confirm diagnosis and identify any pre-existing lesions. Medical records were reviewed with respect to patients' demographic characteristics and outcomes.

RESULTS

Radiographic features demonstrated an aggressive osteolytic lesion with a permeative pattern of bone destruction. Periosteal reaction was seen in three of 13 lesions. T1-weighted images (T1WIs) demonstrated signal intensity iso- to slightly hyperintense to muscle. T2-weighted images (T2WIs) demonstrated mildly higher signal intensity than that of muscle. The 5-year survival rate was 53%. The tumor arose secondarily in pre-existing lesions in 43% of patients. Metastases occurred in 46% of patients during the course of the disease, with pulmonary and osseous metastases being the most common.

CONCLUSION

Secondary MFH of bone was slightly less common than primary MFH and had a prognosis similar to that of primary MFH of bone. MR imaging showed variable and somewhat unusual low to intermediate T2 signal characteristics for a radiographically malignant osteolytic lesion.

[Aneurysmatic bone cyst coexisting with osteosarcoma. Radiopathologic discussion]

Aneurysmatic bone cysts are benign lesions of unknown origin. It has been postulated that they might occur in reaction to trauma or to a primary benign (giant cell tumor, chondroblastoma, etc.) or malignant (osteosarcoma) bone tumor that results in local hemodynamic changes. Their malignant transformation is controversial. We present a case of low grade osteosarcoma with a radiologic progression that was indistinguishable from that of an aneurysmatic bone cyst.

Case reports: malignant transformation of aneurysmal bone cysts

An aneurysmal bone cyst is an uncommon benign primary bone tumor. Careful intralesional curettage through a wide cortical window in addition to cauterization with or without adjuvant therapy (phenol or hydrogen peroxide) and bone grafting or cementation is the preferred surgical treatment. Adjuvant or primary radiation of an aneurysmal bone cyst rarely is used because of its association with malignant transformation of the lesion. Several cases of late malignant transformation of primary aneurysmal bone cysts without adjuvant radiation have been reported. We provide additional documentation of two primary aneurysmal bone cysts treated surgically with careful intralesional curettage through a wide cortical window and allograft bone grafting without adjuvant radiation. At 5.5 years and 12 years after treatment, a telangiectatic osteosarcoma and a fibroblastic osteosarcoma, respectively, were identified in the site of the original lesions. Not only should aneurysmal bone cysts be evaluated carefully through histologic examination at presentation, patients also should be counseled regarding possible recurrence and the need for routine followups, especially if symptoms change.