Aneurysmal bone cyst (ABC)

Bone
Other tumors of bone
Aneurysmal bone cyst (ABC)

Author: Nat Pernick, M.D. (see Authors page)

Revised: 11 July 2017, last major update June 2005

Copyright: (c) 2003-2017, PathologyOutlines.com, Inc.

PubMed search: aneurysmal bone cyst (ABC)

Table of Contents

Cite this page: Aneurysmal bone cyst (ABC). PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/boneabc.html. Accessed July 14th, 2017.

Definition / general

Uncommon; expanding osteolytic lesion of blood filled spaces of variable size separated by connective tissue septa with osteoclast giant cells and variable reactive bone
Usually ages 1 - 20 years, no gender preference
Benign but grows rapidly; simple curettage is followed by recurrence in 20%; rarely transforms to osteosarcoma
Sites: metaphysis of posterior vertebrae (often multiple), flat bones, shaft of long bones; rarely within wall of major artery or in soft tissue (Am J Surg Pathol 2002;26:64, Am J Surg Pathol 1994;18:632, Am J Surg Pathol 1993;17:1062)
May also be secondary to trauma or arise in preexisting bone lesion (giant cell tumor, chondroblastoma, fibrous dysplasia)

Radiology description

Eccentric expansion of bone, cortical erosion and destruction, small peripheral area of periosteal bone formation
Fluid levels detectable by CT
MRI shows honeycomb appearance with fluid levels

Treatment

25% recur after curettage so aggressive curettage with bone grafting or en bloc resection recommended

Gross description

Spongy, hemorrhagic mass covered by thin shell of reactive bone
Small amount of tissue compared to large size of lesion on Xray

Microscopic (histologic) description

Large cystic spaces filled with blood and separated by fibrous septa, alternating with solid areas
Cysts and septa lined by fibroblasts, myofibroblasts and histiocytes but not endothelium
Clusters of osteoclast-like multinucleated giant cells with loose spindly stroma to cellular stroma, reactive woven bone, degenerated calcifying fibromyxoid tissue
Variable mitotic figures and hemosiderin
No malignant osteoid, no atypia

Microscopic (histologic) images

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