Rare aneurysmal bone cysts: multifocal, extraosseous, and surface variants

Abstract

Multifocal, extraosseous, and surface aneurysmal bone cysts are rare variants of the primary lesions. The clinicopathological features are similar, and the optimal treatment is surgical. Although local recurrences may occur, the prognosis is excellent. This review article introduces the readers to a rare diagnosis which they may have been previously unfamiliar with, presents the clinicopathological and imaging features of these rare aneurysmal bone cyst variants, and discusses their diagnosis and treatment. The clinicians who treat patients with aneurysmal bone cysts should be familiar with these uncommon entities and their differential diagnosis.

Multifocal Polyostotic Aneurysmal Bone Cyst of Pelvic Bones

“…This variant seems to be particularly frequent in male patients (5 patients/7 in Angelini A et al's review), and the most reported sites are the femur and the tibia [8]. No case of multifocal ABC of pelvic bones was found.The multifocal forms of ABC are in the majority of cases described metachronously [5,6,8,[13][14][15], the synchronous occurrence in the same patient is exceptional. Only one case of two separate synchronous ABC of the humerus was found in Mohaidat ZM et al series [9].…”

“…There are two types of multifocal ABC: mono-ostotic multifocal ABC when multiple cystic tumors occur in the same bone and poly-ostotic multifocal ABC when multiple lesions occur in multiple bones [8,15]. This variant seems to be particularly frequent in male patients (5 patients/7 in Angelini A et al's review), and the most reported sites are the femur and the tibia [8]. No case of multifocal ABC of pelvic bones was found.The multifocal forms of ABC are in the majority of cases described metachronously [5,6,8,[13][14][15], the synchronous occurrence in the same patient is exceptional.…”

“…These forms are rare and represent a real diagnostic challenge for clinicians [9][10][11]. Multifocal variant of ABC is particularly exceptional, and since its initial description by Sundaram M et al in 1997 [12], only a few sporadic cases have been reported in the world literature [5,6,8,[13][14][15]. Indeed, the systemic review of English literature made in 2020 by Angelini A et al, found only seven cases of multifocal ABC [8].…”

“…Multifocal variant of ABC is particularly exceptional, and since its initial description by Sundaram M et al in 1997 [12], only a few sporadic cases have been reported in the world literature [5,6,8,[13][14][15]. Indeed, the systemic review of English literature made in 2020 by Angelini A et al, found only seven cases of multifocal ABC [8]. There are two types of multifocal ABC: mono-ostotic multifocal ABC when multiple cystic tumors occur in the same bone and poly-ostotic multifocal ABC when multiple lesions occur in multiple bones [8,15].…”

“…Indeed, the systemic review of English literature made in 2020 by Angelini A et al, found only seven cases of multifocal ABC [8]. There are two types of multifocal ABC: mono-ostotic multifocal ABC when multiple cystic tumors occur in the same bone and poly-ostotic multifocal ABC when multiple lesions occur in multiple bones [8,15]. This variant seems to be particularly frequent in male patients (5 patients/7 in Angelini A et al's review), and the most reported sites are the femur and the tibia [8].…”