# Gene-Confirmed Primary Aneurysmal Bone Cysts of the Jaws: A Qualitative Systematic Review of Clinical, Radiologic, and Histopathological Features

## TL;DR

This paper reviews primary aneurysmal bone cysts in jaws, focusing on clinical, radiologic, and histopathological features to aid diagnosis when genetic testing is unavailable.

## Contribution

The study systematically analyzes confirmed primary ABC cases in jaws with a focus on diagnostic features and highlights the need for histopathological markers when genetic analysis is not feasible.

## Key findings

- Primary ABCs showed male predominance and occurred mainly in the mandibular posterior region and TMJ.
- Diagnostic clues included fluid levels on MRI/CT and blood-filled spaces surrounded by fibrovascular septa.
- Recurrence was observed in 6 of 13 cases treated by curettage.

## Abstract

Aneurysmal bone cyst (ABC) is rarely a clinical diagnosis on first take; hence, data pertaining to primary ABC assists in differentiating lesions from related pathologies. The cases of primary ABCs were managed by curettage even with extensive cortical plate expansion, whereas secondary ABCs were managed according to primary pathology. The present review retrospectively studies the case reports of primary ABCs affecting the jaws, reported from the year 2000 (the time when USP6 to CDH 11 gene translocation was detected) to date, to identify cases that were diagnostically confirmed with gene analysis. Confirmed primary ABCs of jaws as defined by the World Health Organization (WHO) 2020 classification were included after a thorough literature search. In cases where gene analysis was not done, criteria considered to diagnose as primary ABC (clinical-radiological characteristics and histopathological features) were studied. Recurrence rate and prognosis were analyzed. A male predominance was noted with a ratio of 2:1. The age group between 10 and 20 years and the mandibular posterior region, followed by the temporomandibular joint (TMJ), were mainly affected. Around 22 of 33 cases showed both buccal and lingual cortical plate expansion. Blown-out cortices, fluid levels on magnetic resonance imaging (MRI) or contrast computed tomography (CT), altered blood, and the key histopathological feature of large blood-filled spaces surrounded by fibrovascular septa were the main clues for diagnosis. Around 28 of 33 cases showed giant cells, and 14 of 33 cases showed calcifications/ossifications. Recurrence was noted in 6 of 13 cases treated by curettage. A majority of primary ABCs are believed to exhibit gene mutations; however, genetic analysis was infrequently performed in the reviewed cases. Since the gene analysis may not be feasible in all cases, studies on histopathological analysis and immunohistochemical (IHC) markers to find clues for confirmatory diagnosis are in need.