# Case Report: Adult proximal humeral aneurysmal bone cyst: radical resection and reconstruction with osteoconductive allograft & reverse arthroplasty—Ecuador's first reported case and functional outcomes

## TL;DR

This case report describes the successful treatment of a rare adult bone cyst in Ecuador using advanced surgical techniques and highlights the importance of tailored approaches in orthopedic oncology.

## Contribution

The paper presents Ecuador's first reported case of adult proximal humeral aneurysmal bone cyst and its innovative surgical management.

## Key findings

- Radical en bloc resection combined with single-stage reconstruction achieved functional restoration in an adult ABC case.
- Hybrid graft-prosthesis strategies using osteoconductive allograft and reverse arthroplasty showed promising outcomes.
- Molecular diagnostics are recommended to confirm primary lesions and guide treatment decisions.

## Abstract

Aneurysmal bone cysts (ABCs) are rare benign lesions, with adult cases being exceptionally uncommon. This report details a multidisciplinary approach for managing a proximal humeral ABC in an adult, emphasizing functional restoration.

A 36-year-old male presented with progressive pain, swelling, and restricted shoulder mobility. Imaging revealed an expansile lytic lesion with “soap-bubble” morphology. Histopathology confirmed a primary ABC. After failed conservative management, radical en bloc resection was performed, followed by single-stage reconstruction using osteoconductive allograft, reverse shoulder arthroplasty, and rotator cuff repair.

This case demonstrates the efficacy of aggressive, single-stage reconstruction in adult ABCs, combining advanced orthopedic and oncologic principles. It advocates for molecular diagnostics to confirm primary lesions and supports hybrid graft-prosthesis strategies to optimize outcomes. The success of this approach provides a framework for managing rare, large ABCs in adults, encouraging further exploration of tailored surgical innovations in orthopedic oncology.