Simple Bone Cyst of Metacarpal: Rare Lesion with Unique Treatment

Simple bone cyst or unicameral bone cyst (UBC) are benign cystic lesions commonly found in femur and humerus. However hand is a very rare site of occurrence. Treatment described for UBC of hand commonly involves curettage and bone grafting.

A 7 year old right hand dominant girl presented to us with chief complaints of pain and swelling in right 4th metacarpal since 2 month. On imaging, plain radiographs of right hand showed expansile lytic lesion on Metaphyseal-diaphyseal region of 4th metacarpal with pathological fracture. MRI showed cystic lesions with internal loculations and fluid-fluid levels (Fig 2). There was minimal soft tissue extension. We performed aspiration which showed serosanguinous fluid with haemorrhagic tinge. With the diagnosis of unicameral bone cyst in mind we performed and closed intramedullary nail with k wire. The cyst healed up completely within 2 months. There was no recurrence at 18 month follow up.

In conclusion simple bone cyst is very rare in metacarpal bone. However it should be considered as important differential since it warrants simple treatment and extensive procedures should be avoided.