Distal phalanx intraosseous epidermoid inclusioncyst: A rare thing!

Pathological structures called epidermoid bone inclusion cysts are surrounded by a layer of stratified squamous epithelium that contains keratin debris. They go by the name epidermal bone cysts as well. Intraosseous epidermoid cysts are uncommon lesions that can develop as a result of trauma (puncture wound or pressure erosion). They typically affect the toes, phalanges, and head. The distal phalanx of the fingers is where phalangeal involvement most frequently occurs. Despite the fact that the cause of intraosseous epidermal inclusion cysts is still unknown, the majority of patients do recall a prior traumatic event, supporting the post-traumatic origin theory. Following digital trauma or surgery, it is hypothesised that surface epithelial cells are pushed into the underlying osseous compartment.Following the initiating event, symptoms may start to appear months to years later. It is challenging to distinguish intraosseous epidermoid inclusion cysts on radiographs from other radiolucent lesions, necessitating tissue diagnosis.We present a case of a 45-year-old man with right middle finger distal phalanx edoema for five months and a known history of minor blunt trauma. A well-defined expansile hypodense lytic lesion with eccentric phalanx erosion was discovered during radiological analysis. A creamy substance was found inside the lesion after surgery, and it was later determined by histology to be an epidermoid inclusion cyst.Gross examination of the surgical specimen indicated a cystic lesion with significant necrotic regions and pale, creamy material. A burst intraosseous epidermoid inclusion cyst was discovered upon microscopic inspection and was effectively removed.