Huge chronic expanding hematoma of the iliac bone following multiple hip surgeries: a case report

BACKGROUND: Chronic expanding hematoma is a rare entity resulting from trauma or surgery. This condition usually occurs in soft tissue, such as the trunk or extremities, while chronic expanding hematoma arising from bone has not been reported previously. We describe an unusual case of a huge intraosseous chronic expanding hematoma arising from the ilium, which had grown over a 40-year period following hip surgeries. CASE PRESENTATION: A 57-year-old Japanese woman presented with a 1.5-year history of right hip pain. She had a history of bilateral developmental dysplasia of the hip and had undergone bilateral arthroplasties in childhood. A physical examination revealed a large, firm, immobile mass at her right ilium. Based on radiographic findings, a type of slow-growing bone tumor was suspected, and an incisional biopsy was performed. A histopathologic examination revealed large amounts of old clotted blood within the lesion, and the capsule of the lesion was composed of dense, fibrous, connective tissue. There was no evidence of neoplasia, and chronic expanding hematoma was suspected. The lesion was resistant to conservative treatment, and so we performed an internal hemipelvectomy (including the capsule of the mass) and a reconstruction by hip transposition 2.5 years after the incisional biopsy. There was no recurrence of chronic expanding hematoma at the most recent follow-up of 1 year and 8 months postoperatively. CONCLUSIONS: A chronic expanding hematoma is characterized by its persistence and increasing size more than 1 month after the trauma or surgical event suspected of causing hemorrhage. To the best of our knowledge, this is the first report of chronic expanding hematoma arising from bone. We performed internal hemipelvectomy and hip transposition, and there has so far been no recurrence. This disease may be considered a differential diagnosis for bone tumor when the patient has a history of surgery or trauma, regardless of how many years have passed since the index event.