Clinical Research

Clinical Orthopaedics and Related Research®

, Volume 469, Issue 7, pp 2019-2027

First online:

Bizarre Parosteal Osteochondromatous Proliferation: A Locally Aggressive Benign Tumor

  • Jibu JosephAffiliated withDepartment of Trauma and Orthopaedics, Glasgow Western Infirmary Email author 
  • , David RitchieAffiliated withDepartment of Radiology, Glasgow Western Infirmary
  • , Elaine MacDuffAffiliated withDepartment of Pathology, Glasgow Western Infirmary
  • , Ashish MahendraAffiliated withDepartment of Trauma and Orthopaedic Surgery, Glasgow Royal Infirmary

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Abstract

Background

Bizarre parosteal osteochondromatous proliferation (BPOP) is a benign lesion of bone, and numerous questions remain unresolved regarding its etiology, diagnosis, and treatment.

Questions/purposes

We present the Scottish Bone Tumour Registry experience of this rare lesion.

Patients and Methods

We performed a retrospective analysis of the Scottish Bone Tumour Registry records. Histologic specimens were reexamined by a musculoskeletal pathologist. Radiographs were reevaluated by a musculoskeletal radiologist.

Results

From 1983 to 2009, 13 cases (13 patients; six male, seven female) were identified. Their ages ranged from 13 to 65 years. All patients presented with localized swelling. Pain was present in five. Antecedent trauma was present in two. Nine lesions affected the hand, three the foot, and one the tibial tuberosity. Twelve lesions were excised and one was curetted. There were seven recurrences of which six were excised. One lesion recurred a second time and was excised. There were no metastases. Radiographs showed densely mineralized lesions contiguous with an uninvolved cortex. Cortical breakthrough was present in one case and scalloping in another. Histologic analysis characteristically showed hypercellular cartilage with pleomorphism and calcification/ossification without atypia, bone undergoing maturation, and a spindle cell stroma.

Conclusions

BPOP is a rare benign lesion that probably is neoplastic, with no gender predilection, and affecting patients over a wide age range. Previously trauma was considered an etiologic factor, but this no longer seems to be the case. The rate of recurrence was 50%, which may indicate a more extensive resection is required for this locally aggressive lesion. No metastases were reported. BPOP should not be mistaken for, or treated as, a malignant tumor.

Level of Evidence

Level IV, retrospective case series. See Guidelines for Authors for a complete description of levels of evidence.