Bizarre parosteal osteochondromatous proliferation of bone

Abstract

We describe 22 cases of bizarre parosteal osteochondromatous proliferation, or Nora's lesion. These are surface-based osteocartilaginous lesions typically affecting the hands and feet. All patients were identified from the records of a regional bone tumour unit and were treated between 1985 and 2009. Nine lesions involved the metacarpals, seven the metatarsals, one originated from a sesamoid bone of the foot and five from long bones (radius, ulna, tibia, and femur in two). The mean age of the patients was 31.8 years (6 to 66), with 14 men and eight women. Diagnosis was based on the radiological and histological features. The initial surgical treatment was excision in 21 cases and amputation of a toe in one. The mean follow-up was for 32 months (12 to 162). Recurrence occurred in six patients (27.3%), with a mean time to recurrence of 49 months (10 to 120). Two of the eight patients with complete resection margins developed a recurrence (25.0%), compared with four of 14 with a marginal or incomplete resection (28.6%). Given the potential surgical morbidity inherent in resection, our data suggest that there may be a role for a relatively tissue-conserving approach to the excision of these lesions.

Bizarre Parosteal Osteochondromatous Proliferation (Nora Lesion)

“…Recurrence rate after local excision is high, ranging between 20% and 55%. 3,4,6,16 The degree of resection required to prevent recurrence remains controversial. 3 Intra-lesional excision using curettage is generally not recommended due to association with higher recurrence rate.…”

“…3,4,6,16 The degree of resection required to prevent recurrence remains controversial. 3 Intra-lesional excision using curettage is generally not recommended due to association with higher recurrence rate. 17 Some surgeons recommend formal excision of the pseudocapsule, underlying periosteum, and any suspicious-looking cortex to ensure a clear margin.…”

“…Most reports on Nora lesion did not discuss the reconstructive method used-that is, autograft, allograft, or no graft. 1,2,3,7,8,9,14,17,18 Given the rare nature, high local recurrence rate, and lack of adjuvant therapy, Nora lesion should have long-term follow-up. Timeline between excision and recurrence has been reported to be between 2 months and 2 years.…”

“…There is no official treatment guideline and it has a high recurrence rate post-excision. 3,4 Due to its rare presentation, Nora lesion can easily go unrecognized and therefore inappropriately managed. A delayed presentation can result in aggressive surgical management such as a ray amputation that significantly affect hand function.…”

Asymptomatic Upper Arm Mass in a 37-year-old Woman

“…Some advocate for wide surgical margins, including the pseudocapsule and any periosteal tissue, in an effort to reduce recurrence [2,3,9,10,15,16]. Berber et al [3] reviewed 22 cases of BPOP treated with either marginal or wide resection and found similar recurrence rates of 28.6% and 25% respectively, with a mean followup of 32 months. The recurrence times reported in the literature range from 2 to 84 months [12,18].…”