Bizarre parosteal osteochondromatous proliferation (BPOP, also known as Nora's lesion) is a rare, benign, locally aggressive condition defined as osteochondromatous exostosis arising from the bony cortex. BPOP presents predominantly in the 2nd and 3rd decades of life, and commonly arises from the periosteum of metacarpals and metatarses, though rare locations have been reported, including the long bones, the maxillae, the bones of calvaria, and the sesamoids. The case of an osteochondromatous lesion in an infant with an intra-abdominal mass arising from the iliac wing, an atypical location of be- nign solitary lesions, is reported. Benign solitary lesions are exceptional in this age group. The parents of the patient, who was born in term at 3600 grams, discovered a mass in the left groin and observed decreased movement in the lower left extremity. No history of trauma was reported. When the patient was 5 months of age, AP pelvic X-ray, computed tomography, and magnetic resonance imaging revealed a bony mass displacing intra-abdominal organs anteromedially. Biopsy reported an osteocartilaginous lesion with calcified mature cartilaginous fragments surrounded by plasmacytoid, monotone, fibrinoid cells in myxoid background. Differential diagnosis included osteochondroma, osteochondromyxoma, BPOP, fibrocartilaginous mesenchymoma, chondromyxoid fibroma, periosteal chondroma, soft tissue chondroma, myositis ossificans, and juxtacortical chondroma. Biopsy of the resected specimen deter- mined a diagnosis of BPOP. At 6-month postoperative follow-up, neither symptoms nor complaints related to the mass were present.
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Nied?wiecka M, Kaczmarek P, Krawczyk T, Oszukowski P, Maroszy?ska I. Benign but fatal. A case of a newborn with congenital osteochondroma. Bone 2013;54:169-71.
Stizman-Wengrowicz ML, Pretell-Mazzini J, Dormans JP, Davidson RS. Regression of sessile osteochondroma: a case study and review of the literature. UPOJ 2011;21:73-6.
Herring JA. Tachdjian's pediatric orthopaedics. 3rd ed. W. B. Saunders 2002. p. 1917-24.
Flint JH, McKay PL. Bizarre parosteal osteochondroma- tous proliferation and periosteal chondroma: a compara- tive report and review of the literature. J Hand Surg Am 2007;32:893-8.
Abramovici L, Steiner GC. Bizarre parosteal osteochon- dromatous proliferation (Nora's lesion): a retrospective study of 12 cases, 2 arising in long bones. Hum Pathol 2002;33:1205-10.
Harty JA, Kelly P, Niall D, O'Keane JC, Stephens MM. Bizarre parosteal osteochondromatous proliferation (No- ra's lesion) of the sesamoid: a case report. Foot Ankle Int 2000;21:408-12.
Shankly PE, Hill FJ, Sloan P, Thakker NS. Bizarre par- osteal osteochondromatous proliferation in the anterior maxilla: report of a case. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999;87:351-6.
Joseph J, Ritchie D, MacDuff E, Mahendra A. Bizarre parosteal osteochondromatous proliferation: a lo- cally aggressive benign tumor. Clin Orthop Relat Res 2011;469:2019-27.
Kershen LM, Schucany WG, Gilbert NF. Nora's lesion: bizarre parosteal osteochondromatous proliferation of the tibia. Proc (Bayl Univ Med Cent) 2012;25:369-71.
Torreggiani WC, Munk PL, Al-Ismail K, O'Connell JX, Nicolaou S, Lee MJ, et al. MR imaging features of bizarre parosteal osteochondromatous proliferation of bone (No- ra's lesion). Eur J Radiol 2001;40:224-31.
Lindeque BG, Simson IW, Fourie PA. Bizarre parosteal osteochondromatous proliferation of a phalanx. Arch Or- thop Trauma Surg 1990;110:58-60.
Gruber G, Giessauf C, Leithner A, Zacherl M, Clar H, Bodo K, et al. Bizarre parosteal osteochondromatous pro- liferation (Nora lesion): a report of 3 cases and a review of the literature. Can J Surg 2008;51:486-9.
Carney JA, Boccon-Gibod L, Jarka DE, Tanaka Y, Swee RG, Unni KK, et al. Osteochondromyxoma of bone: a congenital tumor associated with lentigines and other un- usual disorders. Am J Surg Pathol 2001;25:164-76.
Campanacci M, Picci P, Gherlinzoni F, Guerra A, Bertoni F, Neff JR. Parosteal osteosarcoma. J Bone Joint Surg Br 1984;66:313-21.
Rubin JA, Steinberg DR. Turret exostosis of the metacar- pal: a case report. J Hand Surg Am 1996;21:296-8.
Shakib K, Kalsi H, Tsiridis E, Kumar M. Rare case of bizarre parosteal osteochondromatous proliferation presenting in the zygoma. Br J Oral Maxillofac Surg 2011;49:e27-9.
Murphey MD, Choi JJ, Kransdorf MJ, Flemming DJ, Gannon FH. Imaging of osteochondroma: variants and complications with radiologic-pathologic correlation. Ra- diographics 2000;20:1407-34.
Bandiera S, Bacchini P, Bertoni F. Bizarre parosteal os- teochondromatous proliferation of bone. Skeletal Radiol 1998;27:154-6.