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  • Writer's pictureRobin R Varghese, PT.

A quick look at Nora's Lesion or Benign Parosteal Osteochondromatous Proliferation(BPOP)

Nora’s Lesion


  • Nora lesion is a rare Benign Parosteal Osteochondromatous Proliferation or BPOP involving feet and hand.

  • It is characterized by a parosteal mass containing cartilage, fibrous, and bone tissues.

  • Since the time of its discovery, only few cases have been reported in the literature.

  • It was first described by Nora et al in 1983 who reported 35 cases affecting mainly the hands and feet.

  • It grows rapidly and is reported to recur in 50% of the cases following resection.

  • Aggressive features on imaging and confusing results on histopathological studies make its diagnosis difficult.

  • Although it can occur at any age, BPOP most commonly presents in the third and fourth decades, with no gender predilection. It occurs mainly in adults and its occurrence in children and adolescents was only rarely described in the literature. However, when occurring in younger ages, some of the lesions can grow in their size, causing angular deformities.

  • The etiology or cause of BPOP is still unknown. It remains controversial whether BPOP is a reactive proliferative process or a neoplastic lesion

  • BPOP typically presents with pain and bony swelling that progressively increases in size and typically occurs without a history of trauma, though some authors suggest that it may be due to a repetitive trauma

  • Accurate diagnosis is essential to guide treatment strategy, as BPOP can resemble other benign and malignant lesions such as osteochondroma, myositis ossificans, periosteal chondrosarcoma, and parosteal osteosarcoma.

  • Hands and feet being the most common sites, followed by the long bones. Other rare sites have also been reported, such as the skull, maxilla, mandible, sesamoid bone, and vertebrae.

  • There is also a report of BPOP involving the scapula, specifically the scapular spine. Therefore, BPOP should be included in the list of differential diagnoses for surface bone lesions of the scapula.

  • Radiologically, it appears as a calcified mass attached to the bone cortex1 and can mimic an exostosis, an osteochondroma or a malignant condition.

  • The mainstay of treatment for BPOP is surgical resection. Although there are no reported cases of malignant transformation or metastasis, follow-up is necessary due to the high risk of recurrence, which has been reported as 29% to 55% within the first two years following the initial treatment.

  • We at Valley Healing Hands, Brownsville, Texas provide the best physical therapy care for BPOP or Nora’s lesion. Our Physical therapists are highly qualified and will guide you through pre and post surgical care, provide you a customized regime and will walk you through the entire session. Our patients are completely satisfied with our services and you may check what they have to say about us here and get connected to us here.



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