Bizarre Parosteal Osteochondromatous Proliferation of Bone (Noraʼs Lesion)

Bizarre Parosteal Osteochondromatous Proliferation (Nora Lesion)

“…It can be differentiated from osteochondroma from its lack of communication with the underlying medulla and lack of cortical flaring. 1,4 Microscopically, Nora lesion demonstrates irregular maturation of hypercellular cartilage into bone, producing bone with the characteristic blue quality ("blue bone"). 4 The lobules of cartilage contain atypical binucleate chondrocytes, and between the bony trabeculae, there is a benign spindle cell proliferation.…”

“…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

“…BPOP lesions often are excised early and, as a result, their natural history is not entirely clear [6]. The few that have been observed with time exhibit evolution from a less organized periosteal soft tissue swelling with few calcifications toward a more mineralized lesion and eventually to a completely ossified mass [6,14,24]. This maturation process has been hypothesized to represent a reparative etiology in the response to trauma [11,24,27], despite that the majority of patients described in case reports lack a traumatic history.…”

“…The classic radiographic appearance of BPOP is a well-defined, mineralized round or oval mass with a broad base that arises from the cortex without flaring or corticomedullary continuity [14,18]. MRI is useful to further characterize the radiographic features and display pertinent negatives, such as the absence of soft tissue swelling, soft tissue mass, and cortical destruction.…”

“…The bone component of BPOP consists of well-formed trabeculae of woven bone enmeshed in loose connective tissue [1,14,15,23]. Surgery is the standard treatment for BPOP; however, the appropriate margins of resection are debated owing to the high incidence of recurrence [6,12,14,18,23]. Surgical approaches include marginal resection and continued local resection of any recurrent lesions.…”