Bone & joints
Other chondrogenic tumors
Bizarre parosteal osteochondromatous proliferation
Author: Nat Pernick, M.D.
Last author update: 1 August 2013
Last staff update: 12 May 2023 (update in progress)
Copyright: 2003-2023, PathologyOutlines.com, Inc.
PubMed Search: Bizarre parosteal osteochondromatous proliferation
Table of Contents
Definition / general | Radiology description | Radiology images | Treatment | Case reports | Gross description | Microscopic (histologic) description | Microscopic (histologic) images | Molecular / cytogenetics description | Differential diagnosis | Additional referencesCite this page: Pernick N. Bizarre parosteal osteochondromatous proliferation. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/bonebizarreparosteal.html. Accessed September 21st, 2023.
Definition / general
- Also called Nora lesion
- Rare form of myositis ossificans, resembles subungual (Dupuytren’s) exostosis, except for t(X;6) in the latter (Am J Surg Pathol 2004;28:1033)
- 75% affect small tubular bones of hands and less commonly the feet; do not involve the nailbeds
- 25% affect large bones
- Usually ages 20 - 39 years
Radiology description
- Hands: heavily calcified mass attached to underlying cortex / periosteum but not continuous with it (so not an osteochondroma)
- Long bones: lesions may be destructive or in soft tissue
- Benign but may recur locally (35 - 54%)
Radiology images
Contributed by Mark R. Wick, M.D.
Various images
Treatment
- Surgical excision with wide margins
Case reports
- 18 year old woman with associated fibrosarcoma (Skeletal Radiol 2001;30:44)
Gross description
- Resembles small osteochondroma
Microscopic (histologic) description
- Irregular maturation of cartilage in bone produces chondro-osteoid with characteristic blue quality (“blue bone”)
- Contains enlarged, bizarre, binucleated chondrocytes with maturation into bone
- Spindle cell proliferation between bony trabeculae without atypia
Microscopic (histologic) images
Contributed by Mark R. Wick, M.D.
Various images
Nora lesion foot
Molecular / cytogenetics description
- t(1;17)(q32;q21) or variant translocations involving 1q32 in one study (Hum Pathol 2004;35:1063)
Differential diagnosis
- Florid reactive periostitis
- Juxtacortical chondrosarcoma
- Parosteal osteosarcoma
- Periosteal chondroma
- Periosteal osteosarcoma
- Osteochondroma
Additional references
