INTRAMEDULLARY FIBROUS SCAR 321 EXAMPLES OF A PREVIOUSLY UNREPORTED AVASCULAR FIBROSIS OF JAWBONES

1. INTRAMEDULLARY FIBROUS SCAR 321 EXAMPLES OF A PREVIOUSLY UNREPORTED AVASCULAR FIBROSIS OF JAWBONES Jerry Bouquot,Professor & Chair, Department of Diagnostic Sciences, University of Texas Dental Branch at Houston Robert McMahon, The Oral Surgery Group, Valparaiso, Indiana

2. Next: submucosal fat Normal fatty marrow of the jawsrules of the game • Almost ALL adult marrow is fatty marrow • Fibrous tissue in marrow: • ALWAYSABNORMAL • No fibers around vessels, except arteries • -- Almost invisible reticulum fibers can act • as “communication wires” • Adipocytes are somewhat irregular in size • Capillaries are collapsed, almost invisible • -- Largest normal = 4-5 RBC diameters • No visible sinusoids in adults -- Remaining ones along bone are collapsed • No visible fluid between adipocytes • No marrow hemorrhage with hand curettage • No inflammatory cells between fat cells • No oil cysts (bubbles of liquid fat released • by adjacent dead fat cells) • Bony trabecula are inactive Normal capillary, slightly dilated Inactive, thin trabeculum Normal capillary, slightly dilated Normal capillary, inactive (collapsed) Bouquot, McMahon, Annual meeting, American Academy of Oral & Maxillofacial Pathology, 2010

3. the classic bone scar: bone scar (from infarction) • Exuberant “healing” around old • marrow infarction • Remain indefinitely • Usually no long-term pain Bone scar Bouquot, McMahon, Annual meeting, American Academy of Oral & Maxillofacial Pathology, 2010

4. Next: micro, gross, micro the unclassic bone scars:idiopathic osteosclerosis and condensing osteitis • Fibroblastic proliferation is seen in osteonecrosis, as are lipid-bearing histiocytes. Aegerter, Kirkpatrick, 1975. • Gall & Bennett examined a case of ON of the femur from autopsy in 1942. This may have been the first autopsy report of ON. They found cystic degeneration, replacement fibrosis, old hemorrhage, and fibrous granulation tissue. Aegerter, Kirkpatrick, 1975. Condensing osteitis Idiopathic (ischemic?) osteosclerosis Ischemic osteosclerosis and ischemic cavitation Ischemic osteosclerosis Ischemic cavitation Bouquot, McMahon, Annual meeting, American Academy of Oral & Maxillofacial Pathology, 2010

5. fibrous stroma of cysts/tumors/infectionwe are familiar with some forms of intraosseous fibrosis • We are used to seeing fibrosis within jaws • E.g.: tumors, cysts, periapical infections, • poor healing from fractured jaw • At periphery: reactive bony “wall” • Tumors may infiltrate surrounding marrow • Otherwise: beyond the “wall” = normal Nasopalatine duct cyst Collagen filling marrow space Periapical granuloma Bouquot, McMahon, Annual meeting, American Academy of Oral & Maxillofacial Pathology, 2010

6. the classic fibrous jawbone scar: periapical scar (fibrotic periapical granuloma) Periapical scar Bouquot, McMahon, Annual meeting, American Academy of Oral & Maxillofacial Pathology, 2010

7. Next: text the classic fibrous jawbone scar: INTRAMEDULLARY FIBROUS SCAR? Infarct in bone: “Repair may be slight or complete, with partial fatty or fibrous tissue replacement of the hemato-poietictissue (up to five months after the precipitating episode). Complete regeneration is possible in animals but has never been documented in man. Ficat, Arlet, 980. • Occasional cancellous jawbone • curettings show only viable bone • and dense collagen • Similar to periapical scar • Similar to fibrous mucosal scar Bouquot, McMahon, Annual meeting, American Academy of Oral & Maxillofacial Pathology, 2010

8. Intramedullary fibrous scarMy first case: 1978 – “what the #@^!*% is this?!” • Cortices were completely intact • -- Not fibrous healing defect • Tooth extracted >10 years ago • Endodontic Rx >25 years ago • My diagnosis: Residual periapical scar • David Dahlin’s diagnosis (Mayo Clinic): • Chronic fibrosing osteomyelitis Bouquot, McMahon, Annual meeting, American Academy of Oral & Maxillofacial Pathology, 2010

9. Marrow fibrosis/myelofibrosisrules of the game: fibrosis in ischemic bone damage • Myelofibrosis is an example of ischemic damage in leukemia, as is progressive • fibrous marrow and osteosclerotic changes or osteosclerotic patches. • Greenfield, 1975. • Collagen type III is the usual type; stains with silver salts. Normally there is very • little reticulin, and what there is can be found only around blood vessels and • adjacent to bone. It is increased in a variety of pathologic states associated with • fibrosis. Fatty marrow usually contains 0 to trace reticulin. Strauchen, 1996. • Replacement fibrosis after destruction of the marrow is often quite dense and • acellular, producing a definitive scar. Sherman called it inactive dense fibrosis. • Ficat, Arlet, 1980. • Generalized marrow fibrosis is very suggestive of osteonecrosis but does not • prove a diagnosis of ischemic osteonecrosis. Localized fibrosis can occur as a • result of a healing or poorly healed bone infarct. Wittels, 1985. • Osteonecrosis is associated with poorly vascular fibrous tissue in the marrow • spaces. Catto in Davidson, 1976. Bouquot, McMahon, Annual meeting, American Academy of Oral & Maxillofacial Pathology, 2010

10. Objectives/hypothesis/methods • Objectives: • To characterize a previously unreported • intramedullary lesion of the jaws • To compare IFS with normal • Hypothesis: • Dense fibrous scars occur within marrow spaces, just as they do in extraosseous tissues • Methods: • Drawn from database of 101,433 oral • surgical pathology samples • >11,000 bone/marrow samples • Excludes apical lesions • All samples re-evaluated blindly • Cases: n = 321 (Intramed. fibrous scar) • Controls: n = 100 (Normal bone/ marrow) Dense collagen fibers (and hemosiderin deposits) Bouquot, McMahon, Annual meeting, American Academy of Oral & Maxillofacial Pathology, 2010

11. Demographics, lesion characteristics • Cases (n = 321): • Average age = 48 years (21 – 90 years) • 76% females • 98% molar/premolar regions • 70% in mandible • 51% in old surgical site • 38% with pain • Controls (n = 100): • Average age = 43 years (16 – 84 years) • 69% females • 100% molar/premolar regions • 42% = mandible • ?? In old surgical site • 12% with pain Bouquot, McMahon, Annual meeting, American Academy of Oral & Maxillofacial Pathology, 2010

12. results (321 cases) • Well demarcated margins • -- Rare: sclerotic ring around lesion • Fibrosis: • -- 84% = dense, “avascular” • -- 14% = moderately dense (focal) • -- 2% = myxoid change (focal) • 43% = lymphocytic infiltration • -- Usually small, focal area • -- Occasional histiocytes, plasma cells • Occasional hemosiderin deposits Dense collagen fibers (and hemosiderin deposits) Bony ring around scar Sharp margins Moderately dense collagen fibers Bouquot, McMahon, Annual meeting, American Academy of Oral & Maxillofacial Pathology, 2010

13. Intramedullary fibrous scarradiographic appearances Well demarcated radiolucency Moderately well demarcated Poorly demarcated radiolucency Eagle’s nest radiolucency Bouquot, McMahon, Annual meeting, American Academy of Oral & Maxillofacial Pathology, 2010

14. Intramedullary fibrous scarwith small islands/trabecula of inactive bone Bouquot, McMahon, Annual meeting, American Academy of Oral & Maxillofacial Pathology, 2010

15. Intramedullary fibrous scaroccasional: myxoid change, bone islands Dense collagen fibers Bouquot, McMahon, Annual meeting, American Academy of Oral & Maxillofacial Pathology, 2010

16. Intramedullary fibrous scardifferent from other marrow fibroses? Reactive fibrosis (poorly demarcated margins) Marrow fibrosis Ischemic myelofibrosis (wispy, streaming between fat cells) Chronic fibrosing osteomyelitis Bouquot, McMahon, Annual meeting, American Academy of Oral & Maxillofacial Pathology, 2010

17. chronic fibrosing osteomyelitisvs. Intramedullary fibrous scar Chronic fibrosing osteomyelitis Bouquot, McMahon, Annual meeting, American Academy of Oral & Maxillofacial Pathology, 2010

18. Intramedullary fibrous scardifferent from reactive new bone or osseous dysplasia Reactive new bone Cemento-osseous dysplasia Fibrous scar Bouquot, McMahon, Annual meeting, American Academy of Oral & Maxillofacial Pathology, 2010

19. Marrow fibrosisclassification • With mature, inactive bone: • Ischemic myelofibrosis • -- Reticular degeneration • Reactive marrow fibrosis • Chronic fibrosing osteomyelitis • Intramedullary fibrous scar • -- With foreign material • -- Periapical scar • Chronic granulomatous osteomyelitis • With immature, active bone: • Reactive new bone • Benign fibro-osseous lesions • Cemento-osseous dysplasias Bone marrow edema Bone marrow edema Intramedullary fibrous scar Bouquot, McMahon, Annual meeting, American Academy of Oral & Maxillofacial Pathology, 2010

20. Next: socket cross section Intramedullary fibrous scaretiology? • Poor healing from surgery? • Poor healing from infarction? • Poor healing from focal infection? • Response to foreign material? • -- 14% = foreign material • (e.g. amalgam, endo Rx. paste, • augmentation material) • Ischemia vs. inflammation • 86% = idiopathic via histology Maxillary socket filled with collagen (7 years after extraction) Residual socket in cross section Residual socket with fiber fill Residual socket beneath pontic Bouquot, McMahon, Annual meeting, American Academy of Oral & Maxillofacial Pathology, 2010

21. chronic fibrosing pulpitisin patients with intramedullary fibrous scar With dystrophic calcification Globular hyalinization (32 year old female) Bouquot, McMahon, Annual meeting, American Academy of Oral & Maxillofacial Pathology, 2010

22. Intramedullary fibrous scar14% with foreign material Petrolatum based dry socket medication (myospherulosis?) Amalgam Endodontic paste Dry socket medication Bouquot, McMahon, Annual meeting, American Academy of Oral & Maxillofacial Pathology, 2010

23. Intramedullary fibrous scarwith bone augmentation material Cadaver bone chips Bovine bone chips Hydroxyapatite and ?? Cadaver bone chips Bouquot, McMahon, Annual meeting, American Academy of Oral & Maxillofacial Pathology, 2010

24. Intramedullary fibrous scarwith hyaline angiopathy Hyaline angiopathy Hyaline angiopathy Bouquot, McMahon, Annual meeting, American Academy of Oral & Maxillofacial Pathology, 2010

25. Intramedullary fibrous scarconclusions • Focal regions of dense, avascular fibrosis • do occur within medullary spaces • Possibly secondary to improper healing • after surgery, but the etiology is unclear • We propose “intramedullary fibrous scar” • as the appropriate diagnostic term • Clinical significance is unclear but a • sizeable proportion of cases are • associated with pain Intramedullary fibrous scar Intramedullary fibrous scar (adjacent teeth are viable) Normal marrow Bouquot, McMahon, Annual meeting, American Academy of Oral & Maxillofacial Pathology, 2010

26. INTRAMEDULLARY FIBROUS SCAR 321 EXAMPLES OF A PREVIOUSLY UNREPORTED AVASCULAR FIBROSIS OF JAWBONES Jerry Bouquot,Professor & Chair, Department of Diagnostic Sciences, University of Texas Dental Branch at Houston Robert McMahon, The Oral Surgery Group, Valparaiso, Indiana