Pathology Associates Of Lexington, P.A.
Pathology Associates Of Lexington, P.A.
Pathology Associates Of Lexington, P.A.
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        Bone & Joint Pathology
  • Arthroscopic issues:
    1. chronic pain lesions: inflammation vs. traumatic vs. degeneration vs. crystallosis. Inflammation can be low-grade septic [L09-10380].
    2. effusion situations: infectious vs. inflammatory (don't forget FMF) vs. crystallosis. Acute inflamation can be organism induced or free urate crystal induced fibrinoleukocytic [L13-14888].
    3. synovial biopsies & joint debridement: DDX = infectious vs.[important link!] crystallosis vs. "reactive arthritis" [L11-8899](ReA = autoimmune in response to infections, examples being chlamydia induced "Reiter's syndrome", "Poncet's disease" associated with TB, enteropathic [Yersinia enterocolitis & even Crohn's associated arthritis] cat-scratch disease;...though no organism vs. rheumatoid arthritis (RA) vs. ankylosing spondylitis associated arthritis (SpA) vs. psoriatic arthritis (PsA) 4; vs. "reactive changes" (osteoarthritic & post-operative & other) vs. detritic synovitis or arthropathy (bone, cobalt-chromium, titanium detritus from worn natural or prosthetic joint surfaces, polarized-light refractile polyethylene [L09-3745] or silicone [L09-5227], voids in fibrous tissue due to methylmethachrylate cement dissolved out during tissue processing) vs. as-yet-to-be-determined etiology [L09-8080]. Detritic material may be scant so that one thinks of a low-grade reactive arthritis (ReA) until the scant detritus is detected [13-3413 & L13-3422]. Adipose-like clear round spaces in synovial lamina propria which might be arthroscpic-artifact-induced pneumatosis (L12-15790).
      • non-postprocedural-based arthropathy detected: Is synovitis present or not (see the 3 parameter...surface-cell-layer increase, stromal-cell density increase & inflammatory infiltrate intensity...assessment by Krenn score6)?
        1. rheumatoid arthritis (RA): RA (even from an asymptomatic joint) & ReA can look similar6 with lymphocytes & plasma cells [L09-5537].
        2. reactive arthritis (ReA): ReA (even from an asymptomatic joint) & RA can look similar6 with lymphocytes & plasma cells [L09-5537].
        3. osteoarthritis (OA) or DJD : the synovium reacts in a variety for 4 ways...
          • "inflammatory osteoarthritis" (OA): OA normally has some "reactive changes" but can have synovial reaction with lymphoid follicles. Said to most commonly affect distal finger joints.
          • hyperplastic (OA): from simple surface cell hyperplasia to villiform structures with or without some increased bulk of stroma.
          • fibrotic (OA): there is relatively little surface-cell participation but increased stroma has become fibrotic, suggesting a stable, longstanding situation.
          • detritus-rich synoviopathy (OA): with or without associated surface-cell participation, stroma has incorporated cartilage & bone "wear & tear" microfragments; watch out for ochronosis generated detritus, which may become hypertrophic by this detritic etiology, the enlargement due to such as a granulation-tissue-like reaction with the detritus [L11-1158].
        4. hypertrophic synoviopathy: without real inflammatory reaction of RA & just some micro-bulky stromal increase of fibrous component...maybe a joint response to old injury [L09-8064]. Maybe it is OA & we were not given the information.
        5. infectious: if acute, look hard for evidence of non-infectious fibrinoleukocytic urate induced exudate. If plasma-cell rich, think of luetic or rheumatoid [L14-1132]. And, there can be a nonspecific chronic fibrinous OA with the fibrin containing degenerative cartilageas pseudogout foci in the fibrin [L14-2122].
        6. detritic athropathy: age & life-related osteoarthritic type, see above; neuropathic...Charcot is a variant & diabetic is just one neuropathic etiology. Also in ochronosis. See post-procedural type, below.
        7. siderotic synovitis or synoviopathy: results from chronic hemarthrosis, is a focal to diffuse proliferation of siderotic synovium, and can resemble pigmented villonodular synovitis (PVNS). Look for a coagulopathy. Also could present as nodule or ganglion cyst of the synovial sleeve of a tendon [L11-8689]. See post-procedural type, below.
      • postprocedural-related arthropathy detected: Is synovitis present or not (see the 3 parameter...surface-cell-layer increase, stromal-cell density increase & inflammatory infiltrate intensity...assessment by Krenn score6)?
        1. postoperative infectious.
        2. postoperative proliferative synoviopathy.
        3. postoperative detritic athropathy:
          • acute postoperative osteoarthritic-like with incorporation and organization of scattered bits of foreign debris and redisual bone, cartilage, and maybe even soft, fibrin-clot loose bodies [L09-6257].
          • chronic postoperative (especially prosthetic failure): And, when there is a joint surgery failure, then in the manner of an exuberant "proud flesh" granulation tissue reaction in a skin wound, one might see synovialization (a sort of pseudosynovial reaction) of structures with papillary structures and incorporation of detritic bone dust, cement, or metallic [L11-12136] or nonmetallic prosthetic wear debris & polarized-light positive incorporation of suture material debris = "exuberant post-operative-repair arthropathy ", especially if there was some post-operative retearing of joint components [L09-6128].
        4. siderotic (or hemosiderotic) synovitis or synoviopathy: postoperative histiocytic (siderotic macrophages) post-hemorrhagic arthropathy where the synovium may organize a hemorrhagic arthrosis into a "rusty" siderotic synoviopathy; if continues into a chronic hemarthrosis, is a focal to diffuse proliferation of siderotic synovium, and can resemble pigmented villonodular synovitis (PVNS). Look for a coagulopathy [L09-3745]. Worth checking for an occult coagulopathy.
        5. postoperative fibrinous arthropathy or synoviopathy: seen as debridement material from joint surfaces [L09-6806] & sometimes in the form of fibrinous "loose bodies" & sometimes organizing of the surface of bare medullary bone [L09-7701].
        6. tear associated reparative synovitis or arthropathy: in association with a complex meniscal or rotator cuff tear, for example, synovium may be "stirred up" enough to have changes remindful of ReA but with the impression that plasma cells & lymphoid micronodules are much less intense [L09-6322] than expected with a systemic immuno-reaction.
  • Foot & ankle surgery:
    1. bunion: irregular histological change of no specific pattern.
      • hallux (big toe) abducto valgus (common) type (HAV)...hallux valgus: big toe deviates away from the body midline & toward the other toes; when it is so bad that it affects the 2nd toe which then in some way encroaches on & limits the great toe = a variant of "hallux limitus" [L09-6328 ]. When that associated first metatarsal deviates notably (20 degrees or more) toward the patient's body's midline because of an HAV, it becomes HAV with "metatarsus premus varus" [L09-14113]. Hallux interphalangeus10 is thought to be a developmental bend in the phalanx segment that is removed by osteotomy [L12-8377].
      • hallux varus: big toe deviates away from others & toward the body midline.
      • tailor's bunion (TB): This is a prominence or 'bump', which occurs on the outside of the foot at the base of the small toe.
    2. hallux (big toe) rigidus: a DJD condition of the big toe [L09-13987] that can first be a hallux limitus; treated surgically by removing the articular-edge, DJD-type-hypertrophic, restricting "lip" or ridge of osteocartilagenous or osteophytic overgrowth (procedure = cheilectomy [L10-1698]) at the metatarsophalangeal articulation. Synonym = hallux flexus.
    3. hallux dolorosus: painful big toe (for a variety of reasons).
    4. hammer toe, claw toe, mallet toe, curly toe: [L09-6204] good images here; hallux malleus is hammertoe deformity affecting the big toe.
    5. arthrodesis tissue: during surgical fixation of a joint for any number of reasons, we might get tissue (arthrodesis = artificial ankylosis; syndesis)[L11-1486].
    6. disorders of peripheral tendon insertion (enthesopathy): lesions in the achilles area present with heel pain over the area of tendon insertion (achillodynia); surgical specimens range from Haglund's deformity (exostosis) osteotomy or exostectomy removal, with or without bursectomy; gouty tophi to debridement of post-rupture problematic areas; to removal of "insertional tendonosis or tendonopathy" tissue (histology is of nuclear disorganization & fibrocartilagenous metaplasia (polarized light exam finds the H&E-obscured refractile tendon collagen) and insertion of streaks & inclusions of small vessels[L08-10653; L09-9655]).
    7. exostoses (osteophytes): these may be osseous or osteocartilagenous & are benign but capable of causing significant problems (from sinus obstruction to radiculopathy).
    8. Morton's neuroma: usually located in the 3rd interspace of the foot, the histology is sometimes fairly vague as to appreciating the neuromatous basis by H&E [L10-11373].
  • Spinal issues: even with "mini" surgery, soft tissue and bone are removed to provide exposure, and these tissues might contain occult evidence of unsuspected local or systemic disease.
    1. See our neuropathology page.
    2. Back pain...Dr. Shaw's website file. Lumbago is a catch-all name for chronic low back pain. Core biopsy during vertebroplasty is to assure that vertebral body collapse was not due to occult myeloma (or other neoplasia) or other occult disorders than osteporosis.
    3. Vertebral body fracture: these may be treated at our hospital percutaneously by radiologists (low/no pressure cement stabilize damage) or neurosurgeons (higher pressure cement restore collapse height). Since collapse is usually osteoporotic...but may be neoplastic, we often get a documentary core biopsy.
    4. HNP: the disc has a central gel-like myxocartilagenous nucleus3 & an inner fibrocartilagenous annulus (homogeneous chondroid matrix3) and an outer ligamentous-like (ligatoid "fibrous" in that matrix is linear3) annulus; disc removed for scoliosis (essentially normal) vs. degenration vs. prolapsed or herniated; is it simple with mostly disc or complicated by bone & soft tissue reactions or encroachments? The only consistent finding (if a third to 50% of specimen processed) is focal reactive ingrowing neovascularization2. If you get what was not herniated, you may see reactive cartilagenous chondrocyte nuclear clusters (chondron clusters)...also in degenerated3 joints. You may find unsuspected urate deposits [L10-2555].

      You may find unsuspected ochronosis, the melanin-like pigment of which is best seen grossly as brown staining (if suspected, check lab for a urine sample to see if it has oxidized to a dark color; add a little 2% ferric chloride from histology special stain &, if has alkaptonuria & positive for homogentisic acid spilling in urine, the urine will turn black). Be aware that some agent from surgery gets in with specimens (about 2010-2013) which gives some brownish stain visble on the H&E slides but not grossly.

    5. Spinal stenosis: due to osteoarthritic bone hypertrophy, ligament hypertrophy, occult malignancy, occult inflammatory hypertrophic encroachment is best surgically treated with good vieing so that decompression is exactly right. Pain management doctors are beginning to offer a less-exacting procedure called MILD (minimally invasive lumbar decompression).
    6. Radiculopathy: due to or associated with disc portion, boney stenosis, osteophytes, foramenal soft tissue hypertrophy, bursitis of a facet bursa [L13-2843], or what?
  • Knee surgery: one might see degenerative changes (arthroscopic articular smoothness loss and findings of visible defects or fibrillations are known as "chondrosis"), synovitis, synovial hypertrophy, reactive pseudovillous and surface hypercellularity; if many plasma cells, think of RA or chronic infectious or other autoimmune. Intra-joint-space synovial bridges = "plica synovialis" [L08-10657]. Chondrocalcinosis...pseudogout [L08-12251]...(calcium pyrophosphate H&E purplish granular deposits which partly polarize as squares, rectangles or rhomboids): may be debrided from articular, meniscal, or synovial sites. Beware that the H&E purple color may be lacking when (1) decalcification is used or (2) too long acid H&E8 has entirely removed the calcium component [L11-373] so that only rounded to oval colorless intracartilagenous crystal-containing voids are seen. But, there is a significant differential diagnosis (DDX)! Chondromalacia may manifest histologically in H&E preps as similar rounded or hazy pale single or fused areas of granular or slightly fibrillar cartilage degeneration (on high power...even oil immersion exam, there are no crystal shapes [L13-14089]...a sort of pseudocrystallosis). Osteophytes and/or osteoarthritic degenerative change (eosinophilc and condensed [inspissated] articular cartilage change of chondromalacia) may be debrided or shaved from the joint surface. One might also degenerative change and dystrophic calcification [L13-10542] at first remindful of calcium pyrophosphate. We also get frozen sections to r/o initial sepsis (criteria) or residual sepsis following sepsis treatment.
    • arthroplasty: is it total knee or less (probably best to word your report so as to not attempt quantitative interpretation about the extent)?
    • arthroscopic: debridement of meniscal & ACL ligament tears & loose bodies; smoothing of the articular pits or ulcers of osteochondritis dessicans (OCD) [L09-2601]...the debridement tissues are irregular osteophyte-like osteochondral tissues.
  • Bursal surgery:
    • subacromial bursitis: shaver removal of bursa HERE.
  • Hip surgery:
    • arthroplasty, standard HERE: for DJD, aseptic necrosis, fracture. Look for osteoporosis as well as any suggestion of osteomalacia [L09-942].
    • femoral head "resurfacing": the DJD changes are removed & an articular cap implanted as a much lesser surgery than removing the whole head HERE.
  • Shoulder surgery: specimen may show synovitis, synovial hypertrophy, reactive pseudovillous and surface hypercellularity; if many plasma cells, think of RA or chronic infectious or other autoimmune. Intra-joint-space synov ial bridges = "plica synovialis". Calcinosis: may be debrided from articular, meniscal, or synovial sites. Osteophytes and/or osteoarthritic degenerative change (eosinophilc and condensed...inspissated...articular cartilage change of chondromalacia) may be debrided, shaved, from surface.
    • SLAP surgery (superior glenoid labral ligament from anterior to posterior tear or instability) may be debridement (the labrum is fibrocartilaginous), repair, or biceps tenodesis (tendon trimming and relocation) for ligament tear/sprain HERE. [L08-11562; L08-11325]. A Bankart repair consists of re-attaching the glenoid labrum to its original site at the margin of the glenoid for a Bankart’s lesion [L10-12912] where the glenoid labrum is detached from its bony attachment with the glenoid at the front (anterior aspect & due to anterior partial (subluxation) or full dislocation of the joint HERE.
    • rotator cuff surgery: this "cuff" is sort of a joint capsule formed by the insertions of the broad fibrous tendons of 4 shoulder muscles. One might get some debridement tissue if torn & maybe some decompression tissues HERE.
    • acromioplasty, A-C mpingement, or subacromial decompression surgery: removing spurs, peritendonal scar tissue, maybe some or all of bursal tissue, or even some tendonesis tissue HERE.
    • distal acromioplasty: for acromio clavicular arthritis.
    • internal impingement surgery: usually due to repetitive throwing, there is a repetitive contact of the greater tuberosity of the humerus with the back of the glenoid labrum and the undersurface of the rotator cuff.
    • HAGL surgery: traumatic dislocation and tearing of tissues = the ligaments that join the humerus to the glenoid tear away from their base on the humerus, a HAGL lesion (humeral avulsion of the glenohumeral ligaments). It may be accompanied by a SLAP lesion, labral tear, or a tear of the rotator cuff tendons.
  • Elbow surgery:
    • tennis elbow (lateral epicondylitis): where the common extensor muscle tendon inserts, & we could get some "tendon release" tissue.
    • arthroscopic: loose bodies from osteochondritis dissecans in young folks to DJD material in older folks...maybe even crystallosis.
  • Hand & wrist surgery:
    1. carpal tunnel surgery: especially increased likelihood to be etiologically related to amyloidosis when bilateral.
    2. ganglion cysts: these will sometimes go away when needle-aspirated. The dermatological mucinous cyst of a digit is essentially a ganglion cyst.
  • Tumor & tumor-like:
    1. localized giant cell tumor of synovium [L09-2837].


  1. Am. College of Foot & Ankle Surgeons website.
  2. Weidner N & Rice DT, "Intgervertebral Disc Material:...", (100 HNP cases vs. 40 autopsy samples) Human Pathology 19(4):406-410, April 1988.
  3. Ford JL, et. al., "Cellularity of Human Annulus Tissue:...", Histopathology 41:531-537, 2002.
  4. Kruithof E, et. al., "Synovial histopathology of psoriatic arthritis, both oligo- and polyarticular, resembles spondyloarthropathy more than it does rheumatoid arthritis", Arthritis Research & Therapy, 7:R569-R580, 2005.
  5. histopath of early RA & longstanding RA (
  6. Krenn V, et. al., "Synovitis score: discrimination between chronic low-grade and high-grade synovitis", Histopathology 49(4):358 - 364, October 2006.
  7. Wheeless' Textbook of Orthopedics...on line. lots of orthopedic info here.
  8. Ohira T and Ishikawa K, "Concise report. Preservation of calcium pyrophosphate dihydrate crystals: effect of Mayer's haematoxylin staining period", Ann Rheum Dis 60(1):80-82, 2001.
  9. Miettenin, Marku, Modern Soft Tissue Pathology, Tumors and Non-neoplastic Conditions, 1105 pages, 2010.
  10. foot surgery atlas (with definitions) at The Foot and Ankle Clinic.

(posted 17 October 2008; latest addition 6 April 2014)

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