JPC SYSTEMIC PATHOLOGY
Musculoskeletal System
April 2019
M-N05

Signalment (JPC #3026261):  11-month-old male Rocky Mountain elk (Cervus elaphus nelsoni)

HISTORY:  This elk presented for anorexia, lameness and thickening of all four distal limbs. Pulmonary nodules were diagnosed radiographically. Tuberculosis was suspected and the animal was euthanized.

HIST0PATHOLOGIC DESCRIPTION:  Bone, metatarsus (per contributor):  Diffusely extending from the cortical surface and markedly elevating the periosteum are numerous perpendicular trabeculae of bone up to 12mm in length, delineated from the peripheral edge of the normal cortex by a basophilic line (resting cement line).  The deep third of new bone extending from the pre-existing cortex is dense and composed of mature lamellar bone, forming well-organized osteons with lower numbers of osteocytes and minimal intertrabecular fibrovascular tissue.  Peripheral trabeculae are composed of irregular woven bone with scalloped margins and numerous haphazardly arranged osteocytes within lacunae.  Between trabeculae of woven bone there is absence of normal marrow elements and trabeculae are separated by a moderate amount of loose intertrabecular fibrovascular tissue.  Woven trabecular bone immediately beneath the periosteum is lined by osteoid seams with 1-2 cells layers of plump reactive osteoblasts.  The periosteum is expanded up to 1.5mm by abundant fibrous connective tissue.

Lung:  Multifocally disrupting and replacing over 70% of the normal lung are multiple coalescing pyogranulomas up to 8 mm in diameter that compress surrounding tissue. Pyogranulomas are characterized by a large central region of abundant eosinophilic cellular and karyorrhectic debris (lytic necrosis) and numerous variably discernible fungal hyphae.  Necrotic centers are surrounded by a basophilic rim of degenerate neutrophils and necrotic debris, and further surrounded by epithelioid macrophages, reactive fibroblasts and mature collagen (fibrosis) and few multinucleated giant cells.  Multifocally surrounding pyogranulomas are few lymphocytes, plasma cells, eosinophils and small caliber blood vessels often regularly spaced and interspersed with active fibroblasts (granulation tissue), and lined by plump endothelium (reactive).  Fungal hyphae are 3-6um wide and regularly septate with dichotomous acute angle branching and parallel walls.  Multifocally, remaining alveoli contain an eosinophilic fibrillar material (fibrin and edema) admixed with occasional neutrophils, macrophages and rare multinucleated giant cells. Focally few bronchioles contain abundant fibrin, neutrophils, macrophages and necrotic debris which replace bronchiolar epithelium. Diffusely, interlobular septa are expanded up to 3mm by fibrous connective tissue.

MORPHOLOGIC DIAGNOSIS: 

  1. Bone, metatarsus:  Periosteal new bone formation (hyperostosis), diffuse, severe, Rocky Mountain elk (Cervus elaphus nelsoni), cervid.
  2. Lung: Pyogranulomas, multiple, marked, with numerous fungal hyphae.

CONDITION:  Hypertrophic osteopathy

SYNONYMS:  Hypertrophic pulmonary osteoarthropathy; “Marie’s disease” or Marie-Bamberger’s disease

GENERAL DISCUSSION: 

Can occur with:

PATHOGENESIS: 

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS: 

TYPICAL LIGHT MICROSCOPIC FINDINGS: 

ADDITIONAL DIAGNOSTIC TESTS: 

DIFFERENTIAL DIAGNOSIS:

Gross (periosteal proliferative lesion)

COMPARATIVE PATHOLOGY:

REFERENCES: 

  1. Ferguson NM, Levy M, Ramos-Vara JA, Baird DK, Wu, CC. Hypertrophic osteopathy associated with mycotic pneumonia in two juvenile elk (Cervus elaphus). J Vet Diagn Invest. 2008; 20: 849-853.
  2. Foster WK, Armstrong JA. Hypertrophic osteopathy associated with pulmonary Eikenella corrodens infection in a dog. J Am Vet Med Assoc. 2006; 228(9):1366-1369.
  3. Johnson R, Lenz S. Hypertrophic osteopathy associated with a renal adenoma in a cat. J Vet Diagn Invest. 2011; 23:171-175.
  4. Madson DM, Loynachan AT, Kariyawasam S, Opriessnig T. Systemic Conidiobolus incongruous infection and hypertrophic osteopathy in a white-tailed deer (Odocoileus virginianus). J Vet Diagn Invest. 2009: 21: 167-170.
  5. Panciera RJ, Mathew JS, Ewing SA, Cummings CA, Drost WT and Kocan AA. Skeletal lesion of canine hepatozoonosis caused by Hepatozoon americanum. Vet Pathol. 2000; 37:225-230.
  6. Craig LE, Dittmer KE, Thompson KG. Bones and joints. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 1. 6th ed. St. Louis, MO: Elsevier; 2016:92-94.
  7. Olson EJ, Carlson CS. Bones, joints, tendons, and ligaments. In: McGavin MD, Zachary JF, eds. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017: 967, 989-990.
  8. Vengust G, Zele D, Svara T, Dolensek T. Hypertrophic osteopathy associated with mycotic pneumonia in a roe deer (Capreolus capreolus). J Wildl Dis. 2018: 54(3): 631-634.


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