JPC SYSTEMIC PATHOLOGY
Musculoskeletal System
March 2019
M-M05

Signalment:  Stillborn piglet of unknown gender

HISTORY (JPC #1810706):  Tissue from 1 of 3 stillborn piglets, which had thickened forelegs.

HISTOPATHOLOGIC DESCRIPTION:  Radius/ulna with adjacent skeletal muscle and tendons:  Radiating diffusely and circumferentially from the surface of normal cortical bone and markedly elevating the overlying periosteum is a circumferential layer of trabecular bone up to 4 mm thick, and composed of thin, trabeculae of woven bone oriented perpendicular to the surface of the bone, and which lack normal bone marrow elements and are separated by loose fibromyxomatous connective tissue.  Diffusely, the periosteum is markedly thickened up to 250 um by fibrous connective tissue, and the inner periosteal margin is lined by up to 5 layers of osteoblasts separated by variable amounts of osteoid.  The connective tissue surrounding the trabeculae is sparsely vascular  and contains numerous loosely and haphazardly arranged spindle to stellate cells and wispy fibrous connective tissue widely separated by clear space (edema).  Connective tissue from the thickened, reactive periosteum merges and fuses with adjacent tendons and separates and surrounds markedly atrophied skeletal muscle.  The connective tissue elements surrounding the periosteum are thickened and edematous.   Surrounding skeletal muscle contains shrunken and atrophied myofibers and regenerative, multinucleated fibers, which are surrounded by edema.  There is a focal area of periosteal mineralization, and multifocal mild scattered hemorrhage and perivascular edema.

MORPHOLOGIC DIAGNOSIS:  Radius/Ulna:  Periosteal new bone formation (hyperostosis), diffuse, severe, with edema and marked muscle atrophy, breed unspecified, porcine.

CONDITION:  Congenital hyperostosis

SYNONYMS:  Congenital porcine cortical hyperostosis, diaphyseal dysplasia, congenital thick foreleg, “thick legs”

GENERAL DISCUSSION:

PATHOGENESIS:

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS:

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY:

REFERENCES:

  1. 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. Philadelphia, PA: Elsevier; 2016: 53, 91-94.
  2. Decker S, Volk HA. Dorsal vertebral column abnormalities in dogs with disseminated idiopathic skeletal hyperostosis (DISH). Vet Rec. 2014;174(25):632.
  3. Doize B, Martineau G. Congential hyperostosis in piglets: A consequence of a disorganization of the perichondrial ossification groove of Ranvier. Can J Comp Med. 1984;48:414-419.
  4. Olson EJ, Carlson CS. Bones, Joints, Tendons, and Ligaments. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017:1005-1007.
  5. Slovak JE, Gilmour LJ, Miles KG. What is your diagnosis? Idiopathic calvarial hyperkeratosis. J Am Vet Med Assoc. 2015 Jun 1;246(11):1187.
  6. Snook SS, King NW. Familial infantile cortical hyperostosis (Caffey's disease) in rhesus monkeys (Macaca mulatta). Vet Pathol. 1989;26(3):274-277.


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