JPC SYSTEMIC PATHOLOGY
Musculoskeletal System
April 2019
M-P03 (NP)

Signalment (JPC #2050449):  Three-year-old steer

HISTORY:  Cheek muscle taken at slaughter

HISTOPATHOLOGIC DESCRIPTION:  Skeletal muscle:  Focally separating skeletal muscle fibers is a longitudinal section of a cestode larva (cysticercus) within a 2x1 mm parasitic cyst with a thin, 4 um wide, eosinophilic tegument, a lacy, fibrillar eosinophilic parenchyma, and scattered 5 um diameter, basophilic, calcareous corpuscles.  A fibrous capsule, infiltrated by numerous lymphocytes, eosinophils and hemosiderin-laden macrophages, surrounds the cyst.  Inflammatory cells extend into the adjacent connective tissue and expand the endomysial and perimysial layers of  muscle fibers.  Scattered within the remaining muscle are small aggregates of lymphocytes, macrophages and neutrophils.  Multifocal myocytes are pale and swollen (degeneration), or intensely eosinophilic with loss of cross striations (necrosis).

MORPHOLOGIC DIAGNOSIS:  Skeletal muscle:  Cysticercus with mild muscle degeneration and chronic eosinophilic myositis, breed unspecified, bovine.

ETIOLOGIC DIAGNOSIS:  Cysticercal myositis

CAUSE:  Cysticercus bovis

CONDITION:  Beef measles; measly beef

GENERAL DISCUSSION:

PATHOGENESIS:

LIFE CYCLE: 

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS:

ADDITIONAL DIAGNOSTIC TESTS:

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY:

Tapeworm

Definitive Host

Metacestode

IH

Anatomic location

 T. solium

Man

Cysticercus cellulosae

Pig, man

Muscle

T. hydatigena

Dogs, carnivores

Cysticerus tenuicollis

Sheep, other ruminants, pigs

Omentum, mesentery

T. ovis

Dogs, carnivores

Cysticercus ovis

Sheep, goats

Muscle

T. krabbei

Wild carnivores

Cysticercus tarandi

Reindeer, other ruminants

Muscle

T. pisiformis

Dogs, carnivores

Cysticercus pisiformis

Rabbits, hares

Serosa

T. taeniformis

Cats, other felids

*Cysticercus fasciolaris

Rodents

Liver

T. multiceps

Dogs, carnivores

**Coenurus cerebralis

Sheep, goats

Brain, spinal cord

T. serialis

Dog, fox

Coenurus serialis

Lagomorphs

Subcutis and intramuscular

*Hepatic fibrosis and granulomatous inflammation which may progress to fibrosarcoma is associated with Strobilocercus fasciolaris in rat livers; additional lesions include gastric and intestinal hyperplasia

**Infection of Coenurus cerebralis in sheep is known as “gid”

REFERENCES:

  1. Bowman DD. In: Bowman DD, ed. Georgis’ Parasitology for Veterinarians. 10th ed. St. Louis, MO: Saunders Elsevier; 2013:145-147.
  2. Cooper BJ, Valentine BA. Muscle and tendon. In: Maxie MG, ed. Jubb, Kennedy and Palmer’s Pathology of Domestic Animals. Vol 1. 6th ed.  Louis, MO: Elsevier; 2016:239-240.
  3. Gardiner CH, Poyton SL. An Atlas of Metazoan Parasites in Animal Tissues. Washington, DC: American Registry of Pathology; 2006:50-55.
  4. Lagapa JT, Oku Y, Kamiya M. Immunohistochemical characterization of cellular proliferation in small intestinal hyperplasia of rats with hepatic Strobilocercus fasciolaris J Comp Path. 2008; 139:34-39.
  5. Lagapa JT, Oku Y, Kamiya M. Taenia taeniaeformis: Colonic hyperplasia in heavily infected rats. Exp Parasitol. 2008; 120:417-420.
  6. Valentine BA. Skeletal muscle. In: McGavin MD, Zachary JF, eds. Pathologic Basis of Veterinary Disease. 6th ed. St Louis, MO: Elsevier; 2017:923.e1.
  7. Yi JY, et al. Prevalence of hepatic parasites in Korean wild rats (Rattus norvegicus) and their association with pulmonary arteriolar medial hypertrophy. Vet Pathol. 2010; 47(2):292-297.


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