JPC SYSTEMIC PATHOLOGY
Hemolymphatic System
March 2018
H-B10

SIGNALMENT (JPC Accession #3134342):  7-month-old spayed, female Maltese mix dog

HISTORY:  This dog presented with a 5-day history of lethargy and 2-day history of anorexia and vomiting. The dog was obtunded and laterally recumbent on physical exam.  The dog was hypothermic (96.8F), with 8-10% dehydration. Following rehydration, to dog developed watery melena and vomited frank blood.

HISTOPATHOLOGIC DESCRIPTION: 

SLIDE A: Lymph node: There is lymphocyte loss and diffusely, lymph node follicular and parafollicular architecture is effaced by numerous macrophages, low to moderate numbers of neutrophils, scattered hemorrhage with fibrin, increased clear space (edema), and necrotic cellular debris. Macrophages have abundant eosinophilic cytoplasm and often contain 1um coccoid rickettsial organisms, erythrocytes, or cellular debris. The subcapsular, cortical, and medullary sinuses and are diffusely expanded by similar population of macrophages admixed with edema and hemorrhage.  Sinus macrophages often demonstrate erythrophagocytosis.

Duodenum: Embedded within crypts of the mucosa, there is an adult trematode that measures approximately 400 um in diameter, has a spiny, eosinophilic tegument, a muscular oral sucker, and is filled with spongy parenchyma that contains vitellaria, testes with germ cells and sperm, and thin-walled, 3-5 um, refractile eggs that contains a miracidium.  The surrounding mucosa and lamina propria are expanded by lymphocytes, plasma cells and macrophages that fill the lamina propria and separate crypts, which are markedly proliferative, causing an overall thickening of the mucosa.  Crypts are mildly expanded and filled with eosinophilic cellular and karyorrhectic debris (necrosis). Villi are blunted and fused and denuded of mucosal epithelium.  The mucosal epithelium is regenerative with some cells exhibiting large, vesicular nuclei.  Occasionally, epithelial cells and macrophages contain lightly basophilic, 1um coccoid rickettsial organisms within their cytoplasm (rickettsiae).

MORPHOLOGIC DIAGNOSIS:  Lymph node: Lymphadenitis, granulomatous and necrotizing, diffuse, severe, with lymphocyte loss and intracellular rickettsiae, Maltese mix, canine.

Duodenum: Enteritis, granulomatous and lymphoplasmacytic, multifocal, moderate, with intrahistiocytic rickettsiae.

Duodenum: Adult trematode (Nanophyetus salmincola).

SLIDE B: (Giemsa) Lymph node: Diffusely, there are metachromatically staining (purple) 1um coccoid organisms filling the cytoplasm of macrophages.

Duodenum: Multifocally, there are metachromatically staining 1um coccoid organisms within the cytoplasm of epithelial cells and macrophages within the lamina propria.

SLIDE C: Cranial section of salmon fingerling: Multifocally expanding skeletal muscle, gill lamellae, and spleen are numerous, up to 125 um in diameter, cross sections of trematode metacercariae which compress adjacent parenchyma, characterized by a 3 um bright eosinophilic cyst wall, parenchyma, and a single sucker.

MORPHOLOGIC DIAGNOSIS: Skeletal muscle; gill lamellae, kidney: Trematode, numerous, salmon, piscine.

ETIOLOGIC DIAGNOSIS:  Neorickettsial lymphadenitis and splenitis

ETIOLOGY:  Neorickettsia helminthoeca

CONDITION:  Salmon poisoning disease (SPD); Canine neorickettsiosis

GENERAL:

PATHOGENESIS:

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS:

ADDITIONAL DIAGNOSTIC TESTS:

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY:

Pathogen

Host

Vector

Target cells

Disease

Aegyptianella pullorum

Poultry

Ticks

Erythrocytes

Aegyptianellosis

Anaplasma bovis

Cattle

Ticks

Erythrocytes

Bovine anaplasmosis

Aegyptianella pullorum

Poultry

Ticks

Monocytes, macrophages

Aegyptianellosis

Anaplasma marginale

Ruminants

Ticks

Erythrocytes

Anaplasmosis

Anaplasma ovis

Sheep, goats

Ticks

Erythrocytes

Anaplasmosis

Anaplasma phagocytophilum

*Formerly Ehrlichia equi and Ehrlichia phagocytophila

Ruminants, horses, humans

Ticks

Granulocytes

Tick-borne fever, equine and human granulocytic ehrlichiosis

Anaplasma platys

Dogs

Ticks?

Platelets

Canine cyclic thrombocytopenia

Ehrlichia canis

Dogs

Ticks

Monocytes, macrophages

Canine monocytic ehrlichiosis

Ehrlichia ewingii

Dogs

Ticks

Granulocytes

Canine granulocytic ehrlichiosis

Ehrlicia (formerly Cowdria) ruminantium

Ruminants

Ticks

Granulocytes

Heartwater

Ehrlichia ondiri

Cattle

Ticks?

Granulocytes, monocytes

Bovine petechial fever

Ehrlichia ovina

Sheep

Ticks

Monocytes, macrophages

Ovine ehrlichiosis

Neorickettsia elokominica

Dogs, bears, raccoons

Flukes

Monocytes, macrophages, lymphoid cells

Elokomin fluke fever

Neorickettsia helminthoeca

Dogs, bears

Flukes

Monocytes, macrophages, lymphoid cells

Salmon poisoning disease

Neorickettsia risticii

Horses

Flukes

Monocytes, intestinal epithelial cells, mast cells

Potomac horse fever

Rickettsia ricketsii

Dogs

Ticks

Endothelial cells

Rocky Mountain spotted fever

REFERENCES:

  1. Bowman DD. Georgi’s Parasitology for Veterinarians. 10th ed. St. Louis, MO: Elsevier Saunders; 2014:131.
  2. Gardiner CH, Poynton SL. An Atlas of Metazoan Parasites in Animal Tissues. Washington, DC: Armed Forces Institute of Pathology, American Registry of Pathology; 2006:46-49.
  3. Gelberg HB. Alimentary system and the peritoneum, omentum, mesentery, and peritoneal cavity. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017:408.
  4. 4. Gorham JR, Foreyt WJ, Sykes JE. Neorickettsial helminthoeca infection (salmon poisoning disease). In: Green CE, ed. Infectious Diseases of the Dog and Cat. 4th St. Louis, MO: Elsevier Saunders; 2012:220-4.
  5. Johns JL. Immune-mediated and other nonneoplastic white blood cell disorders. In: Ettinger SJ, Feldman EC, Cote E, eds. Textbook of Veterinary Internal Medicine. Vol 1. 8th ed. St. Louis, MO: Elsevier; 2017:860.
  6. Quinn PJ, Markey BK, Leonard FC, FitzPatrick ES, Fanning S, Hartigan PJ. Rickettsiales and Coxiella burnetii. In: Veterinary Microbiology and Microbial Disease. 2nd ed. Ames, Iowa: Blackwell Science Ltd; 2011: Kindle edition. 
  7. Sykes JE. Ehrlichiosis, anaplasmosis, Rocky Mountain spotted fever, and neorickettsiosis. In: Ettinger SJ, Feldman EC, Cote E, eds. Textbook of Veterinary Internal Medicine. Vol 1. 8th ed. St. Louis, MO: Elsevier; 2017:949.
  8. Sykes JE, Marks SL, Mapes S, et al. Salmon Poisoning Disease in dogs: 29 cases. J Vet Intern Med. 2010;24:504-513.
  9. Uzal FA, Plattner BL, Hostetter JM. Alimentary system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 2. 6th ed. St. Louis, MO: Elsevier; 2016:225-226.
  10. Valli VEO, Kiupel M, Bienzle D. Hemopoietic system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 3. 6th ed. St. Louis, MO: Elsevier; 2016:148-149.

 


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