JPC SYSTEMIC PATHOLOGY
DIGESTIVE SYSTEM
September 2018
D-N10 (NP)

Signalment (JPC #2749934):  9-year-old mixed breed dog

HISTORY:  Rectal mass

HISTOPATHOLOGIC DESCRIPTION:  Rectum:  Expanding the submucosa and elevating the overlying ulcerated mucosa is a 1 cm diameter, unencapsulated, well-circumscribed, densely cellular neoplasm composed of sheets and cords of round cells separated by a fine network of capillaries.  Neoplastic cells have variably distinct cell borders and moderate amounts of eosinophilic, granular cytoplasm.  Nuclei are eccentrically located, irregularly round to oval, occasionally indented with finely clumped chromatin and have one variably prominent nucleolus.  Nuclei often contain cytoplasmic invaginations.   There is moderate anisocytosis and anisokaryosis with occasional megalokaryosis and rare binucleate cells.  Mitotic figures average 3 per 10 HPF. Admixed with neoplastic cells are multiple foci of hemorrhage, fibrin, edema and fibrosis, and single cell necrosis.  The overlying mucosa is eroded with multifocal dilated crypts and a focally extensive area (5mm) of ulceration that is replaced by hemorrhage, fibrin, and edema and many neutrophils. Multifocally, the lamina propria is expanded by moderate numbers of plasma cells and neutrophils along with mild hemorrhage, fibrin, and edema. Adjacent submucosa contains hemorrhage, fibrin, and edema with moderate numbers of plasma cells, fewer lymphocytes and hemosiderin-laden macrophages, and rare neutrophils.

MORPHOLOGIC DIAGNOSIS:  Rectum:  Plasmacytoma, mixed breed dog, canine.

CONDITION:  Extramedullary plasmacytoma (EMP)

SYNONYM:  Plasma cell tumor; Plasmacytoma

GENERAL DISCUSSION:

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS:

ULTRASTRUCTURE: 

Features of plasma cells:

ADDITIONAL DIAGNOSTIC TESTS: 

DIFFERENTIAL DIAGNOSIS:

 COMPARATIVE PATHOLOGY:

REFERENCES:

  1. Boes KM, Durham AC. Bone marrow, blood cells, and the lymphoid/lymphatic system. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017:795.
  2. Clancy CS, Roug A, Armien AG, Van Wettere AJ. Intracerebral malignant plasmacytoma in a mule deer (Odocoileus hemionus). J Comp Path. 2016; 154:268-271.
  3. Ehrensing G, Craig LE. Intravascular neoplastic cells in canine cutaneous plasmacytomas. J Vet Diag Invest. 2018; 30(2):329-332.
  4. Munday JS, Lohr CV, Kiupel M. Tumors of the alimentary tract. In: Meuten D, ed. Tumors in Domestic Animals. 5th ed. Ames, IA: John Wiley & Sons; 2017:171-172,218-225,577.
  5. Sykes SE, Byfield V, Sullivan L, et al. Feline respiratory extramedullary plasmacytoma with lymph node metastasis and intrahistiocytic amyloid. J Comp Path. 2017; 156:173-177.
  6. 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; 2016:27-28.
  7. Valli VEO, Kiupel M, Bienzle D et al. Hematopoietic system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer"s Pathology of Domestic Animals. Vol 3. 6th ed. St. Louis, MO: Elsevier; 2016:226-228.


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