1998-1999 Wednesday Slide Conference 6
Diagnoses

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Case 1 Contrib# 98-040 AFIP# 2638214 canine

Case 6-1. Gross photo. Adjacent to the excised spinal cord there is a hemorrhagic, multinodular mass (5x9cm) attached to and surrounding 3-4 spinal nerves. This mass encompasses another longitudinally oriented structure which may represent another nerve or a large blood vessel (aorta?).

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Case 6-1. Spinal cord. This section (2x obj) of spinal cord is expanded and replaced by an infiltrative mass supported by a prominant fibrovascular stroma. Tumor cells are quite pleomorphic, and characterized by oval to round cells which may be closely associated or individualized, and include scattered elongated cells separating the neuropil. Nuclei are hyperchromatic.

Morphologic Diagnosis: Spinal cord: Primitive neuroectodermal tumor.

Etiology: Unknown

Disease: Primitive neuroectodermal tumor

 

Case 2 Contrib# 97N172 AFIP# 2638859 rabbit

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Case 6-2. Oral mucosa. Beneath the mucosal epithelium there is a multinodular mass lined by columnar epithelial cells (arranged in palisades) which surround areas of loose stellate reticulum. Occasional foci of mineralized debris and squamous epithelial cells are found within epithelium lined cystic spaces.

Morphologic Diagnosis: Buccal mucosa: Ameloblastoma.

Etiology: Unknown

Disease: Ameloblastoma

 

Case 3 Contrib# 98-2048 AFIP# 2641082 canine

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Case 6-3. Liver. Large areas of liver parenchyma are expanded, separated, and replaced by a pleocellular infiltrate. There is preservation of the major vessels and some bile ducts, but in the center of this mass there is effacement of hepatic plates.

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Case 6-3. Liver. Infiltrating cells include abundant eosinophils with lesser numbers of large pleomorphic round cells admixed with fewer small lymphocytes. Occasional large atypical cells are associated with numerous 2-3u small basophilic bodies (lymphoglandular bodies?). A residual bile duct is at the lower left and strip of brown pigment bearing hepatocytes are at the upper right.

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Case 6-3 . Immunohistochemical staining for CD3 antigen reveals that positively staining T cells with small to medium lymphocyte morphologies are scattered throughout the tumor and admixed with large atypical cells (which do not usually stain).

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Case 6-3 . Immunohistochemical staining for CD45RA antigen is positive in large atypical cells bearing one or more prominant nucleoli, but staining is generally negative in smaller cells with lymphocyte morphology.

Morphologic Diagnosis: Liver: Malignant B-cell lymphoma, T-cell rich, with tissue eosinophilia.

Etiology: Unknown

Disease: B-cell lymphoma

 

Case 4 Contrib# 556-98 AFIP# 2643249 feline

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Case 6-4. Lung. There is marked compression and infiltration of alveoli by a cellular infiltrate. Bronchi in the lower left contains an amphophilic exudate. Pleural connective tissue in the upper right is coated by a heavy, partly detached cellular exudate.

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Case 6-4. Lung, pleura. Exudate covering the pleura is composed of abundant plump epithelioid macrophages which occasionally contain variable numbers of 1x3u eosinophilic bodies interpreted as bacilli. Moderate numbers of neutrophils and fewer lymphocytes and plasma cells are scattered throughout this exudate.

Morphologic Diagnosis: Lung: Pleuritis, pyogranulomatous, diffuse, severe, with multifocal pyogranulomatous pneumonia, diffuse atelectasis, and numerous intrahistiocytic gram-positive coccobacilli.

Etiology: Rhodococcus equi

Disease: Rhodococcal infection

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