Male Zebrafish

SIGNALMENT: (age, breed, sex, species, and scientific name) 

1. 5Z6/4A-37; 11 mo at necropsy, male, zebrafish Danio rerio, Florida wild-type line
2. ZJS 43/3-1; 12.5 mo at necropsy, male, zebrafish Danio rerio, Tuebingen long fin (TL) line which is a double mutant with spotted skin and long fins (leopard; long fin)
3. MK; 18 mo at necropsy, zebrafish Danio rerio, Tuebingen long fin (TL) line which is a double mutant with spotted skin and long fins (leopard; long fin)

TREATMENT PROTOCOL (including test compound identification, dose, and class of molecule):

1. 5Z6/4A-37 fed Compound X at 100 ppm for 4 weeks beginning at 2 months of age
2. ZJS 43/3-1 untreated fish from prospective study of spontaneous tumors, sacrificed due to large mass on nose. (Lesions for this fish are similar to 5Z6/4A-37, so images are not presented for this fish.)
3. MK diagnostic case submitted to the diagnostic service coordinated by the Zebrafish International Resource Center at the University of Oregon. Untreated broodstock with spontaneous mass on nose.

GROSS PATHOLOGY:
Typical gross lesion is a soft, white, smooth, polypoid mass protruding from the naris unilaterally.

LABORATORY RESULTS: (clinical pathology, microbiology, etc…)

No ancillary tests conducted.

What's Your Diagnosis? Provide your possible etiologies in the comment section.

Tissue from 5Z6/4A-37 fish. Gross lesion showing soft white, polypoid mass 7x4x3 mm protruding from naris. 

4X. H&E. Tissue from MK fish. Mass protruding from naris.  

10X. H&E stain. Tissue from MK fish. Higher magnification of mass.

25X. H&E.  Tissue from MK fish. Higher magnification of mass.

4X. H&E.  Tissue from 5Z6/4A-37 fish. Mass protruding from naris.

10X. H&E. Tissue from 5Z6/4A-37 fish. Mass protruding from naris.

25X. H&E. Tissue from 5Z6/4A-37 fish. Mass protruding from naris.

40X. H&E.  Tissue from 5Z6/4A-37 fish. Mass protruding from naris.

S100 IHC. Tissue from 5Z6/4A-37fish. Mass.