TVMDL Pathologist Josué Díaz-Delgado, DVM, MS, PhD, DACVP was part of two groups recently published in marine pathology journals.
Abstracts for each article are below.
Facial Squamous Cell Carcinoma and Abdominal Peripheral Nerve Sheath Tumour with Rhabdomyoblastic Differentiation in a Rough-toothed Dolphin (Steno bredanensis)
We report the pathological features of a facial squamous cell carcinoma (SCC) and an abdominal peripheral nerve sheath tumour (PNST) with rhabdomyoblastic differentiation in an aged free-ranging rough-toothed dolphin (Steno bredanensis). The animal was found stranded dead in poor body condition. On external examination, there was a 25 × 7 × 3 cm extensively ulcerated area on the right maxillary region of the rostrum, involving the oral mucocutaneous junction with prominent nodular edges, severe soft tissue loss and extensive maxillary and premaxillary bone lysis. On abdominal dissection, a 5 × 4 × 3.5 cm pale tan to red, raised mass expanded the inner aspect of the right transverse abdominis muscle. Microscopically, the aggressive facial lesion was an acantholytic SCC with extensive osteolysis; there was no evidence of metastasis in the tissues examined. The abdominal mass had cytohistomorphological features compatible with a localized PNST, including whorling, Antoni A and Antoni B areas and Verocay bodies intermixed with rhabdomyoblastic components, as suggested by phosphotungstic acid haematoxylin stain. This neoplasm was locally infiltrative, yet no metastases were observed in the tissues examined. No immunohistochemical investigations could be performed due to lack of tissue availability. Total DNA from the formalin-fixed and paraffin wax-embedded SCC was extracted and tested by polymerase chain reaction for herpesvirus and papillomavirus genetic material. There was no amplification for either of these genera. Other pathological findings observed in this animal were related to the ‘live-stranding stress response’. The severity and extent of the facial SCC likely related to anorexia and poor body condition and might have played a role in the stranding and death of this dolphin. These two tumour subtypes add to the relatively uncommon reports of neoplasia in cetaceans. Specifically, these appear to be the first neoplasia records for rough-toothed dolphins, including the first documentation of a PNST with features compatible with rhabdomyoblastic differentiation in a marine mammal.
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“Non-archetypal Toxoplasma gondii in Balaenoptera edeni” Fatal systemic toxoplasmosis by a novel non-archetypal Toxoplasma gondii in a Bryde’s whale (Balaenoptera edeni)
We report the results of pathological, immunohistochemical and molecular genotyping analyses in a Bryde’s whale (Balaenoptera edeni) with disseminated toxoplasmosis. A 10.7 m-long, adult, male Bryde’s whale in poor body condition stranded alive in August 21st, 2018, in ‘Pontal do Ipiranga’, Linhares, Espirito Santo state (Brazil). The animal died shortly after stranding and was promptly autopsied. The main gross findings were: diffuse axial skeletal muscle atrophy; generalized congestion, petechiation and ecchymoses; necrotizing splenitis, hepatitis, myocarditis, pneumonia and lymphadenitis (prescapular, pulmonary, mediastinal, mesenteric); bilateral scapulohumeral hemarthros; and severe pulmonary edema. Microscopic examination confirmed the aforementioned diagnoses, featuring a histopathologic signature characterized by multisystemic necrotizing inflammation with vasculitis and disseminated intravascular coagulation, thrombosis and numerous intralesional protozoal cysts and extracellular tachyzoites morphologically compatible with Toxoplasma gondii. Immunohistochemical and polymerase chain reaction (PCR) analysis targeting a repetitive 529 bp DNA fragment of T. gondii confirmed toxoplasmosis in the liver, spleen, lung and lymph nodes. PCR-restriction fragment length polymorphism (RFLP) analysis using 11 markers identified a new non-archetypal genotype, ToxoDB-RFLP genotype #300. Further, the genotyping by microsatellite technique employed 15 markers and confirmed a unique non-archetypal T. gondii strain, designated PS-TgBaledBrES1. These novel results add to the diversity of this parasite in the world and to the scarce data on T. gondii genotype distribution in cetaceans, represent the first record of toxoplasmosis in a Bryde’s whale and set the baseline knowledge for future research on T. gondii genotyping research in marine mammals from South America.
Read the full article here.
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