A 3-week-old suckling piglet spontaneously died after septicemic colibacillosis. At postmortem examination, bulging and ulcerated lesions were seen, affecting the oral mucosa on the inner surface of the lower lip. After histopathological investigation, the diagnosis of congenital oral squamous cell carcinoma was made. To the best of our knowledge, this is the first case of congenital oral squamous cell carcinoma ever described. A relationship has been shown or suggested between papillomavirus infection and oral squamous cell carcinoma in humans and animals. However, next-generation sequencing study did not demonstrate any papillomavirus sequences in the case reported herein.
Cancer is widely recognized as a major cause of morbidity and mortality in small companion animals [
The event occurred in a small farrow-to-finish pig herd located in central Italy, the breeding stock consisting of 70 sows (Landrace x Large White x Duroc) and 2 boars (Mora Romagnola, an Italian local breed). All pigs were routinely vaccinated against Aujeszky’s disease (Aujeszky A-Suivax GI, Fatro, Italy), according to the Italian law. In addition, sows were vaccinated against colibacillosis and clostridiosis (Suiseng, Hipra, Spain), while piglets were vaccinated 15 days from birth against porcine circovirus type 2,
In May 2020, the herd experienced a severe episode of colibacillosis in suckling piglets, with a relevant increase of mortality. Several piglets were autopsied for diagnostic purposes. Among them, a 3-week-old piglet was examined. The animal showed a moderate body condition. At necropsy, acute enteritis, systemic enlargement and hyperaemia of lymph nodes, mild splenomegaly, pulmonary oedema, and disseminated petechiae on the visceral pleura, as well as on the external surface of the kidneys, were seen. On the basis of the postmortem pathological findings, septicemia was suspected. Bacteriological investigation yielded the isolation of
Notably, bulging and ulcerated lesions were also seen, affecting the oral mucosa. The largest lesion was seen on the inner surface of the lower lip, close to the right second and third incisors (Figure
Suckling piglet. Gross pathology. A large lesion (
Suckling piglet. Oral lesion. Histopathology. Cords and islands of neoplastic cells almost entirely infiltrate the lamina propria of the oral mucosa (a). Inside the proliferation, neoplastic cells undergo keratinization and tend to arrange as concentric layers, thus forming a horn pearl draft (black asterisk). At this magnification, prominent nucleoli are also evident, as well as several mitotic figures (black arrowheads; (b)). H&E, original objective 10x (a) and 20x (b).
Suckling piglet. Oral lesion. Histopathology. At higher magnification, intercellular bridges can be easily appreciated (black arrowhead). Mitoses are also evident. H&E, original objective 40x.
Oral lesion. Scanning of the entire slide. This picture clearly shows that the neoplasm was very extensive in both width and depth (black dotted lines). The lesion widely infiltrated the lip thickness, excluding only a thin layer of skin (red head arrows) and the lip border (black head arrow).
On the basis of the above microscopic findings, taking into account that tumors are defined as congenital when detected in foetuses and newborns until 2 months of age [
Unfortunately, we did not sample any other tissues or organs; thus, we cannot rule out the presence of metastases. We nonetheless remark that no microscopic evidence existed regarding the presence of neoplastic emboli inside the lymphatic and blood vessels; furthermore, lesions resembling neoplasms were not grossly observed at postmortem examination.
Thereafter, an aliquot of the formalin-fixed tissue sample was submitted for an in-depth biomolecular investigation, in order to confirm/rule out the presence of papillomaviruses or, more in general, oncogenic viruses. To this aim, DNA was extracted by the Maxwell® RSC DNA FFPE Kit (Promega, Madison, WI), using the Maxwell 16 Instrument (Promega, Madison, WI), according to the manufacturer’s protocol. Genomic libraries were prepared by means of the Illumina DNA Prep (Illumina, San Diego, CA) and then sequenced on the MiniSeq Instrument (Illumina Inc.), using MiniSeq Mid Output Reagent Cartridge v2 (Illumina Inc.), 300 cycles, and standard 150 bp paired-end reads. Raw reads were trimmed by Trimmomatic [
Oral SCCs are commonly diagnosed in cats and dogs, much less frequently in horses and sporadically in sheep [
Two cases of oral SCC have been described thus far in pigs, both affecting aged pet pot-bellied pigs. The first case was observed in a 10-year-old female pig, and SCC appeared as an ulcerated mass which infiltrated the hard and soft palate and metastasized to the draining lymph node and to the lungs [
As reviewed in detail in a previous work, porcine congenital tumors are uncommon and mostly of mesenchymal origin. Despite their very low prevalence, some congenital tumors in pigs (i.e., melanomas and lymphomas) have been studied thoroughly as models in comparative oncology, because of their mode of inheritance [
On an interesting note, a report regarding newborn piglets in China showed a very high incidence of enzootic lingual papillomatosis (>100.000/year) [
Overall, infectious diseases represent the most relevant issue in the field of porcine health management, leading the diagnostic approach to mostly be focused on viral and bacterial pathogens, often by means of biomolecular tools. Histopathology is not routinely carried out for diagnostic purposes in farm animals, at least in the Italian context. In spite of this, the present case report highlights that microscopic investigation is always of value to integrate with other laboratory tests, allowing for a more correct understanding of misleading postmortem findings and providing more reliable data about the prevalence and the main features of cancer in the different animal species.
All data are included in the main text of the manuscript.
The authors declare that they have no conflicts of interest.
All authors participated in the investigation; G.M. wrote and prepared the original draft; G.M., A.R.T., and J.M.A. wrote, reviewed, and edited the manuscript; all authors have read and agreed to the published version of the manuscript.
We gratefully thank Prof. Laura Bongiovanni (D.V.M., Ph.D., Dipl. E.C.V.P.) and Prof. Giovanni Lanteri (D.V.M., Ph.D., Dipl. E.C.A.A.H.) for their kind and outstanding diagnostic support. Moreover, we gratefully thank Dr. Alfreda Tonelli for kindly revising the English format. The present study has been carried out in the framework of the Project “Demetra” (Dipartimenti di Eccellenza 2018–2022, CUP_C46C18000530001), funded by the Italian Ministry for Education, University and Research.