Serendipity in teaching pig health; a case of cystic hygroma in a suckling pig

1Utrecht

2Royal

Background:

Identification of rare cases relies on recognition of the unknown and ability to observe, define, investigate and evaluate the findings. Many non-infectious diseases can occur multiple species, but may have been scarcely described in pigs. Awareness is important for recognition by other clinicians as well as for surveillance of potentially emerging diseases. For example, cystic hygromas (lymphangiomas) are rarely reported in various animal species, including humans.

A hygroma is defined as a benign congenital malformation of the lymphatic drainage system, presenting itself as a mass consisting of multiple cysts of various sizes with a watery content

This case report presents findings about a single pig that was identified by students of veterinary medicine during a regular health check.

Case presentation:

Clinical investigations:

A 3.5-week-old, farm-bred, female crossbred piglet of ±4 kg was presented with a mass cranial to the right femur (Fig. 1A). The mass was approximately 10 × 7 cm in diameter, soft, painless, with a clear irregular surface and clear demarcation from the surrounding unaffected tissue, the overlying skin was intact. Clinical parameters of the pig were not divergent. The clinical differential diagnosis included abscessation, hernia, posttraumatic hematoma, and neoplasms.

Explorative ultrasonographic examination:

Using a 5.0 MHz sector probe, ultrasound investigations revealed a fluid-filled multi-cystic structure with thin internal septations (Fig. 1B).

Post-mortem investigations:

The piglet was euthanized and submitted for post-mortem examination in accordance with local legislation and welfare guidelines. The mass (Fig. 2A) was characterized by a few thinwalled cysts, containing clear yellow serous fluid (Fig. 1C). Histologically, the central cavity was lined by a single layer of squamous cells, supported by a thick fibrous stroma (Fig. 2B & Fig. 2C). On immunohistochemistry, scattered lining cells were weakly positive for Factor-VIII (Fig. 2D), suggesting their possible endothelial origin.

Survey:

An informal request was sent to Dutch pig practitioners by GD-Veekijker through social media to obtain information about similar cases. One suspicious case was reported but a hygroma was ruled out subsequently. No other cases were reported nor identified.

Conclusions:

The case report underscores the importance of careful diagnostics when confronted with a mass in pigs. Not all masses are inflammatory or neoplastic and may have an different origin. A OneHealth cross-species approach and specialist knowledge are valuable assets to set the correct diagnosis. This report contributes to raising awareness on hygromas in pigs that allows early identification in life so that appropriate care can be provided. The case report attributes knowledge on hygromas in general, as better understanding of pathologic features, the aetiology and appropriate treatment are needed, in all species.

Acknowledgements

3Utrecht University, Faculty of Veterinary Medicine, Department of Biomolecular Health Sciences, Veterinary Pathology Diagnostic Centre, Utrecht, the Netherlands t.tobias@gdanimalhealth.com

The animal care takers and colleagues of the Veterinary Pathology Diagnostic Centre are greatly acknowledged for their assistance in collecting information and post-mortem examinations.