The condition in human medicine is associated with a large variety of diseases and clinical conditions in which the loss of intestinal mucosal integrity and/or luminal high pressure usually occur. PCI can be classified in terms of pathogenesis as primary (idiopathic without any obvious cause) or secondary to a wide variety of conditions including; intestinal necrosis, intestinal obstruction, mucosal disruption, increased mucosal permeability, and pulmonary disease ¹.

There are mainly 4 sources of gas in the intestinal wall; gas escapes through any disruption of the mucosa, pulmonary gas released from the ruptured alveoli, gas production of some bacteria and excessive fermentation due to maldigestion ⁶.

PCI is mostly asymptomatic, however, a spectrum of clinical signs including vomiting, abdominal distention, abdominal pain, diarrhea, constipation, and tenesmus was reported in dogs ^4,5.

This report presents morphological and immunohistochemical findings of a case of PCI in pig.

At necropsy, polyploid thin walled, gas filled cysts in serosal surface of small and large intestineum were seen. Their size of the lesions ranged from 1 mm to a few cm (Figure 1A and B). There was no any other remarkable morphological changes in internal organs or tissues macroscopically.

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Figure 1: A and B. Subserosal gaseous cysts (arrows) with thin wall, varying size, in subserosal surface of small and large intestineum. C. Microscopic appearance of the cyst wall (arrow). D. Positive immunoreaction to the endothelial cells to podoplanin (arrow).

The tissue samples from small and large intestines, liver, lung, brain, and pancreas were fixed in 10% formalin solution. Paraffin blocks prepared by routine methods were cut approximately 5 μm in thickness and stained with hematoxylin-eosin (H&E). Selected sections were stained by podoplanin (Mouse monoclonal, clone D2-40 Dako, Glostrup, Denmark, 1:400) by avidin-biotin peroxidase.

Histopathological examination showed that the cystic spaces were lined by endothelial cells. There was no inflammatory reacrion in stroma (Figure 1C).

Immunohistochemical examinations indicated that there was a strong immunopositivity for the podoplanin on the inside of the cystic wall. On higher magnification, the podoplanin-expressing cells were identified to be linearly lined spindle cells (Figure 1D).

The etiology of the present case remains obscure, however based on anamnesis of animal quarrel, the present case of PCI speculatively might be resulted from the translocation of gas as a consequence of the increased mucosal permeability secondary to abdominal trauma. Although there were no skin lesions indicating trauma or ulcer, erosion in intestinal mucosa, blunt trauma might be responsible for the occurrence of the lesions. Similar to present report, a case of posttraumatic pneumatosis intestinalis was reported in human infant ⁸. However host factors such as carbohydrate intolerance may also have a significant role either alone or in combination with other factors in pigs and humans ⁹.

Overall, the present case report clearly demonstrates the cystic structures are dilated lymphatics expressing podoplanin in PCI of a pig.

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