In a 2 year old sow carcass multiple whitish rounded masses were observed in the lung showing a multifocal and widespread distribution. The diameter of the masses varied from 4 mm to 15 cm. When sectioned a whitish coloration was seen.

Microscopically these masses corresponded to an intense inflammatory infiltrate composed mostly by macrophages, scant eosinophils and a few multinucleated giant cells. Necrosis was not present. Sectionsof the mediastinal lymph node were also studied andthe same type of inflammation was fouind in them. It is therefore a granulomatous proliferative pneumonia and lymphadenitis.

Unfortunately the final cause of such an inflammatory reaction could not be determined. The tests performed included :

  • Ruling out a mycobacteriosis by Ziehl-Neelsen staining (Negative) and PCR against M.tuberculosiscomplex (Negative) and mycobacteria culture (Negative).
  • The presence of fungal structures was also discarded by means of a Grocott staining (Negative).
  • No presence of gram positive bacteria could be observed with Gram staining (Negative) and through standard microbiological culture (Negative).
  • Morphologically , it was also ruled that it was a process associated to parasites or a neoplasia.

If anyone has encountered similar cases or has an idea of what can cause this type of lesion, you are welcome to share it in the comments section at the end of this post.

The lesion affects all lung lobes and mediastinal lymph nodes.

The lesion affects all lung lobes and mediastinal lymph nodes.

When sectioned the masses have a whitish homogeneous colouration.

When sectioned the masses have a whitish homogeneous colouration.

Under the microscope one can observe a granulomatous inflammatory reaction with numerous multinucleated giant cells such as the one of the image.

Under the microscope one can observe a granulomatous inflammatory reaction with numerous multinucleated giant cells such as the one of the image.