In a male, cross breed, 6 months old, pig carcass multiple, multifocal,  erythematous lesions were observed some of which  with concentric circles morphology. Generalized lymphadenopathy was also observed with increased size and redness of the lymph nodes.

Samples submitted for histopathology were taken after scalding, precluding an appropriate assessment of the histological lesions in the epidermis and the superficial dermis due to the artifacts caused by this process. In the deeper dermis,  perivascular and periadnexal dermatitis was observed. The lymph nodes were hyperplastic and with abundant presence of eosinophilic polymorphonuclear leukocytes. The kidneys showed no obvious lesions.

Despite having a very characteristic lesional pattern the aetiology could not be determined. A while ago another case of Mystery dermatitis in a pig carcass was submitted, of which the ethiology could not be determined, in that case the lesions were radial.

The differential diagnosis could include:

  • Porcine Dermatitis and nephropathy syndrome (PDNS): histopathological study of the kidneys ruled this one out, which was the main suspicion of the inspectors who submitted the case.
  • Pityriasis rosea: swine juvenile psoriasiform pustular dermatitis. It seems one of the most probable differentials.
  • Dermatophytosis (ringworm).
  • Erysipelas: despite  the characteristic rhomboid morphology of lesions was not observed.

In human medicine figured erythemas are described, some of which (eg erythema annulare centrifugum) are reminiscent of images we see in this pig carcass. The causes can be varied: from primary disease of the skin (tinea, urticaria …) to systemic diseases (bacterial infections, neoplasms …) presenting this lesion.

Again, if any of you have seen such a lesion, we encourage you to discuss this in the comments section at the end of this post.

Lesions a l’aspecte ventral de la canal.

Lesions on the ventral aspect of the carcass.

Detall de les lesions a la part dorsal, que mostren un particular patró concèntric.

Detail of the  lesions on the dorsal aspect, showing a particular concentric pattern.

Augment de mida i envermelliment dels nòduls limfàtics inguinals superficials.

Increased size and redness of the superficial inguinal lymph nodes.