PCR technique detection of Leishmania spp. but not Mycobacterium spp. in canine cutaneous 'sterile' pyogranuloma/granuloma syndrome

Cutaneous 'sterile' pyogranuloma/granuloma syndrome (SPGS) is an uncommon canine skin disorder of unknown aetiopathogenesis. Histopathological findings and failure to demonstrate an aetiologic agent are suggestive of this syndrome. Nevertheless, it has been hypothesized that SPGS may be related to an immune response against persistent endogenous or exogenous antigens. The presence of Leishmania and Mycobacterium organisms was investigated by polymerase chain reaction (PCR) techniques in 46 canine skin samples histopathologically diagnosed as SPGS. Concomitantly, an immunohistochemical technique for Leishmania detection was applied on the same samples and the results were compared with those from PCR. The PCR technique yielded positive results for Leishmania spp. in 21 out of 46 skin samples. The results of immunohistochemical techniques were identical to those obtained by PCR. The PCR technique gave negative results for Mycobacterium spp. in all the samples examined. These results suggest the importance of looking for Leishmania spp. in skin biopsies with histopathological findings consistent with the diagnosis of SPGS.