Paraparesis Caused by Vertebral Canal Leishmaniotic Granuloma in a Dog

Abstract

A 7-year-old male Shih Tzu was examined because of acute onset of abnormal gait in pelvic limbs. Physical examination revealed pain at the level of the lumbar spine, paraparesis, ataxia, and decreased postural reactions in pelvic limbs. Muscle tone was normal. Normal patellar and cranial tibial reflexes were normal but flexor reflex was mildly reduced in the left pelvic limb. The neuroanatomic diagnosis was a focal or diffuse lesion between T 3 -L 3 . Hematologic and serum biochemical analysis revealed severe anemia (RBC 3.9, HB, HCT 27.5,, and on the following day paraparesis and ataxia increased.Bone marrow biopsy performed under general anesthesia at the level of humerus head revealed a leishmaniasis infection, with a high presence of amastigotes. Bone marrow plasmacytosis was present and numerous histiocytes containing Leishmania spp. were evident. Leishmania spp. were detected extracellulary microscopically. IFA titre for Leishmania was 4320. PCR for Ehrlichia and Borrelia spp. were negative.An MRI study was performed with an open permanent magnet operating in 0.2 T (ESAOTE). The study included T1-weighted spin echo (SE) sequences [800/26/ 3; repetition time (TR) echo time (TE)], T2-weighted SE sequences (3000/100/1; TR/TE), gadoliniumdimeglumide (0.5 mmol/mL, GE Healthcare Omniscan, Paderno Dugnano, Milan, Italy) enhanced T1-weighted SE sequences (gadolinium chelate dose was 0.1 mmol/kg, IV), in the 3 orthogonal planes, and Gradient echo STIR sequences (1490/25/1; TR/TE/IR).The MRI revealed the presence of an extradural mass ventral to the spinal cord and lateralized to the left localized on the L 4 -L 5 intervertebral disk to the midbody of L 5 , displacing the spinal cord. The lesion was hyperintense on T1-weighted, T2-weighted, and STIR images, and had heterogeneous postconstrast enhancement (Fig 1).As neurological signs were rapidly progressing, surgery was performed to decompress the spinal cord by means of a left L 4 -L 5 hemilaminectomy, an ill-defined extradural mass, located ventrolaterally, was identified. The mass was yellow and hardly distinguishable from the epidural fat, neither encapsulated nor adhesive and with friable appearance. The diseased tissue was then removed and fixed in 10% buffered formalin.After surgery, cephalosporine (20 mg/kg PO q12h for 10 days) and prednisolone (0.5 mg/kg PO q12h for 5 days) were administered.The surgically removed tissue consisted of epidural fat tissue heavily infiltrated by macrophages, lymphocytes, plasma cells, and neutrophils. Proliferation of capillaries and scattered hemorrhages were also seen. The cytoplasm of many foamy macrophages contained multiple Leishmania amastigotes (Fig 2). The parasites were also identified free within the interstitium. The organisms were strongly labeled by immunohistochemical staining by the streptavidin-biotin immunohistochemical method with canine hyperimmune serum as the primary antibody.

Occurrence of Leishmania infantum in the central nervous system of naturally infected dogs: Parasite load, viability, co-infections and histological alterations

“…In addition, there was no evidence of co-infection with other pathogens in the CNS of this dog. Granulomatous inflammatory infiltration of the parasitized CNS by amastigote forms of Leishmania has also been reported by other authors [11, 15, 16, 35, 40]. Although amastigote forms were not detected in the CNS of the other dogs of this study, the participation of L .…”

“…The detection of amastigote forms of L . infantum in the CNS of dogs had only been described in Europe in rare reports of cases in the meninges [16], choroid plexus [11, 15], thalamus [11], spinal nerves [11], spinal canal granuloma [35], and spinal cord parenchyma [11]. …”

Leishmania amastigotes in the central nervous system of a naturally infected dog

“…However, a focal reaction cannot be ruled out because other cases with focal infection have been reported, such as that of extradural granuloma. 6 In summary, the authors report herein the presence of Leishmania spp. amastigotes in nervous tissue producing radiculoneuritis, myelitis, and meningoencephalitis.…”

“…However, amastigotes were only observed inside macrophages in the extradural granuloma and free in the interstitium. 6 Detection of amastigotes in nervous tissue is very difficult; over the course of many years in the authors' laboratory, the authors have diagnosed thousands of CL cases, and except for a case of systemic vasculitis, 17 the presence of other nervous lesions or Leishmania amastigotes in nervous tissue has never before been observed. In human leishmaniasis, CNS involvement is rare; it has been observed in immunosuppressed people as a consequence of extension of a contiguous infection, most often in the paranasal sinuses, and usually in conjunction with disseminated infection.…”

“…8,9,11,13 Because Leishmania antibody titers have been observed to be very similar in CSF and blood, some authors have suggested that antibodies found in CSF might be produced in lymphoid tissue from which the antibodies access the CNS. 8,11 A study published in 2011 6 reported a dog with paraparesis caused by a Leishmania extradural inflammatory granuloma in the vertebral canal, with extension to the epidural space and compression of the spinal cord. However, amastigotes were only observed inside macrophages in the extradural granuloma and free in the interstitium.…”