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A case of splenic myelolipoma in a German
Shepherd dog.
A.Dernier
1, C. Bayrou
1, D.Desmecht
1, M.Garigliany
1.1. Departemnt of anatomo-pathology, FARAH, Faculty of veterinary Medicine, University of Liege, Belgium
Introduction:
Over the last 20 years, only 15 cases of canine myelolipoma (10 in the spleen, 1 in the adrenal glands, 1 multicentric, 1 occular and 2 in the spinal cord) have been reported. Most of the time, these tumors were asymptomatic. But a case with clinical signs of anemia, vomiting, weight loss, and progressive abdominal distension has been reported. Here, we present the case of an older neutered female German Shepherd dog referred to our Department for necropsic evaluation after euthanasia for chronic renal insufficiency.
Discussion:
The origins of myelolipoma are still a matter of debate. One
hypothesis is that myelolipomas are derived from bone marrow emboli from the adrenal gland. A second theory suggests that myelolipomas are derived from embryonic primitive mesenchymal cells. A third theory
suggests a metaplastic transformation of the site of the myelolipoma. In our case despite severe splenic involvement, the lesion was
asymptomatic. Owever, myelolipoma must be part of the differential diagnosis of multinodular splenic lesions.
Microscopic lesions:
Histology revealed multiple, well-demarcated, unencapsulated masses of hematopoietic elements (1) admixed with mature adipose tissue (2), consistent with a diagnosis of myelolipoma(X200). The capsule of the spleen is visible in the upper part of the field (3).
Macroscopic lesions
:
Necropsic examination revealed multiple off-white splenic nodules. The differential diagnosis included
different splenic tumors such as lymphoma, myeloma, hemangiosarcoma, other sarcoma, mast cells tumor, myelolipoma and histiocytic proliferative disease.
Metastatic neoplastic disease of the spleen is relatively uncommon. Nodular hyperplasia is also part of the
differential diagnosis. An inflammatory phenomen could not be ruled out. To clarify the nature of the lesion,
histologic examination has been undertaken.
Fig 2 : Microscopic observation of one nodule (X40)
Fig. 1: Multifocal coalescing splenic nodules
Fig3 et 4 : In the hematopoïetic element, there is some red cells,
monocyte, lymphocyts, hemosiderophage, megacariocytes (500 X, hematoxylin and eosin)
