Mielolipoma de adrenal funcional em um cão / Functional adrenal myelolipoma in a dog

ABSTRACT

Background: Myelolipomas are benign tumors composed of a mixture of fat and hematopoietic tissue similar to the bone marrow. They are rare tumors in humans and dogs, and occur generally in the spleen, liver, spinal canal and in the adrenal glands. When they develop in the adrenal glands they feature non-secretory and endocrinologically inactive characteristics, usually without clinical signs or other dysfunctions. Thus, they are often an incidental finding during necropsy. This paper aims to describe a case of functional adrenal gland myelolipoma and spleen myelolipoma in a female dog with clinical signs and laboratory tests compatible with hyperadrenocorticism.Case A 12 year-old female dog, undefined breed, was treated at the Hospital Unit for Companion Animals of the Pontifical Catholic University of Paraná (PUCPR), São José dos Pinhais, Paraná, Brazil, with polyuria, polydipsia, polyphagia, cutaneous hypotonia and central obesity. Blood tests showed hypercholesterolemia and increased alkaline phosphatase; urinalysis identified isostenuria with proteinuria; and ultrasound and MRI of the abdomen indicated right adrenomegaly, with heterogeneous characteristics, without invasion of attached blood vessels and splenic nodules. The low dose dexamethasone suppression test was performed which confirmed hyperadrenocorticism. The animal was submitted to adrenalectomy and splenectomy, and tissue specimens were obtained for histopathological examination, which revealed mature adipocytes and hematopoietic elements in different phases of maturation, compatible with adrenal and spleen myelolipoma. After surgical treatment, there was a progressive improvement of the clinical manifestations and laboratory abnormalities of hypercortisolemia, without recurrence during one year.[...](AU)