Concomitant multiple myeloma and probable phaeochromocytoma in a cat

Cervone, Mario

Three-view thoracic radiographs were unremarkable. Cardiac ultrasonography showed moderate asymmetric hypertrophy with subaortic remodelling and fibrosis, most probably due to increased SAP. Abdominal ultrasonography showed a left adrenal mass ( Figure 2 ), without evidence of vascular invasion. The right adrenal gland was unremarkable. Low-dose dexamethasone suppression (0.1 mg/kg IV) and urine cortisol: creatinine ratio tests were performed to investigate the adrenal activity and a possible inappropriate secretion of hormones by the adrenal mass, but both were within the RIs. Several serum potassium concentrations were repeatedly within the RI and, consequently, excessive aldosterone production was not investigated. Cytological examination of the adrenal mass, obtained by ultrasound-guided fine-needle aspiration (FNA), revealed clusters of intact cells showing polygonal nuclei with prominent nucleoli, pale cytoplasm and fine, basophilic, intracytoplasmic granules (Figure 3a ,b). Furthermore, in order to investigate a potential haematopoietic neoplastic origin of the monoclonal gammopathy, a bone marrow aspirate from the right wing of the ilium was obtained under sedation using a Mallarmé trocar (18 G). Bone marrow cytology indicated an increased myeloid:erythroid ratio due to erythroid hypoplasia, associated with an increase in plasma cells (14%; RI <10%). 1 Plasma cells showed small mature-appearing nuclei and a large cytoplasm filled with one large Golgi apparatus ( Figure 4 ). No malignant changes in the morphology of plasma cells were detected. To investigate a plasmacytic invasion of the spleen and liver, cytological samples were obtained by ultrasound-guided FNA, which revealed no abnormalities. PCR for Leishmania infantum and Mycoplasma species in both blood and bone marrow specimens were negative. Based on these findings, a diagnosis of multiple myeloma (MM), associated with a probable phaeochromocytoma, was made. Previous publications in human medicine have reported a bone marrow plasmacytic invasion induced by cytokines secreted by an adrenal mass, particularly interleukin (IL)-6. 2-4 Measurement of serum IL-6 concentration was not possible and adrenalectomy was declined by the owner. Therefore, immunocytochemistry using feline antibodies to IL-6 (R&D System) was performed on the cytological samples of the adrenal mass. Samples were divided into three different areas and counterstained with a 4',6-diamidino-2-phenylindole solution (ThermoFisher Scientific), according to the manufacturer's instructions. Reaction with feline antibodies to IL-6 was than observed in fluorescence microscopy and was compared with a negative control. Positive reactions of some adrenal cells to IL-6 antibodies were achieved only at a high antibody titre, which is not consistent with IL-6 secretion (Figure 5a,b) .