B-cell lymphoblastic lymphoma of the nictitating membrane as the first presenting sign in a 2-year-old Springer Spaniel

Abstract

B-cell lymphoblastic lymphoma is an aggressive malignant disease. Necropsy and microscopical examination revealed widespread disease with a high proliferation index. This is the first reported case of B-cell lymphoblastic lymphoma presenting in the ocular region and only the second reported lymphoma of the nictitating membrane.

Keywords: canine; immunohistochemistry; lymphoblastic; lymphoma; neoplasia; nictitating membrane.

Figure 1

B‐cell lymphoblastic lymphoma of the nictitating membrane. Clinical and histological findings. A, Clinical appearance of the tumor of the nictitating membrane, showing a pinkish tumor measuring 3 × 2.5 × 1.5 cm. The tumor is well vascularized with several new tumor vessels; B, Microscopic overview showing diffuse monotonous infiltration of tumor cells (hematoxylin‐eosin, bar = 50 µm); C, The tumor cells were of medium size and showed pleomorphic features and blast morphology (hematoxylin‐eosin, bar = 50 µm); D, The tumor cells were positive for PAX5 (bar = 50 µm); E, were negative for CD3; however, scattered positive T cells were innocent bystanders (bar = 50 µm); F, Approximately 90% of the cells were positive for Ki‐67, demonstrating a high proliferation index of the tumor cells (bar = 50 µm)

Figure 2

Necropsy observations demonstrating macroscopic and microscopic findings in different organs. A, The spleen was heavily infiltrated by numerous tumors ranging from a few millimeters to 3‐4 cm; B, The microscopic examination of the spleen showed diffuse infiltration of medium‐sized pleomorphic tumor cells. In the specimen, sinusoids (arrow) can be seen (hematoxylin‐eosin, bar = 50 µm); C, A horseshoe‐shaped process of 8 × 6 cm was showing in one liver lobe. The lesion showed central invagination with central necrosis and purulent secretion; D, The liver was diffusely infiltrated with several medium‐sized, pleomorphic tumor cells. Scattered hepatocytes (arrow) can be seen (hematoxylin‐eosin, bar = 50 µm); E, The tonsils of both sides were moderately enlarged (arrows); F, The tonsils were likewise heavily and diffusely infiltrated with tumor cells (hematoxylin‐eosin, bar = 50 µm)