Dogs with acute myeloid leukemia or lymphoid neoplasms (large cell lymphoma or acute lymphoblastic leukemia) may have indistinguishable mediastinal masses on radiographs

Neurological manifestations in dogs with acute leukemia

Canine acute leukemia is a rare hematopoietic neoplasm. Neurological abnormalities have been frequently reported in dogs with acute leukemia (AL). However, the description of the presentation and findings are limited. This study aimed to describe the clinical findings in dogs with acute leukemia presenting with neurological signs as their primary complaint. The database of a private referral hospital was searched for cases that presented to the neurological department with neurological deficits and were subsequently diagnosed with acute leukemia. Six cases were included; all had neurological clinical signs and an abnormal neurological examination. All cases had a focal neuroanatomical localisation on neurological examination (brain n = 4; spinal = 2). Out of the four dogs with a complete magnetic resonance imaging (MRI) study, there was an ill-defined infiltrative pattern with abnormal signal intensity in the central nervous system (CNS) in three dogs and the loss of grey and white matter differentiation in the brain (n = 2) and/or spinal cord (n = 2). Other MRI findings included abnormal meningeal enhancement (n = 3), changes affecting spinal nerves and epaxial muscles (n = 2), and lymphadenopathy in the field of view (n = 2). The bone marrow assessment on MRI showed evidence of signal change (n = 3), characterized by a loss of normal fat opacity and an abnormal degree of contrast enhancement. The cerebrospinal fluid (CSF) analysis of the four dogs showed an increased protein level with non-specific pleocytosis and without evidence of malignant cells. Treatment with cytotoxic medication was implemented in two dogs. The dogs diagnosed with acute leukemia had focal neuroanatomical localisation, an infiltrative CNS pattern, and bone marrow remodulation on MRI with an increase in CSF protein and negative cytology analysis.

Granulocytic neoplasm suggestive of primary myeloid sarcoma in 3 dogs

Myeloid sarcoma (MS) is a solid tumor of granulocytic origin with extramedullary localization. This tumor is rare in humans and animals. The diagnostic approach is heterogeneous, and the definitive diagnosis may be difficult to achieve. Primary MS has never been described as a spontaneous neoplasm in companion dogs. Two purebred and 1 mixed-breed dogs, 6- to 11-year-old, developed round cell tumors in the mediastinum, lymph nodes (LNs) and tonsils, and LNs, respectively. Granulocytic origin and exclusion of lymphoid lineage were confirmed by flow cytometry, supported by immunohistochemistry or immunocytochemistry. Pivotal to the diagnosis were positive labeling for myeloid (CD11b, CD14) and hematopoietic precursors (CD34) markers, along with negative labeling for lymphoid markers. Blood and bone marrow infiltration were not detected at initial diagnosis, excluding acute myeloid leukemia. The behavior of these tumors was aggressive, resulting in poor clinical outcomes, even when chemotherapy was attempted.

Myeloproliferative Disorder with Intraoral Lesions in an Olive Baboon (Papio anubis)

Spontaneous myeloid leukemia is rarely reported in non-human primates. We report a case of myeloproliferative disorder suggestive of acute myeloid leukemia with intraoral lesions in an olive baboon (Papio anubis). Clinical pathology, radiology, gross examination (pre-mortem and post-mortem), histopathology, and immunohistochemistry findings are provided.