Acute tumor lysis syndrome in a cat with lymphoma

Tumor Lysis Syndrome in Solid Tumors: A Comprehensive Literature Review, New Insights, and Novel Strategies to Improve Outcomes

Tumor lysis syndrome (TLS) is a life-threatening oncological condition that is typically characterized by metabolic derangements that are often labeled as an acute kidney injury. The recent advancement in cancer treatment has led to the mounting rate of TLS in solid tumors that were previously rarely linked to this complication. Given that its prognosis is dismal, it is essential to increase recognition of this condition by describing more sensitive markers. Currently, the management of TLS is mainly supportive due to the lack of specific therapy targeting its specific pathology. This review aims to summarize the most recent literature on the underlying mechanism of TLS and the potential implications for novel TLS therapy.

Review of oncological emergencies in small animal patients

Oncological emergencies can occur at any time during the course of a malignancy and need to be recognized promptly to maximize successful outcomes. Emergencies are characterized as chemotherapy-induced, paraneoplastic syndromes, or directly related to the neoplasm. Prompt identification with treatment of these emergencies can prolong survival and improve quality of life, even in the setting of terminal illness. This review aims to educate the reader on the pathophysiology, clinical presentation and treatment of some of these emergencies, and to review the current veterinary literature to help educate veterinarians in primary and tertiary facilities to know how to diagnose and treat these serious conditions.

Post-chemotherapy perforation in cats with discrete intermediate- or large-cell gastrointestinal lymphoma

Objectives Gastrointestinal (GI) perforation is a well described complication of GI lymphoma in people, commonly occurring within days of initiation of chemotherapy. There are no studies documenting the prevalence of GI perforation in cats with intermediate- or large-cell GI lymphoma or whether it is associated with induction of chemotherapy. The objectives of this study were to document the prevalence and timing of post-chemotherapy perforation in cats with discrete GI masses caused by intermediate- or large-cell lymphoma. Methods Cats with a diagnosis of intermediate- or large-cell lymphoma based on cytologic or histopathologic examination of a mass lesion of the GI tract and treated with chemotherapy were identified by searching the patient record database of three large specialty referral hospitals. Cats undergoing surgical resection of a GI mass prior to chemotherapy were excluded from the study. A clinical diagnosis of GI perforation was made using ultrasound findings and analysis of abdominal fluid. Results Twenty-three cats with intermediate- (n = 3) or large-cell (n = 20) lymphoma were included in the study. GI perforation was confirmed in 4/23 cats (17%), and occurred at 23, 56, 59 and 87 days after induction. There was no association between tumor size, the presence of hypoproteinemia or suppurative inflammation within the mass at the time of diagnosis and subsequent perforation. Post-hoc analysis revealed that the magnitude of weight loss within 15-28 days of diagnosis was greater in cats with perforation. Conclusions and relevance In this pilot study, we found that post-chemotherapy GI perforation in cats with intermediate- or large-cell GI lymphoma occurs. Acute perforation after induction of chemotherapy was not documented. Larger prospective studies are needed to determine risk factors associated with perforation and whether surgical excision would reduce the risk of subsequent GI perforation in these patients.

Hypochloremia in cats - prevalence and associated diseases

OBJECTIVE

To describe the prevalence and possible causes of hypochloremia in the local hospital cat population.

MATERIAL AND METHODS

Retrospective study consisting of two parts. Data were collected from the local electronic medical records database using the search terms "chloride" and "cats" (part A), and "blood gas analysis" and "cats" (part B). The medical records of the hypochloremic cats were then reviewed to determine prior treatment or infusions and to identify major underlying disease processes. Part A included an age and gender matched non-hypochloremic control group, whereas in part B acid-base status was assessed.

RESULTS

Hypochloremia was detected in 367 (27%) of 1363 blood samples. The application of a correction formula to adjust for free water changes decreased the number of hypochloremic cats to 253 (19%). Only a minority had received glucocorticoids or loop diuretics and the prevalence of vomiting was 44%. Common associated disorders were gastrointestinal and respiratory diseases, as well as azotemia and diabetes mellitus. Polyuria/polydipsia, dehydration, prednisolone or furosemide pretreatment, azotemia and diabetes mellitus increased, whereas fluid therapy and the diagnosis of neoplasia decreased the prevalence of hypochloremia. An inverse correlation was found between corrected chloride and standardized base excess (rs = -0.597, p = 0.001) as well as anion gap (rs = -0.4, p = 0.026). 99% of the hypochloremic cats had derangements of acid-base balance.

CONCLUSION

Hypochloremia is a common electrolyte disorder in the local cat population. The correction formula is necessary to adjust for changes in plasma osmolality. Although associated with metabolic alkalosis, most of the hypochloremic cats have a normal or decreased pH. The inverse correlation of chloride and anion gap als well as the high proportion of azotemic or diabetic animals support the concept of compensatory acidosis induced hypochloremia.

CLINICAL RELEVANCE

Hypochloremia should prompt the clinician to performe blood-gas analysis. Diabetes mellitus (especially ketoacidosis) and renal disease should be included in current algorithms for the evaluation of hypochloremic patients.

Hypocalcemia of critical illness in dogs and cats

Hypocalcemia occurs in critically ill dogs and cats and is associated with medications, treatments, and underlying diseases such as acute kidney disease, pancreatitis, parathyroid disease, sepsis, and trauma. Possible underlying mechanisms include hypovitaminosis D, acquired or relative hypoparathyroidism, hypomagnesemia, and alterations in the ionized fraction of calcium caused by changes in chelated or protein-bound calcium. If severe or acute, hypocalcemia can cause obvious clinical signs related to muscle or neurologic hyperexcitability or more subtle signs of cardiovascular dysfunction. Emergency treatment with calcium gluconate administration is recommended when clinical signs are present or if there is moderate to severe ionized hypocalcemia.

Initial evaluation of safety of wide-field irradiation in the treatment of hematopoietic neoplasia in the cat

Localized radiation therapy is well tolerated in cats with confined tumors; however, the use of wide-field radiation therapy to treat disseminated neoplasia has not been evaluated systematically in this species. Wide-field external beam radiation therapy, which we define as irradiation of cranial or caudal halves of the body either individually or sequentially, was undertaken as an experimental option to treat cats with either chemotherapy-refractory or naive hematopoietic neoplasia considered to have a poor prognosis. Fifteen cats with hematopoietic malignancies received wide-field external beam radiation therapy between 2003 and 2006. Cats received 8 Gy delivered in 4 Gy fractions with 60Co photons. Treatment-related toxicity was scored according to criteria established by the Veterinary Cooperative Oncology Group. Animals without preexisting abnormalities on hemograms exhibited no or mild (Grade 1 or 2) hematopoietic toxicity. Although most cats (14 of 15) had preexisting gastrointestinal (GI) signs, these signs were stable (29%) or improved (42%) following irradiation. Worsening GI signs following irradiation occurred transiently in two cats and in association with progressive disease in two others. No pulmonary, renal, hepatic, or dermatologic toxicities were detected. In summary, wide-field external beam radiation therapy can be administered safely to, and may provide therapeutic benefit for, cats with disseminated hematopoietic neoplasia.

Spontaneous acute tumor lysis syndrome as a cause of early deaths in short-term carcinogenicity studies using p53 +/- mice

Acute tumor lysis syndrome (ATLS) is a potentially lethal condition precipitated by the massive release of intracellular components such as nucleic acids, potassium, and phosphorus, following a rapid and widespread lysis of tumor cells. Herein, the authors describe the high incidence and characteristic histopathologic lesions of acute ATLS in p53-deficient mice used in 2 short-term carcinogenicity studies. ATLS was a frequent cause of early death in p53 (+/-) mice in these studies and was consistently associated with the presence of disseminated lymphoma and leukemia. Although a heavy tumor burden and leukemia were present in all affected mice, the absence of ATLS in other mice with equally severe lymphoma and leukemia indicates that these tumor burdens are necessary but insufficient to cause ATLS in mice. The hallmark histopathologic findings of ATLS in mice are the disseminated microemboli composed of nuclear and cytoplasmic debris derived from lysed tumor cells. The mechanical obstruction of capillary beds by these microemboli appeared to be the proximate cause of the early deaths of mice in these studies. Microemboli may contribute to the pathogenesis of acute renal failure and other clinical signs associated with ATLS in other species. Recognition of ATLS in laboratory animals is critical in studies intended to evaluate the efficacy and/or toxicity of anticancer treatments, where early deaths due to ATLS might otherwise be attributed to test article toxicity. Further studies on the role of microemboli in the pathogenesis of ATLS may elucidate pathogenetic mechanisms and lead to improved approaches to clinical management and treatment of this potentially lethal condition.

Case series: acute tumor lysis syndrome in mutator mice with disseminated lymphoblastic lymphoma

Acute tumor lysis syndrome (ATLS) is characterized by severe metabolic abnormalities and organ dysfunction resulting from rapid destruction of neoplastic cells. Metabolic disturbances are thought to be the primary cause of clinical ATLS symptoms, which include renal dysfunction, seizures, and cardiac arrhythmias. The histopathologic lesions associated with organ dysfunction are largely unknown because of the low rate of mortality of ATLS in humans and the few cases of ATLS identified in laboratory animals. Here, we describe histologic, immunohistochemical, and electron microscopic analyses of thirty-one ATLS cases from a cohort of 499 mice that are prone to spontaneous lymphoblastic lymphoma owing to genetic defects in DNA replication fidelity. Seventy-three percent of our cohort died with lymphoblastic lymphoma, and 8% of affected mice died with diffuse microthromboemboli consistent with ATLS. Mice with ATLS had a high spontaneous mortality rate (>50%), a large tumor burden with disseminated disease, and evidence of leukemia. Blood vessels in the lung, kidney, and other organs were occluded by microthromboemboli composed of chromatin, cellular debris, fibrin, platelets, and entrapped erythrocytes and malignant cells. This case series suggests that ATLS can occur at high frequency in mice with disseminated lymphoblastic lymphoma and leads to a high rate of spontaneous death from microthromboemboli.

Diagnostic Exercise

A 22-week-old female 129/SvEv mouse suddenly died in the context of an experiment aimed at defining the efficacy of valproic acid in a mouse model of PML/RARα-induced acute myeloid leukemia. Histologic analysis confirmed the mouse as being affected by a progressive myeloid leukemia, with infiltration of the spleen, bone marrow, liver, kidneys, and lungs. Variably sized intravascular clumps (emboli) of dense basophilic material admixed with necrotic or lytic neoplastic cells were also observed in multiple organs. A positive reaction to Feulgen and Hoechst stain confirmed the high content in chromatin of these basophilic emboli. Cleaved caspase-3 activity was demonstrated both in the leukemic infiltrates and among the intravascular necrotic or lytic neoplastic cells accompanying the basophilic emboli. A diagnosis of acute tumor lysis syndrome related to therapy-induced massive necrosis and/or apoptosis of leukemic cells with subsequent dissemination of emboli of chromatin was proposed.

Pulmonary oedema as a suspected adverse drug reaction following vincristine administration to a cat: A case report

This report describes recurrent respiratory distress following vincristine administration to a cat with chronic lymphocytic leukaemia. The cat was treated with a combination of vincristine, chlorambucil and prednisolone with initial success. After approximately 4 months, dyspnoea developed within 6 h of vincristine administration. Emergency therapy was instituted resulting in a full recovery. Further vincristine was administered; dyspnoea was similarly noted after all but one of these treatments. Dyspnoeic episodes were not attributable to alterations in vincristine dose or method of administration. The repeated temporal association was consistent with a suspected adverse drug reaction to vincristine.

Acute tumour lysis syndrome in a dog with B-Cell multicentric lymphoma

A 5-year-old, spayed female German Shepherd dog was admitted to hospital with marked generalised lymphadenomegaly and splenomegaly. A stage Va B-cell multicentric lymphoma was diagnosed on clinical, cytological (lymph node, bone marrow), histological-immunohistochemical (lymph node excision) and imaging grounds. Since no satisfactory remission was achieved using a multi-drug chemotherapy protocol that included cyclophosphamide, vincristine, cytosine arabinoside, prednisolone, and subsequently supplemented by L-asparaginase, it was replaced by another protocol combining vincristine, L-asparaginase, prednisolone, cyclophosphamide and doxorubicin. Soon after the third weekly session of the second protocol, the clinical status of the animal deteriorated suddenly and severely, with a bleeding tendency, jaundice, hyperuricaemia, hyperphosphataemia, azotaemia, hyperbilirubinaemia and, presumptive disseminated intravascular coagulation. There was also complete regression of lymphadenomegaly. This report emphasises the clinicopathological features and the diagnostic peculiarities of the acute tumour lysis syndrome, which occurs uncommonly in dogs.

Spontaneous acute tumor lysis syndrome in a DBA/1J mouse: a case report and review

Spontaneous acute tumor lysis syndrome (ATLS) was diagnosed in a 10-month-old female DBA/1J sentinel mouse with leukemic lymphoma. The mouse was unable to maintain balance and died shortly after being observed rolling around in its cage. Disseminated neoplastic disease, including a large cranial mediastinal mass, enlarged lymph nodes and splenomegaly, was present at necropsy. Histopathologic examination revealed widespread massive necrosis of lymphoblastic tumor cells, and widely disseminated microemboli composed of nuclear and cytoplasmic cell debris. Although ATLS is widely recognized as an oncologic emergency in humans, acute lesions of ATLS have not been described. The mechanical obstruction of capillary beds by microemboli originating from disintegrating necrotic tumor cells was the likely cause of clinical signs and death in this mouse. We propose that similar microemboli may contribute to the pathogenesis of the acute renal failure and other clinical signs associated with ATLS in humans. Recognition of spontaneous ATLS in laboratory animals is especially important in studies that assess the efficacy and/or toxicity of anticancer treatments, where early deaths due to ATLS might mistakenly be attributed to a direct test article effect.

Artifactually increased serum bicarbonate values in two horses and a calf with severe rhabdomyolysis

Extremely high bicarbonate (HCO3-) and anion gap values were measured in two horses and a calf using the Hitachi 911 automated serum biochemistry analyzer. All three animals had severe muscle disease as evidenced by markedly increased aspartate aminotransferase and creatine kinase activities. Laboratory error was suspected as the source of the increased HCO3- because values calculated from blood gas analysis were normal. It was hypothesized that increased serum lactate dehydrogenase (LDH) activity and pyruvate concentration overwhelmed the oxamate LDH inhibitor in the enzymatic HCO3- assay, resulting in consumption of NADH and falsely elevated spectrophotometric reading. Serum LDH activity was markedly increased in all three patients. In an attempt to reproduce this interference in vitro, LDH and pyruvate were added to normal bovine serum. Bicarbonate concentration was artifactually increased in a linear, dose-response relationship proportional to the amount of LDH activity in the sample; addition of pyruvate augmented this increase. It was concluded that increased serum LDH activity and pyruvate concentration secondary to severe muscle disease can result in artifactual increases in serum HCO3- values obtained by routine enzymatic assay.