Concentration of extracellular vesicles isolated from blood relative to the clinical pathological status of dogs with mast cell tumours.

Extracellular vesicles (EVs) are membrane-enclosed fragments shed from all cell types, including tumour cells. EVs contain a wide range of proteins, biolipids and genetic material derived from mother cells and therefore may be potential biomarkers for tumour diagnosis, disease progression and treatment success. We studied the effect of canine mast cell tumours (MCTs) on EV concentrations in blood isolates in association with MCT's histological grade, Ki-67 proliferative index, KIT-staining pattern and number of PLT. The average EV concentration in blood isolates from nine dogs with MCTs was considerably higher than that in blood from eight healthy dogs. But there were no statistically significant differences in EVs concentration in the population of dogs with MCT according to a different histological grade of malignancy (Patnaik, Kiupel), KIT-staining pattern and Ki-67 proliferation index. The results show that these variables statistically do not significantly predicted EV concentrations in blood isolates (P > .05), except the KIT-staining pattern I which added statistically significantly to the prediction (P < .05). The results confirmed the impact of neoplasms on the morphological changes to cell membranes, which result in greater vesiculability and higher EV concentrations.

Mastocytemia associated with a visceral mast cell tumor in a Sumatran tiger (Panthera tigris).

A 6-yr-old male Sumatran tiger (Panthera tigris) with no significant past clinical history was anesthetized for clinical examination after 5 days of lethargy. Clinically, the animal presented with anorexia, pale mucous membranes, and icterus. Hematologic results indicated moderate anemia and severe thrombocytopenia and showed a circulating population of atypical mast cells. The tiger died during anesthesia. On postmortem examination, abdominal hemorrhage associated with marked diffuse hepato-splenomegaly and mesenteric, hepatic, and splenic lymph node hypertrophy were observed. A visceral mast cell tumor was confirmed by histologic examination and toluidine blue staining, with splenic, hepatic, lymphoid, renal, and pulmonary infiltration. Hematologic, postmortem, and histologic findings were consistent with mastocytemia associated with the splenic form of mast cell tumor described in domestic cats.

Significance of mastocytemia in cats.

BACKGROUND: In cats, mastocytemia is considered to be confined to animals with mast cell tumors (MCT), whereas in dogs it is associated with diverse diseases. OBJECTIVE: The objective of this retrospective study was to investigate the diagnostic and prognostic significance of mastocytemia in cats. METHODS: All blood smears and buffy coat (BC) smears on which mast cells were identified over a 6-year period were retrospectively reviewed and mast cells counted. Mastocytemic cats were classified based on their clinical diagnosis. RESULTS: Mastocytemia was identified on 40 blood smears and 13 BC smears from 33 cats. The incidence of mastocytemia detected in cats during routine CBCs was 0.33% (40/12,116 CBCs). Twenty-two of 33 mastocytemic cats (67%) had visceral (n = 17) or cutaneous MCT (n = 7), including 2 that had concurrent visceral and cutaneous involvement. In 3 additional cases (9%), visceral MCT was clinically suspected, but no cytologic or histopathologic evaluation of visceral organs was performed. MCT was excluded in 3 of 33 mastocytemic cats (9%) with a final diagnosis of lymphoid neoplasia (n = 2) and multiorgan hemangiosarcoma (n = 1). Five additional animals (15%) had a diagnosis other than MCT, including lymphoma (n = 2) and chronic renal failure (n = 3), but no cytologic or histopathologic evaluation of the spleen was performed. Blood smears from cats with confirmed MCT had 1-113 mast cells per smear, whereas cats in which MCT was excluded had 1-2 mast cells per smear. CONCLUSIONS: Data confirm that mastocytemia is rare and most commonly found in cats with visceral MCT; however, rare circulating mast cells may also be seen with neoplasms other than MCT.

Evaluation of buffy coat smears for circulating mast cells in healthy cats and ill cats without mast cell tumor-related disease.

OBJECTIVE: To examine buffy coat smears for circulating mast cells in clinically normal cats and cats with illnesses unrelated to mast cell tumors and identify whether conditions other than mast cell tumors are associated with mastocytemia in cats. DESIGN: Prospective study. ANIMALS: 40 clinically normal cats and 40 cats with diseases unrelated to mast cell tumors (all cats were client owned). PROCEDURES: A blood sample for a CBC, serum biochemical analyses, and buffy coat evaluation was obtained from each cat. Ill cats underwent other testing on the basis of their disease process. RESULTS: No mast cells were detected in any sample. Eosinophilia was evident in 11 (27.5%) and 12 (30%) clinically normal and ill cats, respectively. Basophilia was identified in 4 (10%) and 8 (20%) clinically normal and ill cats, respectively. Eight of the 40 (20%) ill cats had neutrophilia. CONCLUSIONS AND CLINICAL RELEVANCE: Circulating mast cells were not identified in clinically normal cats or ill cats without mast cell tumor-related disease. Ill cats did have conditions that caused eosinophilia, basophilia, or neutrophilia. The absence of mast cells in buffy coats obtained from clinically normal and ill cats lends support to the current practice of buffy coat evaluation for tumor staging and follow-up examinations in cats with mast cell tumors. Further studies of buffy coat analysis in cats with different forms of mast cell tumors are indicated to specifically elucidate the test's prognostic value for those patients.

Flushing and increase of serum tryptase after mechanical irritation of a solitary mastocytoma.

Solitary mastocytomas are infiltrates of mast cells in the upper corium, appearing at any side of the body as brownish-reddish plaques in the first months of life. Their course is benign with a spontaneous regression in most cases. A 5-month-old boy presented a 5 x 3 cm sized brownish-yellow plaque on the back of his right hand. His parents reported repeated episodes of swelling and blistering of the skin lesion as well as recurrent systemic flush-reactions. General laboratory parameters were without pathological findings including a normal serum tryptase (5.5 microg/L). A few minutes after rubbing, the lesion became urticarially swollen and the infant developed a general flush reaction accompanied by a bilateral miosis and asthma-like symptoms which disappeared completely after oral administration of 7 drops of dimentinden. Assessment of the serum tryptase two hours after the provocation revealed a more than 5-fold increase (29.3 microg/L) compared to the basic value. We conclude that uncontrolled stroking of mastocytomas should be avoided in patients with a systemic reaction in their history, since this case demonstrates that despite its limited size, mechanical irritation of a solitary mastocytoma may induce strong systemic symptoms as witnessed by transient increase of the serum tryptase, which to our knowledge has not been described in the literature before.