In our diagnostic challenges, we present cases seen by Cornell University’s Clinical Pathology Laboratory. These cover the gamut of venous blood smears, cytologic specimens and result (CBC, chemistry) interpretation, including those pesky erroneous results (usually due to preanalytical errors). A new case will be presented 4-6 times a year. Test yourself with the questions and photomicrographs and make your own diagnosis! The answer along with explanations and discussion is provided on the following page to see how close you came to the diagnosis.
We also have an index of our previous cases (with answers) if you wish to see a list of all the cases. Please note, that the search tool does not search the diagnostic challenges (yet!).
Some of our cases are available as digital slides. So feel free to look at the actual slide used with the case (when available).
A 1-year-old male Great Dane was presented for continued monitoring of a previously diagnosed rare immune-mediated skin disease called Epidermolysis Bullosa Acquisita, which is characterized by the formation of subepidermal blisters.1 The patient was doing well and remission of the immune-mediated disease was maintained with cyclosporine and a tapering dose of methylprednisolone. During the physical examination, the patient was noted to have a firm 2 centimeter dermal mass near the right greater trochanter. A second dermal nodule, measuring about 0.75 centimeters, was noted over the right scapula approximately one month later. There was no reported discomfort noted by the owner for either mass. Cytologic evaluation of a fine-needle aspirate was performed to further investigate the origin of each mass. Stained smears from both masses had similar cytologic findings with representative images shown below.
Given the signalment and location of the masses, what is the expected composition of the clear to light yellow-brown, coarse, elongated to amorphous material in the background?
What differential diagnoses would you have for these cytologic findings?
Figure 1: Mass near greater trochanter (20x objective)
A 13-year-old neutered male Domestic Shorthair was presented to the Cornell University Hospital for Animals for a 2-day history of increased respiratory rate and effort, inappetence, and constipation. The cat was housed indoors and had no known history of trauma. He was diagnosed at a young age with cerebellar hypoplasia and was recently found to be hyperthyroid. On presentation, the cat was weak, had cerebellar ataxia, and was laterally recumbent for the physical examination. Heart sounds were muffled bilaterally and the cat had markedly increased inspiratory effort with abdominal press and tachypnea. He was 5% dehydrated, with diffuse muscle wasting, and a palpable thyroid slip.
Figure 1: Thoracic radiograph
A point-of-care venous blood gas analysis revealed acidemia (pH 7.28 units, reference interval [RI]: 7.32-7.42 units) due to a primary hyperchloremic metabolic acidosis (bicarbonate, 16 mmol/L, RI: 20-25 mmol/L; base excess, -10 mmol/L, RI: -4 to 0 mmol/L; disproportionally high chloride versus sodium concentration) with a compensatory respiratory alkalosis (partial pressure of carbon dioxide, 36 mmHg, RI: 38-46 mmHg). There was a mild hyperkalemia (4.8 mEq/L, RI: 3.8-4.5 mEq/L). A fast ultrasonographic scan of the thorax showed a large cavitated mass in the thoracic cavity with a moderate amount of pleural fluid accumulation. Thoracic radiographs revealed severe, bilateral pleural effusion and a moderate to severe, diffuse interstitial to alveolar pulmonary pattern with reduced lung volume and a large caudal thoracic mass (Figure 1). A medium sized, focal, cranioventral abdominal soft tissue mass was also identified along with bilateral, moderate shoulder osteoarthrosis, which was considered an incidental finding (Figure 1). Quick assessment tests revealed a mild anemia (packed cell volume, 24%, RI: 31-48%) and normal total solid concentration of 6.4 mg/dL (RI, 5.9-7.5 g/dL). A triple snap test for feline leukemia virus, feline immunodeficiency virus and heartworm was negative.
A pleural fluid sample was collected and submitted for cytologic analysis. The fluid was light yellow and opaque with a total protein concentration by refractometer of <2.5 g/dL and a nucleated cell count of 17.5 thou/uL. Examine the representative images of sediment smears of the fluid (Figures 2-4) and answer the questions.
How would you classify the effusion?
Is a cause for the effusion evident?
Figure 2: Pleural fluid from a cat (10x objective)
Figure 3: Pleural fluid from a cat (50x objective)
Figure 4: Pleural fluid from a cat (100x objective)
An 11-year-old female spayed Doberman Pinscher was presented to the Cornell University Hospital for Animals with a 24-hour history of reduced appetite. The dog had also urinated in the bed the previous evening. Six weeks prior, the dog had been admitted to the clinic as an emergency for an acute onset of vomiting and abdominal pain. An exploratory laparotomy was performed, which revealed abdominal adhesions and a gastric perforation. About 2/3 of the stomach was resected and a splenectomy was concurrently performed. The dog had previously tested positive for von Willebrand Disease (vWD; von Willebrand factor antigen concentration: 16%, reference interval, 70-180%) 2 years prior and was given blood transfusions during surgery to assist with surgical hemostasis. Histopathologic evaluation of the resected stomach wall revealed gastritis with Helicobacter organisms and a chronic peritonitis.
On physical examination, the dog had a normal heart and respiratory rate and was not febrile. No abnormalities were detected on abdominal palpation or thoracic auscultation. Blood was taken for a hemogram and biochemical panel. The biochemical profile revealed no relevant abnormalities. Hemogram results are shown below, along with previous results that were taken 2 days after the exploratory laparotomy and 2 years earlier (when vWD testing was done). A hemogram was not done before the emergency surgery. View the hemogram results and representative images of the blood smear (Figures 1-2) then answer the questions below.
What is your diagnosis from the blood smear?
What factors would have predisposed the dog to this condition?
A 14 year old Paint mare was referred to the Cornell Equine Nemo Farm Animal Hospital with a one week history of decreased appetite and a 2-day history of pipestream diarrhea and fever, leading to a preliminary diagnosis of colitis. The day of referral, the referring veterinarian had documented a fever, cold extremities, cyanosis, tachypnea, and tachycardia. Normal gut sounds were auscultated. On arrival at Cornell, physical examination revealed fever, dehydration (prolonged skin tent and capillary refill time > 3 seconds), toxic mucosa, injected sclera, colic associated with passing watery diarrhea, tachypnea and tachycardia. Point-of-care bloodwork revealed a moderate erythrocytosis (59% packed cell volume, reference interval [RI]: 31-48%), severe hyponatremia (118 mEq/L, RI: 134-142 mEq/L), moderate to severe azotemia (5.6 mg/dL creatinine, RI: 0.8-1.5 mg/dL) and lactic acidosis (6.9 mmol/L, normal <2.0 mmol/L). A hemogram performed the next day showed a neutropenia (2.0 x 103/μL, RI: 2.7-6.6 x 103/μL) with a mild to moderate left shift (1.3 x 103/μL, RI: 0-0.1 x 103/μL) and marked toxic change in neutrophils. The fibrinogen concentration by heat precipitation was mildly increased at 400 mg/dL (RI: 0-200 mg/dL). Thoracic auscultation revealed harsh lung sounds. A tracheal wash was collected via an endoscope and submitted for cytologic analysis. Examine the images below then answer the provided questions.
What abnormal findings are present in the tracheal wash?
What is your cytologic diagnosis?
Figure 1: Tracheal wash from a horse (20x objective)
Figure 1: Tracheal wash from a horse (20x objective)
Figure 3: Tracheal wash from a horse (50x objective)
Figure 4: Tracheal wash from a horse (50x objective)
A 1 year old neutered male domestic shorthair cat was presented to a veterinarian for the primary complaints of chronic upper respiratory symptoms, lethargy, and decreased appetite. The cat was documented to be negative for feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) via a rapid test performed at a humane shelter. Upon physical examination, the cat was febrile (104.4°F) and lethargic with bilateral conjunctivitis, prolapsed third eyelids, upper airway congestion and a mucopurulent nasal discharge. The cat was treated with subcutaneous fluids, antibiotics, an antiviral medication (famcyclovir), and an anti-inflammatory medication. The patient showed mild improvement with treatment but symptoms recurred 4 days after the initial examination. A complete blood count (CBC), with an automated white blood cell differential count, performed at the veterinary clinic showed a low normal erythron (hematocrit [HCT], 32%, reference interval [RI], 30-52%) with a marked leukocytosis (218.9 x 103/µL, RI, 2.9-17.0 x 103/µL) characterized by a marked monocytosis (124.6 x 103/µL, RI, 0.1-0.7 x 103/µL) and lymphocytosis (93.6 x 103/µL, RI, 0.9-6.9 x 103/µL). There was a concurrent marked neutropenia (0.5 x 103/µL, RI, 2.3-10.3 x 103/µL) and moderate thrombocytopenia (78 x 103/µL, RI, 151-600 x 103/µL).
The veterinarian submitted an EDTA-anticoagulated blood sample and an unstained blood smear to the Clinical Pathology laboratory in the Animal Health Diagnostic Center at Cornell University for evaluation by a clinical pathologist. On receipt (24 hours after collection), the blood was analyzed with an automated hematology analyzer (Table 1) and a blood smear examination with manual differential count was performed on the submitted blood smear, which was stained with a modified Wright’s stain (Table 1, Figures 1 -3).
What is your diagnosis?
What diagnostic tests can be used to further characterize the cells in blood?
Venous blood from a cat (Wright’s, 20x objective)
Figure 2: Venous blood from a cat (Wright’s, 50x objective)
Figure 3: Venous blood from a cat (Wright’s, 100x objective)
An 11-year-old male alpaca was presented to a veterinarian for a mass in the left axilla. The mass had been discovered one year prior during shearing and was approximately 1 x 2 cm and firm on palpation. The mass had grown substantially in the intervening year and was approximately 6 x 6 x 6 cm when examined by the attending veterinarian. No abnormalities were noted in the overlying skin or hair fibers. The mass was non-painful on palpation and appeared cystic superficially with a firmer deep portion that was well-attached to underlying tissues. Aspirates were taken from the superficial and deep portions of the mass and submitted to the Animal Health Diagnostic Center at Cornell University for cytologic evaluation (Figures 1-4). No digital slide is available for this case.
What cell types can you identify in the aspirate?
What are your differential diagnoses for the mass?
Figure 1: Axillary mass in an alpaca (20x objective)
Figure 2: Axillary mass in an alpaca (20x objective)
Figure 3: Axillary mass in an alpaca (50x objective)
Figure 4: Axillary mass in an alpaca (50x objective)
A 16-year-old Quarter Horse gelding with a history of low thyroid hormone concentrations was being rechecked for possible pituitary pars intermedia dysfunction (PPID). During blood sampling for measurement of adrenocorticotropic hormone (ACTH), insulin, leptin and thyroxine, a large subcutaneous mass was noted in the pectoral region. A fine needle aspirate of the mass was performed and smears of the aspirate were submitted to the Clinical Pathology laboratory in the Animal Health Diagnostic Center at Cornell University for cytologic evaluation. Examine the representative images of the modified Wright’s-stained smears of the aspirate and then answer the questions below.
What cell types can you identify in the aspirate?
What are your differential diagnoses for the mass?
Figure 1: Pectoral mass aspirate in a horse (20x objective)
Figure 2: Pectoral mass aspirate in a horse (50x objective)
Figure 3: Pectoral mass aspirate in a horse (50x objective)
Figure 4: Pectoral mass aspirate in a horse (50x objective)
An 11-year-old female spayed domestic shorthair cat was presented with a 3-4 week history of progressive weight loss. The cat was obtained as a kitten from the island of St John and then had lived on a farm in Massachusetts until 8 years of age. The cat had been solely an indoor cat for the prior 3 years with the current owner.
On examination, the cat was quiet, alert, and responsive, but febrile (102ºF) and tachycardic (200 beats per minute), with slight tachypnea (32 breaths per minute). The rest of the physical examination was within normal limits. Clinical pathology testing revealed normal hemogram results with several abnormalities in a biochemical panel, including hyperglycemia (298 mg/dL, reference interval [RI], 71-182 mg/dL), increased alanine aminotransferase (ALT) (432 U/L, RI, 28-109 U/L), alkaline phosphatase (ALP) (424 U/L, RI, 11-49 U/L), γ-glutamyl transferase (GGT) (10 U/L, RI, 0-2 U/L) activities, and increased total bilirubin concentration (1.6 mg/dL, RI, 0-0.2 mg/dL). Urine dipstick analysis revealed a 2+ reaction for glucose, 3+ reaction for ketones, and 2+ reaction for bilirubin. Abdominal ultrasonography revealed a mildly enlarged liver that was moderately hyperechoic, a full gall bladder with anechoic bile, and a dilated common bile duct. The liver and gall bladder were aspirated and submitted for cytologic evaluation. View the representative photomicrographs of the direct smear of the aspirated bile and answer the questions below.
Based on the provided imaging findings and biochemical results, what disease process(es) is/are occurring in the liver, i.e. what do you expect to see in the liver aspirate?
Can you think of a contributing cause?
What biochemical result is unexpected for the suspected pathologic process involving the liver?
What is your cytologic diagnosis from the bile?
Do the findings in the bile explain the changes in the biochemical panel?
Figure 1: Gall bladder aspirate from a cat (10x objective)
Figure 2: Gall bladder aspirate from a cat (60x objective)
A mature male domestic shorthair cat was presented to Cornell University Hospital for Animals with an ulcerated, non-healing cutaneous and subcutaneous mass over the left mandible close the chin. The left submandibular lymph node was also noted to be moderately enlarged on physical examination. A fine needle aspirate was performed on the mandibular mass and representative figures of a direct smear are shown below. After viewing the images, answer the questions below.
What differential diagnoses should be considered for the left mandibular swelling in this cat?
What is your interpretation based on the cytologic findings?
Figure 1: Mandibular mass aspirate in a cat (20x objective, Wright’s stain)
Figure 2: Mandibular mass aspirate in a cat (50x objective, Wright’s stain)
A 1-year-old spayed female Maltese-cross dog was presented as an emergency to Cornell University Hospital for Animals for acute collapse. The dog had been healthy up until this acute event, which happened suddenly during routine play outdoors. On physical examination, the dog was depressed and hypothermic, tachycardic (250 beats per minute) and tachypneic (78 breaths per minute). Systolic blood pressure was low (96 mmHg systolic/68 mmHg diastolic; reported mean ± standard deviation, 120 ± 19 mmHg systolic and 67 ± 14 mmHg diastolic via oscillometric methods1). The dog was painful on abdominal palpation and had profuse bloody diarrhea. A focused assessment with sonography in trauma (FAST) scan of the abdomen revealed a moderate amount of ascites and edema in the mesentery (hyperechoic), gall bladder wall (thickened wall with hyperechoic and hypo-echoic inner and outer walls, respectively), small intestine (diffusely thick and hyperechoic), and pancreas (thicker than normal with anechoic strands). The sonographic results were compatible with edema in multiple organs.
Results of quick assessment tests showed a packed cell volume (PCV) of 52% (reference interval [RI], 42-54%), total solid concentration of 5 g/dL (RI, 5.9-7.8 g/dL), glucose of 359 mg/dL and urea nitrogen of 15-26 mg/dL. A venous blood gas analysis yielded a pH of 7.43 units (RI, 7.32-7.38 units), with a pCO2 of 28 mmHg (RI, 38-46 mmHg), bicarbonate of 18 mmol/L (RI, 20-25 mmol/L) and base excess of -7 mmol/L (RI, -6 to 0 mmol/L). Sodium and chloride concentrations were 149 (RI, 145-151 mEq/L) and 115 (RI, 110-119 mEq/L) mEq/L, respectively. The pO2 was 45 mmHg (RI, 45-67 mmHg). The lactate concentration was 1.7 mmol/L (normal <2.0 mmol/L; measured 15 minutes after the blood gas analysis).
The dog was treated symptomatically with intravenous fluids, anti-emetics, pain relief and antibiotics overnight and blood was taken for a hemogram, coagulation panel, and biochemical profile the next morning. Results are shown below, along with four questions related to the results.
What is your interpretation of the point-of-care blood gas results?
Considering the quick assessment tests, how would you interpret the changes in analytes in the hemogram and biochemical profile?
What pathologic processes are revealed by the clinical pathologic results?