path and investigations Flashcards
ELISA for ANA
Indication
- can be screening test for ANA
- usually performed following a positive ANA to detect specific antibodies
- SLE
- > dsDNA
- > anti-smith
- sjogens
- > Ro and La
- scleroderma
- > anti topoisomerase I
- > anti rna polymerase III
procedure
- serum is immobilised in the wells of microtitre plate
- > non-specifically via adsoprtion
- > or specifically via capture by another specific antibody (sandwhich ELISA)
- detection antibody is added
- detection antibody is added
- > forming complex with antigen
- between each step the plate is washed with mild detergent
- > removes proteins/antibodies non specifically bound
- after final wash, enzymatic substrate added
- > produces visible signal indicating quantity of antigen
- signal is detected by spectrophotometry
advantage
- simple to perform
- > can be automated
- > does not require highly trained operators to recognise patterns
disadvantage
- for ANA
- > sensitivity 70-98%
- > specificity 80-98%
- issue with detecting Ro
- poor sensitivity with low titres
FBC
indication
- anaemia
- infection
- coagulopathy
- haemopoetic malignancy
- drugs eg. clozapine
procedure
- barcoded collection tube is inserted into automated analyser
- cell count
- > flow cytometry
- > small amount of blood is aspirated and passed through apeture
- > sensors count and identify the number of cells passing through apeture
- > the size of the cell is determined by the change in impedance as it passes through a current
- > its complexity is determined by passing a laser through its body
- > these results are combined to infer the type of cell
- red cell indices
- > data formed into a bell curve
- > area under curve is red cell count
- > width is RDW
- > mean is MCV
- haemoglobin
- > RBCs are lysed
- > degree colour change of lysate is detected by photometer
advantages
- rapid
- large number of cells = highly precise
disadvantage
- certain abnormal cell may be incorrectly identified
- > eg. haematopoietic progenitor cells
- requires manual review of results
- identification by microscopy
blood grouping
Indication
- assesses the presence or absence of antigens on RBCs and antibodies in the serum
- critical to avoiding
- > acute haemolytic transfusion in a recipient
- > haemolytic disease of the newborn
Procedure
- testing is performed by automated high throughput equipment
- there are 36 different blood group systems
- > the two most common are ABO and Rh
- ABO status is determined by forward and reverse typing
- > agglutination in either test is a positive result
- forward typing is similar to a direct coombs test
- > uses commercially supplied anti-A and anti-B antibodies to detect A or B antigens on RBCs
- reverse typing is similar to an indirect coombs test
- > reagent RBCs are used to detect the reciprocal antibodies in the serum being tested
- Any discrepancies between forward and reverse type are flagged for further investigation
- a similar process occurs to determine presence of Rh antigen on RBCs and anti-D antibody in serum
Possible results
- AB with no antibodies
- > universal RBC recipient
- O (no antigen) with A and B antibodies
- > universal RBC donor
- A with B antibodies
- > donor to A and AB
- > recipient from A and O
- B with A antibodies
- > donor to B and AB
- > recipient from B and O
- reverse relations between blood groups for plasma
- each group is assigned + or - by presence of Rh antigen
- > Rh negative without antibodies can receive + once
- > subsequent transfusions or in patients with prior antibodies would lead to immune transfusion reaction
ESR
Indication
- generally reflects the presence and intensity of inflammatory processes
- > not specific to any disease
- > many causes of raised or low ESR
- > does not distinguish between causes
Procedure
- this lab used the Westergren method
- 2mL of venous blood is anticoagulated
- drawn into a westergren katz tube
- > up to 200mm mark
- placed in rack in strictly vertical position at room temp
- after 1 hour
- > distance from upper limit of RBC sediment to lowest point of surface meniscus is measured
- distance of fall is expressed as mm in 1 hours
- > this is ESR
Factors affecting ESR
- agglutination occurs in two phases
- > formation of rouleaux with no sed
- > formation of spherical agglutinates and sed
- speed of rouleaux formation is therefore major determinant of ESR
- rate of rouleaux determined by
- > opposing zeta potential
- > presence of neutral/negative macromolecules that can bind at anion transport site and cross-bridge
- > these are acute phase reactants of inflammation (fibrinogen) and paraproteins
Results
- increased by
- > inflammation and infection
- > malignancy (particularly MM)
- > trauma
- > anaemia due to reduce impedence between RBCs
- decreased by
- > RBC abnormality eg sickle cell
- > hypofibrinogenaemia eg cirrhosis
- > cachexia
- > heart failure
- normal value between lab, age and sex
- > no normal values for whole population
- > age/2 for men
- > age + 10/2 for women
compared to CRP
- ESR may be elevated when CRP is not
- > eg paraproteins in MM
- ESR also rises and falls much more slowly than CRP
benign renal tumour pathology
It was cut in half along the long axis through the hilum to expose the tumor within.
This was then cut into longitudinal segments to examine the architecture and cells microscopically.
- macroscopic
- 3.5x3.5x3cm mahogany brown lesion in cortex
- well circumscribed
- > not not appear to infiltrate or penetrate capsule
- no central scar, necrosis, haemorrhage or cysts
- uninvolved parenchyma unremarkable
microscopic
- comprised of
- > round cells
- > predominately in solid sheets
- tumour cells
- > abundant granular and eosinophilic cytoplasm
- > round nuclei with centrally placed nucleolus
consistent with renal oncocytoma
oncocytoma background
epidemiology
- rare
- > 3-7% of primary renal neoplasms
- affects twice as many men as women
- usually over age 60
risk factors
- Birt-Hogg-Dubé syndrome
- > rare autosomal syndrome
presentation
- usually asymptomatic
- > detected incidentally on imaging
pathophys
- arises from intercalated cells of collecting duct
- almost always benign
- > has high growth rate
- > generally well encapsulated
- > rarely metastasises
- small risk of metachronous RCC
other types of benign renal tumours
- angiomyolipoma
- chromophobe
renal tumour background
- This was an incidental finding in a 65 year old female
- She presented to her GP with dysphagia
- > hx of HTN otherwise well
- > no constitutional symptoms and no recent weight loss
- suspected of having foreign body lodged in oesophagus
- underwent ultrasound
- > detected a large mass in right superior pole of kidney
- a four phase CT was performed to further characterise the enhancing lesion
- > no renal vein tumour, thrombus or lymphadenopathy
- > reported as Bosniak III
- lab testing revealed renal impairment
- > serum creatinine 160 micromol/dL
- > eGFR of 41
- later underwent radical nephrectomy
clear cell carcinoma pathology
It was cut in half along the long axis through the hilum to expose the tumor within. This was then cut longitudinal segments to examine the architecture and cells microscopically.
macroscopic
- areas of gray-white necrosis and foci of haemorrhage
- yellowy-orange 3.5x3.5x3cm spherical mass in cortex
- > sharply defined
- > confined within capsule
microscopic
- tumour cells
- > rounded
- > abundant clear cytoplasm
- > small nucleoli
- > clustered in nests
- vasculature
- > characteristic chicken wire appearance
- > small and thin walled network
clear cell carcinoma background
epidemiology
-approx 75% of renal cell cancers
risk factors
- PCKD
- smoking
- obesity
- HTN
- VHL disease
pathophys
- thought to arise from proximal convoluted tubules
- in almost all
- > associated with deletions in long arm of chromosome 3
- > deleted region harbours von hipple lindau gene
- in most
- > non deletion mutations of VHL gene
- VHL acts as tumour suppressor gene
- > its loss drives transcription of hypoxia associated genes
- > eg VEGF
clinical presentation
- majority found incidentally on imaging
- local
- > haematuria
- > abdo pain
- > weight loss
- paraneoplastic syndrome
- > CATFACES
treatment
- for stage 1 like this
- > surgery
complications
- local spread
- > renal vein
- > IVC
- haematogenous
- > lung
- > liver
- > bone
- > adrenals
prognosis
- overal
- > 5 year = approx 70%
- early stage
- > 5 year = approx 90%
cholecystitis background and case
A 35-year-old obese woman with a 2-year history of gallstones presented to the emergency department with severe, constant RUQ pain, nausea, and vomiting after eating dinner. She denied any chest pain or diarrhoea.
Three months ago she developed intermittent, sharp RUQ pains.
On physical examination she has a temperature of 38°C, positive murphy’s sign, no peritonism, no jaundice.
Ultrasound demonstrated a distended gall bladder with a positive murphy’s sign, gall stones and a thickened gall bladder wall.
She underwent lapascopic cholecystectomy.
Acute cholecystitis path
General
- 75x30mm gallbladder
- 1cm cystic duct attached
macroscopic
- serosal exudate
- blotchy red exterior
- > hyperaemic due to subserosal haemorrhage
- thickened walls when cut
- contained turbid bile with small stones
- large (approx 1cm) stone in cystic duct
- > round and yellowish
- mucosal was friable
- > no ulceration or penetration
microscopic
- mucosa
- > infiltrated by inflammatory cells (neutrophils)
- wall
- > thickened and oedematous
- > evidence of necrosis
- > fibrin deposition in muscle layer
- no rokitansky aschoff sinuses
appendicitis case
A 22-year-old male presented to the emergency department with abdominal pain, anorexia, nausea, and low-grade fever.
Pain started in the mid-abdominal region 6 hours ago and moved to the right lower quadrant of the abdomen. The pain was steady in nature and aggravated by coughing.
Physical examination reveals a low-grade fever (38°C), pain on palpation at right lower quadrant (McBurney’s sign), some guarding and bowel sounds were present.
Investigations revealed a leukocytosis and ultrasound demonstrated an enlarged, non compressible appendix.
appendix pathology
general
- appendix was 52x10mm long
- attached to mesoappendix
macroscopic
- serosa had dull, granular, erythematous/congested appearance
- > areas of exudate
- mesoappendix appeared much the same
- no evidence of perforation
- internally
- > contained pus and blood
- > small brown faecolith proximally
- > mucosal ulceration
microscopic
- mucosa
- > some necrosis and sloughing
- wall
- > transmural inflammation
- > neutrophils infiltrating
- vessels
- > thrombosed
