A talk about the daily operations of a histopathology laboratory - from specimen reception through to tissue embedding.

1. Histopathology in Practice
Sample Reception, Dissection,
Processing, Embedding.
Della Thomas
Senior Biomedical Scientist
Independent Histopathology Services
della.thomas@unilabs.com

2. Histology
The science concerned with the microscopic
structure of tissues and organs in relation to
their function.
Also called microanatomy.

3. Specimen Reception

4. Specimen Unpacking

5. Specimen QC
Mickey Mouse
Rt nasal polyp
DOB:
MOUSE
Mr. MICKEY
18/11/28
26/11/13
Dr. Makewell
Rt nasal polyp
C/O loss of
function - ↓
ability to sniff
out cheese
O/E: nasal polyp
? nature.
18/11/28
123456
Dr. Makewell
26/11/13 8am
M

6. Specimen Labelling

7. Sample documenting
Assign the
specimen to a
pathologist
MOUSE
Mr. MICKEY
Rt nasal polyp
C/O loss of
function - ↓
ability to sniff
out cheese
O/E: nasal polyp
? nature.
18/11/28
123456
Dr. Makewell
26/11/13 8am
M

8. Cassetting

9. Specimen Dissection - the stage

10. Dissecting props
•
•
•
•
•
•
•
•
•
Cutting board
Forceps
Ruler
Scalpel / knives / saw
Inks / dyes
Cassettes / lids
Biopsy pads / tissue
Filter bags
Weighing scales

11. Cut-up dictation
• “Morphology” computer
system
• “Dragon” dictation system
• Hands-free
• Just scan the barcode and
away we go!!

12. Specimen Categories
A
B
C
Specimens only requiring transfer from container
to tissue cassette.
D
E
Dissection and sampling required needing a
moderate level of assessment.
Specimens requiring transfer but with standard
sampling, counting, weighing or slicing.
Simple dissection required with sampling
needing a low level of diagnostic assessment
and/or preparation.
Specimens requiring complex dissection and
sampling methods

13. Category A Specimens
Breast core
biopsies
Endometrium
Colonic series

14. Category B Specimens
Small lipoma
Small skin
biopsy
Cervical LLETZ

15. Category C Specimens
Prepuce
Gallbladder
Haemorrhoids
Appendix

16. Category D Specimens
Pigmented skin
lesions
Large Intestine
(Crohn’s)
C/D
C/D
Skin with markers
Salivary gland
tumour

17. Category E Specimens
Breast cancer
Thyroid (medullary
Ca)
Testis (seminoma)
Uterus (endomet. Ca)

18. Specimen Dissection

19. What does the pathologist
need to know?
Provide good descriptions - say what you see!!
• Shape
• Colour
• Texture
• Dimensions
• Weight
• Distances from margin(s)
• Orientation markers
• Cut surface appearance
etc....
• Keep your fingers crossed for good clinical history

20. Doctors’ handwriting!!
“dysplasia”?
OR “lymphoma”?
Breast Ca....”Steroids”?
OR “Stomach”?
“Nothing” suspicious
OR “Notably” suspicious?

21. Simple transfer
Cervical biopsy
Prostate cores

22. Specimen Sampling
• Literally, taking a sample of the tissue
• Representative
• Generally, fewer blocks required if the tissue
looks uniform throughout (for benign cases)
• Sampling “rules”

23. Sampling rules: prostate chips
• If the chippings weigh 12g
or less, the entire
specimen must be
processed
• If the chippings weigh
more than 12g, a minimum
of 6 cassettes must be
processed
Prostate chips (19g)
Sampled in 8 cassettes:
First 12g = 6 cassettes
• For every 5g over 12g, one
more cassette must be
processed
19g = 7g over 12g
1 cassette per 5g over = 2
more cassettes.

24. Simple dissection
Specimen:
Skin from back
Clinical details:
Sebaceous cyst

25. Simple dissection

26. Unlock the pathology
Fistula-in-ano

27. Unlock the pathology
Gallbladder

28. Unlock the pathology
Cystoprostatectomy
Posterior view

29. Inking
• Resection margins
• Embedding instructions
• Orientation
• Distinguish between samples
• Identify the cut surface
• Acetic Acid

30. Inking resection margins
Pigmented lesion
Cervical cone

31. Embedding Instructions
Ink dots instruct the embedder to embed
the tissue a certain way.

32. Orientation - which way up?
• Anatomical

33. Orientation - which way up?
• Clockface

34. 3 o’clock marker
Clinical Data:
Suture marker
at 3 o’clock.

35. “12 o’clock” marker
Clinical Data:
Tag suture at
12 o’clock.
?

36. “12 o’clock” marker

37. Mapping on a larger scale
Cystoprostatectomy
Prostate
Ureter
Red = Right
Green = Left
Posterior Anterior
bladder bladder

38. Cassette sizes

39. Calcified / firm tissue
Most common:
• Femoral head
• Bone Marrow Trephine
• Ethmoid mucosa / nasal polyps (cartilage)
• Nail
• Hardened cysts

40. Softening
• For bony / hard tissue:
10% Formic Acid
• For nail:
Phenol or hair removal
cream.

41. Firm tissue testing methods
• X-ray - Expensive / ? bench space, but
very accurate
• Chemical end-point test (Ammonium
Hydroxide/Ammonium Oxalate) - very
time consuming, but accurate
• Physical manipulation - not very
accurate, may damage the specimen,
but simple and inexpensive

42. Cutting instructions
•
•
•
•
•
•
•
Levels
Special stains
Unstained Sections
Serial sections
Alopecia protocol
MM sentinel lymph node
Hirschprung’s protocol

43. Specimen Storage
• Ventilated storage units
• Largest buckets lower shelves
• Units are in date (week) order
• 5-weeks’ worth of storage
• Only authorised specimens
are discarded after 5 weeks
• Any outstanding cases are
stored separately until further
notice

44. Processing
Formalin → Alcohol → Xylene → Wax
Wax
Xylene
Formalin
Alcohol

45. Processing programs

46. Embedding
The immortalisation of tissue presentation

47. Embedding Centre
Molten wax
Used lids
Heated chambers
Wax flow adjuster
Hot surface
Cold plates
Wax dispenser

48. Embedding tools

49. Embedding process
Dispense wax
Cool in place
Align tissue
Cassette on

50. Embedding process
ID bead
Top-up wax
Leave to set
Cool plate

51. Embedding tips
• Always keep your eye on the tissue:
even for the most careful embedders,
tissue can ping like tiddlywinks. Make
sure you see where it lands!!
• Ink dots: usually used to instruct the
embedder to embed the tissue a specific
way. Make sure you know your own
lab’s protocol.
• Hide-and-seek: open lids / sponges
carefully - tissue often sticks to them.
~ why it’s important for the embedder to
know number of bits in the cassette
• Cleanliness: always watch out for potential carry-over!!

52. Final block preparation

53. Imagination

54. Thank you
www.slideshare.net/DellaThomas
della.thomas@unilabs.com
www.micro2tele.com
@dellybean (Della Thomas)
@HistoQuarterly (Histology Blog)
www.facebook.com/histoquarterly