Pathology mock

Question 1

Scenario: A 60 year old female patient presents at OPD clinic with unilateral firm facial swelling raising the right earlobe. Facial nerve examination is normal.

What is the most likely diagnosis?

Answer 1

-Benign parotid neoplasm

Question 2

What is the most common benign parotid neoplasm?

Answer 2

Pleomorphic adenoma

Question 3

What is the differential diagnosis of unilateral parotid swelling?

Answer 3

Classify:
–> Infection
–> Neoplasm (benign or malignant)
–> Obstruction

Benign neoplasm
-Pleomorphic adenoma
-Warthin’s tumour

Malignant neoplasm
–> adenocarcinoma
–> adenoid cystic carcinoma

Obstruction
–>Sialectasis

Infection:
–> Parotitis
–> Mumps

Question 4

What is the meaning of pleomorphic?

Answer 4

-Variety of histological features reflecting stromal and epithelial tissue elements

Question 5

Describe the histological appearance of a pleomorphic adenoma

Answer 5

-Benign tumour of the parotid gland
-Consists of a mixture of ductal (epithelial) and myoepithelial cells
-Therefore shows both epithelial and mesenchymal differentiation

Question 6

Can pleomorphic adenoma turn malignant? How? What is the most common type of parotid malignancy?

Answer 6

Malignant pleomorphic adenoma is:
–> carcinoma ex pleomorphaic adenoma

Theories on how this develops include:
–> exposure to radiation
–> accumulation of genetic mutations

Most common type is
-Mucoepidermoid carcinoma

Question 7

From your examination, what signs would make you suspect malignant transformation in a parotid swelling?

Answer 7

-Rapidly enlarging mass
-Fixity to underlying tissues
-Ulceration
-Facial nerve palsy
-Presence of lymph nodes

Question 8

In general what are the characteristics of a malignant neoplasm?

Answer 8

-Rapidly enlarging
-Less well differentiated/anaplasia
-Tendency of invasion (local structures and lymphatics/blood vessels)
-Ability to metastasise

Question 9

What simple test in clinic can help differentiate between benign and malignant tumours?

Answer 9

-FNAC

Question 10

What are the cytological features which would raise suspicion of malignancy?

Answer 10

-Loss of normal tissue architecture: normal epithelial cells are arranged in orderly fashion and often have polarity; nucleus is in specific location

-Pleomorphism (variation in nucleus or cell size)

-Hyperchromatic nuclei (increase in nuclear DNA content with subsequent darker H and E staining

-High nucleus to cytoplasmic ratio (due to increase in nucleus size)

-Anaplasia (loss of differentiation)

-Increased rate of mitosis (irregular or bizarre mitosis)

-Giant cells (some malignant cells can coalesce into giant cells)

-Ischaemic necrosis (tumour cells outgrow their blood supply)

Question 11

What is the difference between cytology and histology?

Answer 11

Cytology is the study of individual cells

Histology is the study of tissue architecture, with background parenchyma and connective tissue

Cytology: useful in grading
Histology: useful in staging

Question 12

Interpret the following FNAC findings:
–> langerhans cell + lymphcyte + necrotic material
–> Brown pigmented cells + epithelioid cells
–> Reed sternberg cell + lymphoid cell + blast cell

Answer 12

–> langerhans cell + lymphcyte + necrotic material: granuloma –> TB
–> Brown pigmented cells + epithelioid cells: malignant melanoma
–> Reed sternberg cell + lymphoid cell + blast cell: lymphoma

Question 13

What are the advantages and disadvantages of histology and cytology?

Answer 13

Question 14

Describe the meaning of sensitivity

Answer 14

The percentage of true positives. So a sensitive test has a low percentage of false negatives

The sensitivity of a test is its ability to classify a diseased person as diseased

Question 15

Describe the meaning of specificity

Answer 15

The percentage of true negatives.

Ability of a test to classify non diseased patients as normal

Question 16

How can you differentiate between carcinoma and lymphoma?

Answer 16

By immunohistochemistry

Question 17

What is immunohistochemistry in simple words?

Answer 17

It is a method of localising specific antigens in tissues or cells based on antigen antibody recognition

Question 18

How does immunohistochemistry work?

Answer 18

The antibodies are usually linked to an enzyme or fluorescent dye. When the antibodies bind to the antigen in the tissue sample, the enzyme or dye is activated, and the antigen can then be seen under a microscope

Question 19

What is the type of antigen-antibody reaction in immunohistochemistry?

Answer 19

Complement fixation

Question 20

How can you rule out malignancy intraoperatively?

Answer 20

Can be ruled out with frozen section

Question 21

What is a frozen section?

Answer 21

A pathological laboratory procedure to perform rapid microscopic analysis of a specimen

Question 22

How is the specimen fixed in frozen section?

Answer 22

-Specimen is taken and frozen -20 to 30 degrees
-It is then fixed in gel like medium called OCT
-Subsequently the frozen specimen is cut with a microtome and picked up on a glass slide and stained

Question 23

Needle stick injury: what would you do?

Answer 23

Wound
-Wound is allowed to bleed under running water and washed with soap
-Assess incident risk(e.g. intravascular vs suture needle, depth of injury)
-Assess source patient: take a history for risk factors of blood borne infection.
-Take bloods from patient after consent if indicated
-File incident report and speak to occ health
-Document

Question 24

What are the post operative complications of parotidectomy?

Answer 24

-Facial nerve injury
-Frey’s syndrome
-Fistula
-Great auricular nerve damage

Question 25

What is Frey’s syndrome

Answer 25

-Parasympathetic disruption: fibres which normally supply parotid gland join with sympathetic fibres which supply scalp and face
-Results in gustatory sweating (erythema and sweating instead of salivation)