Pathergy test:

A 32 year old female patient has presented to the Dermatology OPD for recurrent oral and genital ulcers since last few years.You are suspecting Behcet disease and plan to do a pathergy test.How will you proceed?

PROCEDURE:

VIVA QUESTIONS:

💥What is Pathergy phenomena and pathergy test?

Ans: Pathergy phenomenon is a state of altered tissue reactivity that occurs in response to minor trauma. Pathergy test is an easy to perform skin test to look for the pathergy phenomenon. This test is used as a criteria for Behcet′s disease.

💥Which type of hypersensitivity is pathergy test?

Ans: Type 4 hypersensitivity delayed type cell mediated reaction.

💥What are other sites in which pathergy phenomena occur?

Ans: Any disruption of tissue integrity is potentially associated with an exaggerated inflammatory response in Behcet′s disease.

1.Posttraumatic arterial thrombus and/or aneurysm formation following conventional angiographic interventions
2.superficial thrombophlebitis induced by venipuncture
3.eye inflammation after intra-ocular corticosteroid injections
4.And anastomotic ulcers following surgical treatment of intestinal ulcerated well known examples of pathergy reactions triggered at different tissue sites.

💥What is Pathogenesis of pathergy phenomenon?

Ans: Although the exact mechanisms underlying pathergy phenomenon are unknown, skin injury caused by needle prick apparently triggers a cutaneous inflammatory response which is much more prominent and extensive than that seen in normal skin and suggests an increased or aberrant release of cytokines from keratinocytes or other cells in the epidermis or dermis resulting in a perivascular infiltration observed on skin biopsy.

💥What are Types of pathergy tests? And how to perform and their advantage and disadvantages?

Two types:
Oral pathergy test
Site: lower lip.
Procedure of oral pathergy test : prick the mucous membrane of the lower lip to the submucosa using a 20 gauge blunt disposable needle

Assessment: Readings are taken after 48 h, and the test is considered positive if a pustule or ulcer is seen.

Disadvantage:
Sensitivity: The sensitivity of the oral PT is lower than that of the ordinary skin pathergy test.

Advantage over the skin pathergy test: The oral PT is easier to assess than the skin PT as there is no need to measure the size of the lesion: a pustule or ulcer of any size is considered positive.

Skin pathergy test:
Site: A hairless area on the flexor aspect of the forearms is usually chosen as the test site.

💥What are other routes for pathergy test?

Various routes for skin pathergy testing:
Intradermal (ID)
Intravenous (IV)
and subcutaneous methods have been used.
In a study the positivity rate yielded by intra-dermal needles was statistically higher than that by IV application in Behcet′s patients during both the active and remission periods.

What are Conditions with positive pathergy phenomenon?
Ans:
Behcet′s disease
Pyoderma Gangrenosum
Sweets syndrome
Eosinophilic pustular folliculitis
Inflammatory bowel disease
Healthy individuals

💥What are sites for skin pathergy test?
Ans:

The flexor surfaces of the forearms The lateral aspect of the tibial area
The scapular areas of the back
And the lumbar areas of the abdominal region
A hairless area on the flexor aspect of the forearms is usually chosen as the test site.

Inform the patient that they may feel a sharp prick or a brief sting when the needle is inserted. Also inform about bleeding and bruising (some patients are phobic from the blood and some have to attend an event)
Recommend avoiding the application of any creams, lotions, or other products to the test site ( to prevent allegic contact dermatitis)
Advise the patient to report any signs of infection, excessive redness, swelling, or other unusual symptoms.

U used 5 cc syringe which has 23 guage needle? It should be 20 Guage needle.

Q: What are the limitations of the pathergy test?

A: The pathergy test has a number of limitations, including its lack of specificity for Behcet’s disease, variation in test performance and interpretation, and the influence of external factors such as the technique used and the patient’s geographic origin.The size of the needle, the depth of the needle insertion, and the site of the test can all affect whether a pathergy test result is positive or negative.

Q: WHAT IS PATHERGY PHENOMENON?

The phenomenon of formation of ulcers or non-healing skin lesions following minor injuries is known as PATHERGY  reaction or phenomenon.

Q:What are the indications of pathergy testing?

Although pathergy test is  seen in various diseases,but it is only indicated in Behcet disease for diagnosis as it is included in diagnostic criteria of the disease.

Q:How is cutaneous pathergy test interpreted?

Interpretation is based on visual skin response after 48 hours  of skin prick. Erythema without any induraton surrounding the needle pricks is considered normal thus a negative pathergy test .A papule surrounded by an erythematous halo or the skin can be viewed as a Positive result depending on the size of the papule . 

The papule if transforms into a pustule is considered as Strongly Positive  result.: Positive reactions are scored from 1+  to 4+ depending on the size and presence  of the papules or pustules.

Q:  What is the correlation between strength of cutaneous pathergy test and the disease severity?

No correlation/uncertain 

Q: What are the  factors that can  interfere with the results of the pathergy test?

1-Genetic/Geographic factors(positivity is more in middle east countries and less in US,UK and European countries)

2-Procedure related factors:-

 . 1: Type of needle: Blunt needle increases the possibility and strength of positive pathergy test than sharp needles (disposable)

2- Diameter of the needle: 20 guage needles inflict more skin trauma than needles of  lower guage

3: Sterilization of skin  before performing test lowers the possibility of pathery tests to be positive .(Cause is uncertain)

4: Skin site (more +Ve on forearm than any other site)

5-Difference in pathergy testing protocols.

Q: What is the difference between pathergy and koebnoer phenomenon?

In pathergy phenomenon,skin lesions arising on normal skin due to minor trauma and non specific papule and pustule appear  which may ulcerate even while in koebnoer phenomenon , skin lesions  occuring due to trauma are similar to the underlying disease  clinically and in morphology. On H/P, pathergy lesions show monocytic infiltration while pathergy  lesions show histopathology of underlying disease.

Q: Any new  method of cutaneous pathergy  testing?

Skin prick with self-saliva from patient