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Hypothetical Patient Management

PRURITUS

Obriz M. Paglinawan
SWU-MHAM-CM Year III Medical Student, 1999

Dr. Reynaldo O. Joson
Facilitator


Trigger 1

Patient with complaint of a "pruritic skin"


Questions:

1. What is a "pruritic skin"?

It is a disagreeable sensation that provokes a desire to scratch. It is a primary sensory impulse carried on unmyelinated C fibers in the spinothalamic tract. It is modulated by central factors, including cortical ones. Not all cases of pruritus are mediated by histamine, though several mediators - bradykinin, neurotensin, secretin, and substance P - release histamine.

The sensation of itch may be elicited by a wide variety of dermatologic disorders and infections or by external stimuli, such as changes in temperature, stroking, or exposure to noxious agents. Itching may also be one manifestation of a systemic disease. Most systemic and cutaneous (delayed-type hypersensitivity) allergic reactions cause pruritus and often present a most challenging diagnostic problem.

2. What are the possible causes of a "pruritic skin"?

GENERALIZED

LOCALIZED

A. Skin Disorders

  • Infections
  • Allergies
  • Chemicals
  • Environmental
  • Trauma

B. Systemic Disorders

  • Cancer
  • Kidney failure
  • Autoimmune diseases
  • Diabetes Mellitus
  • Hypo/Hyperpara-thyroidism
  • Polycythemia vera
  • Liver diseases

C. Psychogenic Disorders

  • Emotional stress
  • Psychotic states

D. Infestations

  • Scabies
  • Pediculosis corporis
  • Hookworm
  • Onchocerciasis
  • Ascariasis

3. What do you think are the more common/least common general and specific condition causing the health problem?

General condition/disorder

Specific condition/disease

Less common

More common

Infestations

Primary Skin disorders

Psychogenic factors

Systemic Disorders


Trigger 2

A 7-year-old child male from Cebu City consulted for the first time due to generalized itchiness on his body.

Physical examination:

Skin: (+) rashes all over the body

Extremities: dry, scaly, hyperpigmented lichenified


Questions:

1. What is your primary and secondary diagnosis?

Primary diagnosis: Contact Dermatitis

Secondary diagnosis: Scabies

2. What are the bases for your primary and secondary diagnoses?

Signs/Symptoms

Contact Dermatitis

Scabies

Rashes

present

present

Pruritus

present

present

3. Do you need more data (sign/symptom) to firm up your primary and secondary diagnoses? YES

If yes, what? How will it firm up your diagnosis?

Additional Data supplied:

History of playing a pet

(+) Hx of Asthma, measles, chicken pox, rhinitis

(+) of self-medication such as Caladryl a few months ago

(+) Hx of going to the beach for family picnic

4. Do you need a paraclinical diagnostic procedure?

If yes, why? YES

If the clinical diagnosis is not so certain and the treatment plan is different and to make certain the primary diagnosis.

If no, why?

If the clinical diagnosis is so certain and the treatment plan is the same.

5. If you need a paraclinical diagnostic procedure, what will you recommend? Why?

Give at least 3 options and then compare using benefit, risk, cost, and availability factors. Then select one demonstrating priority on the primary diagnosis. Shotgun policy is NOT acceptable.

Option

Benefit

Risk

Cost

Availability

CBC

++

++

+

+++

Skin Test

+++

+

+

+++

Burrow ink test

+++

+

+

+++

6. Suppose the patient agreed to your recommendation of the paraclinical diagnostic procedure and suppose it was done.

Skin test was done for its benefit outweighs the risk and the cost for it is specific for atopic dermatitis so that the primary diagnosis will be more certain.


Trigger 3.

A paraclinical diagnostic procedure was done.

Skin test (patch test) was performed.

(+) delayed hypersensitivity (erythema, edema or papulovesicles)


Questions (as applicable):

1. Examine the result of the paraclinical diagnostic procedure and then interpret.

Significance or indications for skin (patch) test:

Can detect suspected allergens

Can determine the presence of:

Significance or indications for burrow ink test:

Can detect mite, ova and feces of the Sarcoptes scabiei

Significance or indications for CBC:

Can detect eosinophilia and increased serum IgE levels as an indication for infection.

2. After the paraclinical diagnostic procedure, what is now your primary and secondary diagnosis? Why?

Primary diagnosis : Atopic Dermatitis

Secondary diagnosis : Scabies

3. Do you need to firm up your diagnosis before you proceed to treatment? If yes, how? NO

The diagnosis is now quite certain because in the patch test that was performed, there was a positive delayed hypersensitivity which was manifested by swollen or reddened skin at the site of the patched skin after a given period of time and their mode of treatment is the same such as by giving topical agents to eradicate the causative agent and the preventive measures of controlling the pruritus.

4. Pretreatment Primary and Secondary Diagnosis:

Primary Diagnosis: Contact Dermatitis

Secondary Diagnosis: Scabies

5. Goals of Treatment

a. Eradication of the clinically evident pruritus.

b. Relief of pain, itchiness and its accompanying signs and symptoms.

c. Patient will survive long.

d. Prevents recurrence of the skin problem.

e. To have a patient who is satisfied, alive, happy and no medical suit.

6. Plan of Management


Trigger 4

The diagnosis of the patient's health problem is CONTACT DERMATITIS


Questions:

1. Advice the patient and relatives on the pathophysiology of the disease. Use diagram.

EXPLANATION

The physiology of itching is not well understood, but it is presumed that various chemomediators (histamine, proteases, prostaglandins) liberated by a wide variety of stimuli and noxious agents (antigen) act on the fine, unmyelinated C nerve fibers near the basal portion of the epidermis to elicit the distinctive sensation of pruritus. Itch as well as pain sensation is transmitted along these small, slow-conducting sensory neurons in the spinal nerves to the spinothalamic tract and then to the thalamus and sensory cortex. It is not clear how scratching relieves itching, but a suggestion is that scratching disturbs the rhythm of afferent impulses travelling toward the spinal cord. Some authorities believe that itching is a subthreshold pain sensation, since itching cannot be elicited in analgetic skin and can be elicited in anesthetized skin (e.g., tabes dorsalis in which pain pathways are preserved). Other investigators regard itching as a distinct sensory modality arising from the outermost nerves of the skin, since removal of the epidermis and subepidermal nerve network abolishes itch (even though cutaneous pain remains) and morphine, while relieving pain, intensifies itching.

Pruritus is the outstanding sensory feature of many skin diseases, and the motor response it evokes, if not controlled leads to further damage of the skin surface, often with perpetuation and intensification of the symptom. This is clearly the case in patients suffering from allergic contact dermatitis, urticaria, and atopic eczema in which itching can be an all-consuming and debilitating symptom. Controlling the itching sensation by way of cold compresses, topical steroids, and oral antihistaminics is frequently crucial in bringing about a resolution of the eczematous response.

2. Advice the patient and relatives on screening of the disease.

The patient must know what causes his pruritus that leads to his skin problem as contact dermatitis. He must know what is contact dermatitis.

Contact dermatitis is an acute or chronic dermatitis that results from direct skin contact with chemicals or allergens. Four-fifths of such disturbance are due to excessive exposure to or additive effects of primary or universal irritants (eg, soaps, detergents, and organic solvents) and are called irritant contact dermatitis. Others are due to actual contact allergy such as poison ivy or poison oak. The most common dermatologic compounds causing allergic rashes include antimicrobials (especially neomycin), topical antihistamines, anesthetics, (benzocaine), hair dyes, preservatives (eg, parabens), latex, and adhesive tape.

Occasional exposure is an important cause of allergic contact dermatitis. Weeping and crusting are typically due to allergic and not irritant dermatitis, which often appears red and scaly. With widespread precautions being taken against HIV infection, contact dermatitis due to latex rubber in gloves and condoms is being seen more frequently.

Therefore, upon knowing these things by the patient, he can better prevent the occurrence and even the recurrence of the skin problem.

3. Advice the patient and relatives on early detection of the disease.

Any rash that is pruritus, the patient must be able to determine and recall of his previous activities whether he was exposed to some allergens, chemicals and etc that leads to the skin problems. Moreover, he must immediately avoid such exposure in order to prevent the occurrence of the skin problems.


REFERENCES

1) Fauci, et. al. Harrison's Principles of Internal Medicine, 14th ed. USA: McGraw-Hill Companies, Inc., vol. 1, 1998, pp. 294-328.

2) Fischbach, Frances Talaska. A Manual of Laboratory Diagnostic Tests, 3rd ed. Philadelphia: J.B. Lippincott Company, 1988.

3) FITZPATRICK TB et al (eds): Dermatology in General Medicine, 4th ed. New York, McGraw-Hill, 1993.

4) Friedman, Harold H. Problem-Oriented Medical Diagnosis, 6th ed. Boston: Little, Brown and Company Inc., 1996.

5) MURPHY GF (ed): Dermatopathology: A Practical Guide to Common Disorders. Philadelphia, Saunders, 1995.

6) Tierney, Lawrence M, et. al. Current Medical Diagnosis & Treatment. Stamford, Connecticut: Appleton & Lange, 1997.

Prepared by:

OBRIZ M. PAGLINAWAN
PBL-III
Obrizpeace@eudoramail.com


Comments from Facilitator


PBL and Distance Learning on Skin and Soft Tissue Problems


SWU-MHAM-CM