Elements Of A Medical Case Study


❑ About 30% of occupational skin disorders are allergic contact dermatitis.

❑ In sensitized persons, inflammation begins about 12 hours after exposure to an allergen.

Although contact allergens produce sensitization in only a small percentage of exposed persons, allergic contact dermatitis constitutes about 30% of the skin disorders found in the workplace. Once a person has been sensitized to an offending substance, further exposure may result in relatively rapid development of local inflammation with erythema, papule formation, induration, and weeping vesiculation. Inflammation usually begins about 12 hours after exposure; intensity peaks in 50 hours or more. The rash may spread locally around the margins of the original site or to distant sites that did not have contact with the allergen. Potentially, the entire skin surface could become involved (a condition known as erythroderma or exfoliative dermatitis).


❑ Cross-reactivity with antigenically similar substances can occur with allergic contact dermatitis.

❑ The clinical and histologic appearances of allergic and irritant contact dermatitis are similar.

Allergic contact dermatitis results from a true allergic (i.e., cell-mediated) sensitization to the offending substance. Cross-reactivity with antigenically similar substances may occur. Initially, during the refractory period, the patient may be exposed without developing a reaction. During the induction phase, which may last from 4 days to several weeks (usually about 14 to 21 days), the development of complete allergic sensitization occurs as the allergen comes in contact with the skin. After the skin is fully sensitized, further contact with the allergen may result in rapid and severe dermal manifestations. When no further contact with the allergen occurs, the patient is in the period of persistence of sensitivity. The level of sensitivity can decrease over time, but sensitization may be lifelong.

Most allergens that cause allergic contact dermatitis have molecular weights of less than 500 daltons. The allergens are haptens rather than complete antigens; they must penetrate the skin and combine with endogenous proteins to form full antigens. Langerhans cells play a key role in then presenting the antigen to T lymphocytes, thereby activating the T cells. The sensitized T cells proliferate in the paracortical regions of the lymph nodes and produce effector and memory lymphocytes that remain in the general circulation. On subsequent contact with the complete antigen, the effector cells release lymphokines that may result in rapid and severe, local inflammation.

Many factors can affect the development of allergic contact dermatitis, including characteristics of the allergen itself, patient factors, and environmental conditions. Allergen factors include the physiochemical nature of the allergen (e.g., lipophilicity, solubility, and inherent sensitizing potency), concentration, total dose that comes in contact with the skin, anatomic site of contact, number and frequency of exposures, and occlusion by clothing or gloves.

For Teachers

How to Write a Case Study: The Basics

By Room 241 Team November 22, 2012

The purpose of a case study is to walk the reader through a situation where a problem is presented, background information provided and a description of the solution given, along with how it was derived. A case study can be written to encourage the reader to come up with his or her own solution or to review the solution that was already implemented. The goal of the writer is to give the reader experiences similar to those the writer had as he or she researched the situation presented.

Several steps must be taken before actually writing anything:

  • Choose the situation on which to write
  • Gather as much information as possible about the situation
  • Analyze all of the elements surrounding the situation
  • Determine the final solution implemented
  • Gather information about why the solution worked or did not work

From these steps you will create the content of your case study.

Describe the situation/problem

The reader needs to have a clear understanding of the situation for which a solution is sought. You can explicitly state the problem posed in the study. You can begin by sharing quotes from someone intimate with the situation. Or you can present a question:

  • ABC Hospital has a higher post-surgical infection rate than other health care facilities in the area.
  • The Director of Nursing at ABC Hospital stated that “In spite of following rigid standards, we continue to experience high post-surgical infection rates”
  • Why is it that the post-surgical infection rate at ABC Hospital  higher than any other health center in the area?

This sets the tone for the reader to think of the problem while he or she read the rest of the case study. This also sets the expectation that you will be presenting information the reader can use to further understand the situation.

Give background

Background is the information you discovered that describes why there is a problem. This will consist of facts and figures from authoritative sources. Graphs, charts, tables, photos, videos, audio files, and anything that points to the problem is useful here. Quotes from interviews are also good. You might include anecdotal information as well:

“According to previous employees of this facility, this has been a problem for several years”

What is not included in this section is the author’s opinion:

“I don’t think the infection review procedures are followed very closely”

In this section you give the reader information that they can use to come to their own conclusion. Like writing a mystery, you are giving clues from which the reader can decide how to solve the puzzle. From all of this evidence, how did the problem become a problem? How can the trend be reversed so the problem goes away?

A good case study doesn’t tell the readers what to think. It guides the reader through the thought process used to create the final conclusion. The readers may come to their own conclusion or find fault in the logic being presented. That’s okay because there may be more than one solution to the problem. The readers will have their own perspective and background as they read the case study.

Describe the solution

This section discusses the solution and the thought processes that lead up to it. It guides the reader through the information to the solution that was implemented. This section may contain the author’s opinions and speculations.

Facts will be involved in the decision, but there can be subjective thinking as well:

“Taking into account A, B and C, the committee suggested solution X. In lieu of the current budget situation, the committee felt this was the most prudent approach”

Briefly present the key elements used to derive the solution. Be clear about the goal of the solution. Was it to slow down, reduce or eliminate the problem?

Evaluate the response to the solution

If the case study is for a recent situation, there may not have been enough time to determine the overall effect of the solution:

“New infection standards were adopted in the first quarter and the center hopes to have enough information by the year’s end to judge their effectiveness”

If the solution has been in place for some time, then an opportunity to gather and review facts and impressions exists. A summary of how well the solution is working would be included here.

Telling the whole story

Case study-writing is about telling the story of a problem that has been fixed. The focus is on the evidence for the problem and the approach used to create a solution. The writing style guides the readers through the problem analysis as if they were part of the project. The result is a case study that can be both entertaining and educational.

Tags: Adult Learners, Language Arts


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