	Case 2
Chief Complaint (CC)	A 45-year-old female presents with a complaint of an itchy red rash on her arms and legs for about two weeks.
Subjective	She has been going on a daily basis to the local YMCA with children for Summer camp.
VS	(T) 98.3°F; (RR) 18; (HR) 70, regular; (BP) 118/74
General	healthy-appearing female in no acute distress
HEENT	EYES: no injection, no increase in lacrimation or purulent drainage; EARS: normal TM: Normal
Skin	Mild edema with inflammation located on forearms, upper arms, and chest wall, thighs and knees; primary lesions are a macular papular rash with secondary linear excoriations on forearms and legs.
Neck/Throat	No neck swelling or tenderness with palpation; neck is supple; no JVD; thyroid is not enlarged; trachea midline.

1. What other subjective data would you obtain?

2. What other objective findings would you look for?

3. What diagnostic exams do you want to order?

4. Name 3 differential diagnoses based on this patient presenting symptoms?

5. Give rationales for your each differential diagnosis.

SOLUTION

To further assess the etiology of the rash, ask the patient:

Onset and progression: Did the rash appear suddenly or gradually?
Location and spread: Did it start in one area and spread, or appear all over?
Itching or pain: Is it painful, or primarily itchy?
Associated symptoms: Any fever, chills, fatigue, joint pain, or respiratory symptoms?
Exposure history: Any new soaps, detergents, lotions, or insect bites? Exposure to plants like poison ivy/oak?
Allergy history: Known allergies to medications, foods, or environmental triggers?
Medication history: Any new medications, including OTC drugs or supplements?
Family or contact history: Do others at home or at the camp have similar rashes?
Response to treatment: Has she tried any creams or medications that worsened or improved the rash?

In the physical exam, assess for:

Rash characteristics: Note if it’s raised, flat, vesicular, scaly, or blistering.
Distribution: Is the rash symmetrical or localized to certain areas (e.g., where exposed to irritants)?
Skin integrity: Look for signs of secondary infection like pus, warmth, or oozing.
Lymphadenopathy: Palpate regional lymph nodes to check for inflammation.
Nails and scalp: Check for dermatologic signs that may suggest psoriasis or fungal infection.
Mucous membranes: Look for involvement (which may suggest systemic illness or drug reaction).

Depending on clinical suspicion, consider the following:

Skin scraping with KOH prep: To rule out fungal infection (e.g., tinea corporis).
Patch testing: For allergic contact dermatitis if history supports.
CBC with differential: To assess for eosinophilia or signs of infection.
Skin biopsy: If rash is persistent, atypical, or unresponsive to treatment.
Allergy panel or serum IgE: If allergic reaction is suspected.
Strep test or throat culture: If any pharyngitis or scarlet fever symptoms appear.

1. Allergic Contact Dermatitis

Rationale: The linear excoriations and maculopapular rash localized to exposed areas (arms, legs, chest wall) strongly suggest an allergic reaction to an external irritant, possibly from plants (e.g., poison ivy) or materials encountered at the YMCA (e.g., chlorine, outdoor allergens). Contact dermatitis typically presents after direct skin exposure to allergens.

2. Tinea Corporis (Ringworm)

Rationale: Daily exposure at the YMCA, where children might share towels or mats, increases risk for fungal infections. Tinea corporis often appears as pruritic, circular, red patches that may become scaly and spread. If untreated, excoriations and inflammation may occur due to scratching.

3. Atopic Dermatitis (Eczema)

Rationale: The chronic nature (two weeks), itchy rash, and maculopapular appearance with excoriations fit eczema, especially in predisposed individuals or those with a personal or family history of atopy (e.g., asthma, hay fever). Hot summer weather and increased sweating during camp activities may exacerbate symptoms.

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