Acute Inflammatory Skin
Disorders
Last Updated: September 27, 2022
access_time20 min
Learning Objectives (3)
After completing this brick, you will be able to:
● Describe the typical clinical presentation, pathophysiology, risk
factors, diagnostic features, and treatment of allergic contact
dermatitis.
● 1
● Describe the typical clinical presentation, pathophysiology, risk
factors, diagnostic features, and treatment of urticaria.
● 2
● Describe the typical clinical presentation, pathophysiology, risk
factors, diagnostic features, and treatment of erythema multiforme.
● 3
CASE CONNECTION
When you come home from medical school for the holidays, your 15-
year-old sister says, “Can I talk to you?” and pulls you into the room
away from your parents. “I pierced my belly button a couple of
months ago, and I think it’s infected. Dad will kill me if he finds out.
What should I do?” She lifts her t-shirt to show a red, scaly patch of
skin surrounding her umbilical ring. It doesn’t appear swollen and
isn’t especially tender. There is no drainage from the area. “I don’t
have to take it out, do I?” she asks.
,What will you tell your sister about the red patch around her piercing?
Consider your answer as you read, and we’ll revisit at the end of the
brick.
What Are Acute Inflammatory Skin
Disorders?
Acute inflammatory skin diseases are immune reactions against the
skin that are short-term, lasting for days to weeks; chronic conditions,
in contrast, last longer, sometimes persisting for months to years.
There are many acute inflammatory skin conditions, often triggered
by an allergen. Allergic reactions are an overresponse of the immune
system to common elements in our environment, like foods or plants.
Together, these acute and chronic skin conditions are some of the
most common dermatologic problems that patients experience,
affecting more than 35 million people annually in the United States!
Here we’ll discuss three types of acute inflammatory skin disorders.
The common ones are allergic contact dermatitis and urticaria, but
we’ll also address the less common erythema multiforme.
What Is Allergic Contact Dermatitis?
,Contact dermatitis is an inflammatory skin condition caused by
exposure to an exogenous agent. It is characterized by erythema and
pruritus. Typically, the skin lesions of contact dermatitis are localized
to the site of contact without systemic involvement. Contact
dermatitis is divided into five main categories, which are summarized
in Table 1. In this brick we will focus on allergic contact dermatitis
(ACD).
Contact Dermatitis Description
Irritant Most common subtype. Due to disruption of
epidermal barrier. Irritants can be chemical
(eg, solvents) or physical (eg, wood).
Allergic Delayed hypersensitivity reaction. Due to
exposure to allergens.
Photo-allergic Delayed hypersensitivity reaction. Due to
exposure to UV light.
Systemic allergic Widespread skin involvement in sensitized
patients. Due to systemic allergen exposure
(eg, food ingestion).
Phytophotodermatitis Non-immune. Caused by exposure to
photosensitizing agents released from some
plants (eg, celery).
, Clinical Presentation
As with any contact dermatitis, ACD presents with erythematous,
pruritic rash at the site of contact. The rash configuration can be linear
or geometric. ACD lesions are indurated with distinct borders or
edges. Patients may develop vesicles or bullae. Other than pruritus,
patients may complain of pain or burning sensation at the site of
lesion (Figure 1).
Figure 1
CREDIT: Courtesy of Dr. Richard Usatine
Disorders
Last Updated: September 27, 2022
access_time20 min
Learning Objectives (3)
After completing this brick, you will be able to:
● Describe the typical clinical presentation, pathophysiology, risk
factors, diagnostic features, and treatment of allergic contact
dermatitis.
● 1
● Describe the typical clinical presentation, pathophysiology, risk
factors, diagnostic features, and treatment of urticaria.
● 2
● Describe the typical clinical presentation, pathophysiology, risk
factors, diagnostic features, and treatment of erythema multiforme.
● 3
CASE CONNECTION
When you come home from medical school for the holidays, your 15-
year-old sister says, “Can I talk to you?” and pulls you into the room
away from your parents. “I pierced my belly button a couple of
months ago, and I think it’s infected. Dad will kill me if he finds out.
What should I do?” She lifts her t-shirt to show a red, scaly patch of
skin surrounding her umbilical ring. It doesn’t appear swollen and
isn’t especially tender. There is no drainage from the area. “I don’t
have to take it out, do I?” she asks.
,What will you tell your sister about the red patch around her piercing?
Consider your answer as you read, and we’ll revisit at the end of the
brick.
What Are Acute Inflammatory Skin
Disorders?
Acute inflammatory skin diseases are immune reactions against the
skin that are short-term, lasting for days to weeks; chronic conditions,
in contrast, last longer, sometimes persisting for months to years.
There are many acute inflammatory skin conditions, often triggered
by an allergen. Allergic reactions are an overresponse of the immune
system to common elements in our environment, like foods or plants.
Together, these acute and chronic skin conditions are some of the
most common dermatologic problems that patients experience,
affecting more than 35 million people annually in the United States!
Here we’ll discuss three types of acute inflammatory skin disorders.
The common ones are allergic contact dermatitis and urticaria, but
we’ll also address the less common erythema multiforme.
What Is Allergic Contact Dermatitis?
,Contact dermatitis is an inflammatory skin condition caused by
exposure to an exogenous agent. It is characterized by erythema and
pruritus. Typically, the skin lesions of contact dermatitis are localized
to the site of contact without systemic involvement. Contact
dermatitis is divided into five main categories, which are summarized
in Table 1. In this brick we will focus on allergic contact dermatitis
(ACD).
Contact Dermatitis Description
Irritant Most common subtype. Due to disruption of
epidermal barrier. Irritants can be chemical
(eg, solvents) or physical (eg, wood).
Allergic Delayed hypersensitivity reaction. Due to
exposure to allergens.
Photo-allergic Delayed hypersensitivity reaction. Due to
exposure to UV light.
Systemic allergic Widespread skin involvement in sensitized
patients. Due to systemic allergen exposure
(eg, food ingestion).
Phytophotodermatitis Non-immune. Caused by exposure to
photosensitizing agents released from some
plants (eg, celery).
, Clinical Presentation
As with any contact dermatitis, ACD presents with erythematous,
pruritic rash at the site of contact. The rash configuration can be linear
or geometric. ACD lesions are indurated with distinct borders or
edges. Patients may develop vesicles or bullae. Other than pruritus,
patients may complain of pain or burning sensation at the site of
lesion (Figure 1).
Figure 1
CREDIT: Courtesy of Dr. Richard Usatine
