What is Unstable Psoriasis
The term "unstable psoriasis" is not a formally defined clinical entity in current dermatology guidelines or literature, but it is commonly used in clinical practice to describe acute, rapidly progressive, or severe variants of psoriasis—particularly pustular and erythrodermic forms—that represent medical emergencies requiring urgent intervention. 1
Clinical Context and Terminology
While the American Academy of Dermatology guidelines do not specifically define "unstable psoriasis" as a diagnostic category, the concept refers to psoriasis that has become acutely severe or is rapidly deteriorating 1. This typically encompasses:
Pustular Psoriasis (Most Severe Variant)
- Pustular psoriasis represents one of the most severe clinical variants, characterized by recurrent episodes of fever followed by new outbreaks of pustules 2
- This form can be life-threatening and requires immediate medical attention 2
Erythrodermic Psoriasis (Generalized Severe Form)
- Erythrodermic psoriasis corresponds to the generalized form where the entire skin becomes bright red and covered by superficial scales 2
- Systemic symptoms include fatigue, myalgia, shortness of breath, fever, and chills 2
- This represents a dermatologic emergency with potential for hemodynamic instability
Triggers That Can Destabilize Psoriasis
Understanding what makes psoriasis "unstable" requires recognizing precipitating factors:
Medication-Induced Destabilization
- Lithium can cause severe, even life-threatening deterioration of psoriasis in patients with pre-existing disease 3
- Antimalarials (chloroquine, hydroxychloroquine) can severely worsen psoriasis 3
- Beta-blockers can exacerbate pre-existing psoriasis, particularly with long-term use 3
- Systemic corticosteroid withdrawal is a well-known trigger for pustular flares (though not explicitly stated in the provided evidence, this is critical clinical knowledge)
Other Destabilizing Factors
- Alcohol can precipitate or worsen psoriasis 3
- NSAIDs can worsen existing disease 3
- Infections, particularly streptococcal infections, can trigger guttate eruptions 2
Clinical Implications for Management
When to Consider Psoriasis "Unstable"
- Rapid progression from plaque to pustular or erythrodermic forms
- Development of systemic symptoms (fever, chills, hemodynamic compromise)
- Acute generalization of previously localized disease
- Failure to respond to standard therapies with worsening clinical picture
Severity Assessment Beyond Body Surface Area
- Psoriasis can be severe irrespective of body surface area when it has serious emotional consequences, occurs in selected locations (hands, feet, scalp, face, genitalia), or causes intractable pruritus 1
- The Psoriasis Area Severity Index (PASI) ranges from 0 to 72 and accounts for body surface area, redness, scaling, and plaque thickness 1
Critical Clinical Pitfall
The most dangerous pitfall is failing to recognize that pustular and erythrodermic psoriasis are medical emergencies requiring hospitalization and aggressive systemic therapy, not simply more severe versions of plaque psoriasis that can be managed outpatient. These patients require monitoring for fluid and electrolyte imbalances, temperature dysregulation, and potential sepsis 2.