Factitious Dermatitis Due to Thermal Burn With Histologic Features Simulating Fixed Drug Eruption

Area of Science:

• Dermatology
• Dermatopathology

Background:

• Factitious dermatitis (FD), also known as dermatitis artefacta, is a rare condition characterized by self-inflicted skin lesions.
• Diagnosis can be challenging due to inconsistent patient history and non-specific clinical and histological findings.
• FD can manifest with diverse lesions, including ulcers, erosions, and occasionally bullae resulting from external trauma.

Purpose of the Study:

• To describe a case of bullous FD caused by a thermal burn.
• To identify specific histopathological features that aid in differentiating bullous FD from other dermatoses, particularly fixed drug eruption.

Main Methods:

• Case report of a patient with bullous lesions.
• Detailed histopathological examination of skin biopsy.
• Comparison of findings with known features of factitious dermatitis and fixed drug eruption.

Main Results:

• Histopathology revealed a subepidermal blister, epidermal necrosis, pigment incontinence, and dermal eosinophils and neutrophils.
• Distinct morphologic findings included sharply demarcated necrotic keratinocytes, elongated keratinocytes suggestive of thermal artifact, and multinucleated keratinocytes.
• These features, despite overlap with fixed drug eruption, allowed for the accurate diagnosis of FD.

Conclusions:

• Bullous factitious dermatitis can mimic other inflammatory dermatoses like fixed drug eruption.
• Specific histopathological clues, such as sharp demarcation of necrotic keratinocytes and artifactual changes, are crucial for diagnosing FD.
• While often a diagnosis of exclusion, recognizing these distinct features aids dermatopathologists in accurate diagnosis.