Histopathologic Features of Maculopapular Drug Eruption

Area of Science:

• Dermatology
• Pathology
• Pharmacology

Background:

• Cutaneous adverse drug reactions (CADRs) are prevalent, posing significant healthcare burdens and risks.
• Maculopapular drug eruption (MDE) is the most common CADR but difficult to diagnose clinically and histopathologically due to mimics.
• MDE diagnosis is complicated by varied clinical presentations and histopathologic patterns.

Purpose of the Study:

• To review and summarize the clinical and histopathologic features of MDE.
• To identify characteristic histopathologic findings and their frequencies in MDE.
• To assess the utility of biopsy in diagnosing MDE.

Main Methods:

• Literature review of 327 cases of MDE.
• Analysis of clinical and histopathologic features.
• Summarization of characteristic histopathologic findings and their frequencies.

Main Results:

• Common histopathologic features include epidermal spongiosis, lymphocytic infiltrate, and necrotic keratinocytes.
• Interface changes at the dermal-epidermal junction (DEJ) are noted.
• Superficial perivascular/interstitial lymphocytic infiltrate with potential eosinophils/neutrophils, mild papillary dermal edema, and superficial vessel dilation are observed.
• Multiple histopathologic patterns in a single specimen suggest MDE.

Conclusions:

• Histopathologic criteria, while not fully specific, assist in diagnosing MDE and differentiating it from other conditions.
• Biopsy is a valuable tool for MDE diagnosis by revealing suggestive findings or excluding mimics.
• Clinical-pathologic correlation is essential for accurate MDE diagnosis; biopsy results should not be used in isolation.