Cutaneous adverse reactions resulting from targeted cancer therapies: histopathologic and clinical findings

Targeted cancer treatments—designed to interfere with specific molecular signals responsible for tumor survival and progression—have shown benefit over conventional chemotherapies but may lead to diverse cutaneous adverse effects. This review highlights clinically significant dermatologic toxicities and their associated histopathologic findings, resulting from various targeted cancer drugs. Case reports and series, clinical trials, reviews, and meta-analyses are included for analysis and summarized herein. Cutaneous side effects resulting from targeted cancer therapies were reported with incidences as high as 90% for certain medications, and reactions are often predictable based on mechanism(s) of action of a given drug. Common and important reaction patterns included: acneiform eruptions, neutrophilic dermatoses, hand-foot skin reaction, secondary cutaneous malignancies, and alopecia. Clinical and histopathologic recognition of these toxicities remains impactful for patient care. •Many targeted cancer therapies have been approved in recent years for various indications.•Adverse dermatologist reactions from targeted cancer therapies are common.•Medications which share similar mechanisms of action often demonstrate overlapping adverse reaction profiles.