Doxycycline is utilized in pediatric patients 8 years and older for numerous indications, including treatment of acne, Rocky Mountain spotted fever, and Lyme disease. Use of doxycycline in younger patients typically is avoided given the risk for dental enamel hypoplasia, tooth discoloration, and possible delays in skeletal development. Originally utilized for its antibacterial effects as an intracellular inhibitor of protein synthesis, doxycycline has been repurposed for oncologic therapies. It has been shown to have cytotoxic and antiproliferative properties in various cancer cells and also may inhibit leukemic cell migration.26 In PCMZL, doxycycline initially was utilized in Borrelia-positive patients in Europe and found to improve disease clearance.27 In patients without Borrelia infection, doxycycline is thought to enhance apoptosis through caspase-3 activation along with p53 and Bax upregulation.28
Intralesional triamcinolone alone may not be feasible in pediatric PCMZL patients because of widespread involvement, and doxycycline may be considered as a treatment option. Multiple low-risk treatment modalities may be used in conjunction to clear disease in pediatric patients, as demonstrated in our case.
Acknowledgment—We thank Ali Nael Amzajerdi, MD (Orange, California), for his contributions to the pathologic imaging in this report.