Chemotherapy-induced zosteriform lichen planus following mastectomy: A rare case report.

Introduction: Zosteriform Lichen Planus represents a relatively uncommon variant of LP. It is characterized by a distinctive distribution following Blaschko's line and involving multiple dermatomes, setting it apart as a unique manifestation. There have been several cases of cutaneous LP reported, but relatively few of them presented as zosteriform LP. To our knowledge, this is the first documented case of zosteriform LP as an adverse drug reaction.

Presentation Of Case: A 62-year-old female presented to the dermatology clinic with asymptomatic hyperpigmented patches that exhibited gradual spreading. The patient had a history of breast cancer and underwent a mastectomy procedure, chemotherapy, adjuvant therapy, and radiation treatment. A dermatological examination revealed the presence of multiple hyperpigmented, ill-defined macules arranged linearly on the left flank and inner thigh.

Discussion: A biopsy confirmed the diagnosis as Lichen Planus. The patient's condition significantly improved following a nine-week topical steroid with dose tapering.

Conclusion: Zosteriform LP is a rare adverse skin reaction associated with chemotherapeutic drugs. The immunosuppression induced by chemotherapy may trigger T-cell activation, leading to a lichenoid tissue reaction. A thorough patient history assessment is essential for the management of such adverse reactions.