Metastatic lung cancer mimicking varicella-zoster virus.

_Case Presentation X Photo Vignette _Letter Authors declare that the contents of this article are their own original unpublished findings. Title: Metastatic lung cancer mimicking varicella-zoster virus Authors: Katherine Snow1 BA, Rylee Moody1 MD, Michael Kremer2 MD, Sofia Chaudhry2 MD Affiliations: 1Saint Louis University, School of Medicine, St. Louis, Missouri, USA, 2SSM Health Saint Louis University Hospital, Department of Dermatology, St. Louis, Missouri, USA Corresponding Author: Katherine Snow, 1008 South Spring Avenue, St. Louis, MO 63110, Tel: 314-617-2660, Email: katherine.snow@health.slu.edu Abstract: Cutaneous metastases from lung adenocarcinoma are rare and usually signify advanced disease with a poor prognosis. This case describes a 63-year-old woman with stage IV lung adenocarcinoma who presented with a painful, initially unilateral, rash on her breast. The clinical appearance of erythematous plaques with vesiculo-papules suggested disseminated herpes zoster, leading to the initiation of intravenous acyclovir. However, histopathology revealed atypical epithelial cells consistent with cutaneous metastasis from the primary lung carcinoma. Although cutaneous metastases from lung cancer typically present as nodules, zosteriform skin metastases are extremely rare. This case is a unique instance of bilateral zosteriform skin metastases from lung carcinoma, underscoring the importance of considering cutaneous metastasis in patients with atypical skin lesions and underlying malignancy. Early recognition and accurate diagnosis are crucial for patient management and prognosis.