Dermal Lymphatic Carcinomatosis as a Cutaneous Metastasis From Epidermal Growth Factor Receptor-Positive Lung Adenocarcinoma: A Case Report

Cutaneous metastases are an uncommon but clinically significant manifestation of internal malignancies. We present a rare case of dermal lymphatic carcinomatosis arising from epidermal growth factor receptor (EGFR)-positive lung adenocarcinoma, a presentation that may closely mimic inflammatory dermatoses and indicate therapeutic resistance or disease progression. We describe the clinical course of a 65-year-old woman who developed a violaceous cutaneous metastatic lesion beneath the left breast during treatment for metastatic lung adenocarcinoma. This case highlights the importance of recognizing cutaneous signs as indicators of disease progression and emphasizes the diagnostic challenges and prognostic implications of cutaneous metastases in lung cancer.