Tehran University of Medical Sciences Case Reports in Clinical Practice 2538-2683 8 3 2023 12 02 94 100 Valerio Massimo Magro Echocardiography unit. Department of Internal Medicine and Geriatry, University of Campania “Luigi Vanvitelli”, Piazza L. Miraglia 2, 80100, Naples, Italy Michele Caturano Department of Internal Medicine, AORN San Giovanni di Dio e Ruggi d’Aragona, Salerno, Italy Eugenio Boccalone Department of Internal Medicine and Geriatry, University of Campania “Luigi Vanvitelli”, Naples, Italy Giovanni Scala Geriatrician, doctor responsible for Home Care Center (CAD), RM2 ASL, Rome Walter Verrusio Department of Cardiovascular, Respiratory, Nephrological, Anesthesiological and Geriatric Sciences, Sapienza University of Rome, Rome, Italy 2021 03 20 2021 04 10 Tumors of the chest wall are uncommon lesions that comprise a heterogeneous group of neoplasms. These tumors may arise from osseous structures or soft tissues and may be malignant or benign. We describe the case of a proliferative swelling of uncertain origin that led us to suspect a neuroendocrine origin for the mass we observed and studied. Neuroendocrine tumors arise from neuroendocrine cells, which are peptide- and amine-producing cells dispersed throughout the body. Usually, these tumors occur in various organs as intrathoracic or abdominal masses that become manifest after a variable time, usually after inducing a heterogeneous symptomatology secondary to the secretion of various molecules. The case we describe, on the other hand, develops both exophytically and endophytically, first appearing as an externally developing thoracic mass. Subsequent appropriate investigations revealed bone and muscle involvement in the patient’s thoracic cavity. Therefore, we describe our management of a paucisymptomatic patient who presented with a rapidly developing swelling in the intermammary site that progressed equally rapidly. https://crcp.tums.ac.ir/index.php/crcp/article/view/503