Case Study from the year 2025 in the subject Medicine - Anatomy, Physiology, Cytology, , language: English, abstract: This case study details the case of a 50-year-old white Hispanic male from Puerto Padre, Las Tunas, Cuba, who presented with a Left-sided Cervical mass characterized by prominent lymphadenopathy, low-grade fever of short duration, and no significant systemic symptoms or weight loss. Initial diagnostic workup included general hematologic studies, cervical imaging, two Fine Needle Aspiration biopsies of a Submandibular lymph node, and histopathological examination following a left-sided Supraomohyoid functional neck dissection. Both Fine Needle Aspirations were interpreted as positive for Metastatic Carcinoma with Sarcomatous Features. Autoimmune and collagen vascular disorders were considered, and Tuberculosis was excluded. The patient was managed presumptively for Metastatic Lymphadenopathy of Unknown Primary Origin. However, final histopathologic and inmuno histochemical evaluation of the surgical specimen revealed abundant histiocytic infiltration (CD68+), along with reactive T-cell (CD3+) and B-cell (CD20+) populations, consistent with a diagnosis of Necrotizing Histiocytic Lymphadenitis (Kikuchi-Fujimoto Disease). The patient's clinical course was favorable, with complete resolution of symptoms (1-2).