Original Observation of Primary Bladder Histiocytic Sarcoma: First Case Report.

Histiocytic sarcoma (HS) is a rare malignant lymphohematopoietic neoplasm; it has been cited in the recent World Health Organization (WHO) classification as a malignant proliferation of cells exhibiting morphological and immunophenotypic features of mature histiocytes. To our knowledge, the present case is the first to be described in the bladder of a patient without a history of lymphoma. Only one case has been reported so far regarding a secondary bladder presentation in the setting of a previous diffuse large B-cell lymphoma. We discuss the case of a 68-year-old male who presented with hematuria and dysuria. CT scan revealed a 4-cm intravesical mass that histological examination defined as HS. Our objective was to describe the clinical, histological, immunophenotypical, molecular characteristics and discuss the differential diagnoses of this first case of primary bladder HS. Our research was based on a review of selected articles obtained via the PubMed database. This extremely rare experience provided us with the opportunity to depict an interesting case, highlight its uniqueness, and build up new pathological evidence.