Metastatic uterine histiocytic sarcoma: A rare presentation as solitary paraspinal mass

Histiocytic uterine sarcoma is an extremely rare tumor with aggressive clinical course characterized by the proliferation of histiocytic cells. It is a challenging entity in terms of both diagnosis and therapy. On imaging, it has nonspecific features and a broad range of differentials, depending on regional involvement. Definitive diagnosis often requires a combined approach using microscopic and pathologic analysis in conjunction with an immunohistochemical stains. We present the case of a 65 year old getting diagnosed as a case of endometrial histiocytic sarcoma developing progressive disease over the course of 1 year despite having undergone surgical resection followed by radiation therapy. The pattern of metastatic involvement down the course of her disase is unique in its presentation as a solitary paraspinal mass with no imaging evidence of visceral metastasis. Though uterine sarcomas can metastasize to unusual sites, paraspinal metastasis is almost unprecedented, emphasizing the need for thorough imaging and surveillance. With this report, we not only aim to highlight a rare metastatic presentation of uterine histiocytic sarcoma, but also to give an insight into the clinical features, diagnostic workup, and treatment challenges.