Abstract
BACKGROUND: Histiocytic sarcoma (HS) is a rare aggressive malignant neoplasm of hematopoietic cell origin showing features of fever, weight loss, adenopathy, hepatosplenomegaly, and pancytopenia. Primary histiocytic sarcoma of spine without involvement of lymph nodes, bone marrow or systemic features is very rare. Due to highly malignant, aggressive behavior and frequent local and distant metastases, prognosis of histocytic sarcoma is poor. CASE DESCRIPTION: We report a case of primary extranodal variety of histiocytic sarcoma without involvement of bone marrow at extradural location of thoracic spine. Immunohistochemistry panel ruled out other more common lesions in this location. We could not find such presentation of extradural histiocytic sarcoma at the thoracic region in the literature. CONCLUSION: Primary involvement of extradural space by histiocytic sarcoma could arise from the proliferation of multipotent hematopoietic stem cells which are left in this space embroyologically.