The tumor was classified as histiocytic sarcoma.
Histiocytic sarcomas (HS) are rare malignancies of hematopoietic origin, and are thought to derive from mononuclear phagocytic cells or histiocytes. They most commonly involve the intestinal tract, soft tissues of skin, but any organ may be involved. Extensive immunohistochemisty work- up is essential for a correct diagnosis. It should include markers to confirm HS as well as stains to exclude carcinoma, malignancies of mesenchymal origin, other non Hodgkin lymphomas and follicular dendritic cell tumors from the differential diagnosis.
A recent literature review by Wang et al demonstrated only 10 histological proven cases of CNS-HS, of which three occurred in children.5 An extensive search yielded three additional case reports of true CNS-histiocytic sarcomas.1-4 Including our case, only four adult cases of multifocal CNS-HS have been published.1,2,5
Based on these few cases, CNS-HS tumors behave aggressively with very poor prognosis. Known attempted treatments include irradiation, chemotherapy and surgical excision. Only three HS cases showed overall survival of more than 12 months, but these all involved a single localized lesion that could be resected as part of trimodality treatment. Multifocal and hence unresectable disease, like in our patient, was reported in 3 adult cases. Reported survival ranged from 2 months after treatment with whole brain irradiation and chemotherapy to 4 and 10 months after diagnosis despite treatment with steroid- and chemotherapy. Our case confirms this dismal prognosis, and steroid- and chemotherapy (cytaribine) resistance. Of interest, a remarkable radiologic response without clinical improvement was reached after only 6 Gray irradiation. She died three months after diagnosis.
Contributed by M.B.B. Nieuwenhuis MD, S.M.A. van der Salm MD, J.J.C. Verhoeff MD PhD, A.J. van der Kooi MD PhD, I. Slavujecvic-Letic MD, S.T. Pals MD PhD, J.M.I. Vos MD