gms | German Medical Science

Objective: Collision tumors are defined as two separate lesions which developed simultaneously either in close proximity to each other or even within the same growth. In cases of very heterogeneous lesions they might be misdiagnosed as collision tumors, but the final diagnosis is only made if there was no histological transition between the two histologies. In general those tumor types are very rare. However we report a case of a colliding meningothelial meningioma and chondrosarcoma, which is to our knowledge the first to be reported.

Method: Case report and review of the current literature.

Results: A 42-year-old female was admitted with severe headache and weakness in the right leg. MRI scans revealed a supratentorial contrast enhancing mass at the left posterior parietal lobe originating from the falx, and expanding to the adjacent skull. She underwent a left parietal craniotomy. After resection of exophytic soft bone a yellowish meaty tumor with distinct borders appeared and was totally removed. The weakness of the right leg improved postop, without new neurological deficits. Pathological examination showed different fragments of tissue, including a neoplastic tumor specimen (10x7x3.5cm) composed of bony and cartilaginous parts. Additionally another, yellowish neoplasm (4x2.5x1cm) including dural tissue was found. Microscopic analysis showed the first tumor to be a chondrosarcoma, and the second a meningioma. Immunohistochemical examination revealed increased Ki-67 and vimentin reactivity in both tumors. P53, CD34, Pan-Ck were negative in both tumors. EMA was found to be positive in in the meningioma, whereas S100 was positive exclusively in the chondrosarcoma. Confirmed diagnosis was collision tumor comprised of a low-grade chondrosarcoma (I°) and a meningothelial meningioma (I°).

Conclusions: Simultaneous tumor occurrence of different histologies, esp. in patients without history of phacomatosis or prior radiation, is extremely rare. Since further predisposing factors such as trauma, immune deficiency or oncoviral infections were ruled out, the following proposals on tumor origin and development might be put forward: 1-both tumors originate from the same germinal layer (i.e. ectomesenchymal) 2-The chondrosarcoma developed first with irritant effect on meningoendothelial cells of the dura and 3-patient's pregnancy triggered growth of meningioma component upon progesterone secretion. In conclusion, to our knowledge a collision tumor comprised of meningioma and chondrosarcoma was never reported before.