Leptomeningeal carcinomatosis in sinonasal undifferentiated carcinoma.

BACKGROUND Sinonasal undifferentiated carcinoma (SNUC) is an uncommon neoplasm characterized by local extension and an aggressive course. Treatment often includes a combination of chemotherapy, radiation therapy, and surgery, although the optimal strategy remains unclear. Here, we present the first reported case of leptomeningeal carcinomatosis from SNUC. METHODS AND RESULTS A 28-year-old man with rapidly progressive headaches, congestion, and exophthalmos was found to have a nasal mass. Biopsy revealed sinonasal undifferentiated carcinoma. He had a transient response to chemotherapy followed by a sustained response to concurrent chemoradiation. At the completion of radiation, he developed subtle neurologic findings and MRI revealed diffuse, bulky leptomeningeal spread. He was able to receive only a single fraction of external beam radiation to his spinal axis before his disease rapidly progressed, leading to respiratory failure and death. CONCLUSIONS Sinonasal undifferentiated carcinoma can be associated with leptomeningeal carcinomatosis, which can lead to a fulminant clinical course.