SEER is an authoritative source of information on cancer incidence and survival in the United States. SEER currently collects and publishes cancer incidence and survival data from population-based cancer registries covering approximately 28 percent of the U.S. population.
9 - Grade/differentiation unknown, not stated, or not applicable
Malignant mast cell tumor
An exceedingly rare entity characterized by localized but destructive growth of a tumor consisting of highly atypical, immature mast cells. Although initially localized, distant spread is seen after a short interval. The cells may resemble those of Mast cell leukemia (9742/3), and a leukemic phase may occur.
Extremely rare neoplasm characterized by a localized and destructive growth of highly atypical mast cells which can be identified only with the application of appropriate immunohistochemical markers.